Comparative performance of cryptococcosis diagnostic tests.
Abstract
Cryptococcosis is an important systemic mycosis that threatens the lives of humans and animals. The disease is caused by two species of the genus Cryptococcus: Cryptococcus neoformans and Cryptococcus gattii. The diagnosis of cryptococcosis is made through microscopy, fungal culture followed by biochemical tests, and detection of the cryptococcal capsular antigen (CrAg). Despite the existence of an established diagnostic protocol, the search for new diagnostic tests is necessary due to the high incidence of the disease, with estimates of approximately 1 million cases of cryptococcal meningitis per year and more than 600,000 deaths in patients infected with human immunodeficiency virus (HIV), the potential for C. gattii to cause the disease in immunocompetent individuals, and the disease’s rapid worldwide dissemination. With the development of biotechnology, synthetic peptides have opened up new possibilities as a source of pure epitopes and molecules for the diagnosis of various diseases, based on the detection of circulating antibodies. Synthetic peptides can also be used for the development of vaccines. Studies on Leishmaniasis, Chagas disease, paracoccidioidomycosis, tuberculosis, and, more recently, on cryptococcosis, among others, have shown that this approach shows potential for the early diagnosis of the disease, thus reducing the morbi-lethality of individuals affected by this infection and ultimately changing their prognosis.
Keywords
- Cryptococcosis
- diagnosis
- antigens
- synthetic peptides
- B cell
- epitopes
1. Introduction
Cryptococcosis is an important systemic mycosis that threatens the lives of humans and animals. It manifests primarily through respiratory system diseases and meningoencephalitis. Cryptococcosis is among the emergent fungal infections with significant morbi-lethality, and it is the fourth most frequent cause of opportunistic infection in human immunodeficiency virus (HIV)-positive patients. The disease is caused by two species of the genus
Annually, AIDS-related cryptococcal meningitis is responsible for approximately 15% of the mortality in these individuals [8]. Sub-Saharan Africa has the largest rate of coinfection with
2. Etiological agents
However, this classification becomes difficult, as significant divergences between serotypes are frequently observed at the molecular level [16]. Serotype limits do not entirely coincide with genetic groupings; therefore, serotyping is not regarded as a reliable technique for differentiating strands of
A series of molecular studies were conducted, including polymerase chain reaction (PCR) fingerprinting and amplified fragment length polymorphism (AFLP) analysis of the orotidine monophosphate pyrophosphorylase (
Genotype VGI is endemic in Australia and has also been described in Papua New Guinea, Asia, and southern California. The VGIII and VGIV genotypes are found less frequently, with the VGIII type isolated in the Ibero-American regions and in India and type VGIV recorded in South Africa and in the U.S. [19, 25–29].
3. Natural history of the disease
Cryptococcosis is a systemic mycosis with a pulmonary gateway, which is caused by infection with either
Once in the lung,
4. Virulence factors
The pathogenic species of the genus
The polysaccharide capsule is composed of 90 to 95% glucuronoxylomannan (GXM), 5% galactoxylomannan (GalXM), and approximately 1% mannoproteins (MPs) [40, 41]. It is regarded as one of the most important virulence factors for
5. Diagnosis of cryptococcosis
The laboratory diagnosis of cryptococcosis is based upon a number of principles: the demonstration of the yeast in the clinical material, the isolation of the yeast in the culture followed by biochemical tests for the final identification, anatomic-pathological examination, and research into circulating antigens. Several biological materials may be used for the identification of fungal infection, e.g., serum, plasma, blood, tissue, and CSF, which is the major biological material used for the diagnosis of cryptococcal infection in the CNS [45].
The direct research of the fungus can be accomplished using CSF, sputum, bronchial washing, cutaneous-mucosal lesion pus, urine, macerates of biopsy tissue, prostatic secretion, blood, and bone marrow biopsy specimens. Clinical samples analyzed with India ink indicate the presence of the capsulated yeasts (Figure 1). This method is fast and low-cost but is not very sensitive and cannot distinguish between species. Due to the high yeasts load found in samples from AIDS patients, the sensitivity of this method may reach 80% for cryptococcal meningitis, whereas in immunocompetent individuals, this sensitivity may be as low as 30–72% [46–48]. In addition, the success of this technique is dependent upon the expertise of the microbiologist, and there are reports in the literature of false negatives in 20–30% of the results from infections with

Figure 1.
The culturing of

Figure 2.
After obtaining the isolate, it is necessary to differentiate the species type for clinical and epidemiological purposes [50–52]. Only
The production of urease is a biochemical test used to identify only the genus as both
During infection, the capsular polysaccharides of
The detection of the capsular antigen by agglutination of sensitized particles of latex (LA), which until sometime ago was the immunological method with the most widespread clinical use, may be accomplished in samples from the serum, urine, bronchoalveolar lavage, and CSF. The serological reaction to latex agglutination (LA) is sensitive and specific, emphasizing titers equal to or higher than 1/8 and being able to present cross reaction with the serum of patients with rheumatoid arthritis [62, 64]. The enzyme-linked immunosorbent assay (ELISA) may detect antigens from a cryptococcal infection earlier and at lower titers; however, it is time consuming, expensive, and is laborious. Although CrAg-latex performs as well as EIA and culture, its major limitations are that latex is a manual test and that the resulting interpretation of it is subjective. CrAg-latex and EIA also require laboratory equipment and refrigeration of reagents, making them inadequate for use in environments with minimal infrastructure [61]. The need for refrigeration drastically increases the cost of the test in places with limited resources. Studies report that serological tests with CrAg-latex and EIA may show lower sensitivity when used with strands of some genotypes of
Recently, a new sensitive, low-cost, fast, and non-laborious immunochromatographic assay known as the lateral flow immunoassay (LFA) was made available for purchase for use in serum, CSF, and urine [66]. This method has demonstrated good sensitivity for the detection of cryptococcal antigen (CrAg), primarily in HIV-positive patients [27]. The World Health Organization (WHO) has recommended the use of antigen detection using LFA for patients infected with HIV who show low CD4 cells and are asymptomatic from a neurological viewpoint [67]. This strategy enables the early identification of patients with a cryptococcal disease in the subclinical stage [68]. It has been used in various studies as a form of screening and diagnosis, thus easing its application to clinical practice. Nevertheless, reasonably good results have been accomplished in multiple types of biological specimens, e.g., blood, CSF, and urine [69].
6. Synthetic peptides
The concept of synthetic peptides and protocols for their artificial synthesis was introduced in the early 20th century [70]. Since then, peptides have become increasingly important for biochemistry, medicine, and biotechnology. In 1963, Bruce Merrifield described the development of solid-phase peptide synthesis, a technique that made the large-scale production of synthetic peptides a reality. Since then, various studies with different sizes of synthetic peptides have been reported [71].
In the early 1990s, with the development of biotechnology, recombinant antigens were widely used in clinical diagnosis to detect specific antibodies. However, their use in diagnostic tests presented some problems, such as low immunoreactivity compared with the corresponding purified human antigens, laborious and expensive production, and variation in inter-assay reactivity [72–76].
In this regard, synthetic peptides have opened up a new field and perspective as a source of pure epitopes and molecules for the diagnosis of various infectious and noninfectious diseases based on the detection of circulating antibodies and antigens and can also be used for the development of vaccines [77]. Bioinformatics tools are widely used to predict antigenic and immunogenic regions. These programs are capable of predicting B and T cells epitopes, primarily by building on the known properties of amino acids, e.g., their hydrophilicity, charge, flexibility, exposed surface area, and secondary structure [78–80].
Some factors must be taken into account when dealing with synthetic peptides. The first factor to observe is whether the epitopic area is continuous or discontinuous because the amino acids belonging to the epitope are often separated in the linear sequence and become juxtaposed only when the antigen is in its native conformation. The second factor for observation is the size of the epitope. When this field of study began, researchers worked with only small epitopes as prior to the development of solid-phase peptide synthesis, one could not synthesize very large peptides. The very large peptides (>25–30 amino acids) are more expensive and difficult to produce and also have lower yields. For these reasons, peptides of 10–15 amino acid residues are usually recommended for the production and detection of antibodies [81–83].
The use of synthetic peptides for diagnostic tests confers several advantages, e.g., they are innocuous, easy to store and transport, have a high level of reproducibility with low levels of nonspecific reactions, and retain the possibility of changing the chemistry of the peptide by inserting cysteine residues, fatty acids, or carrier proteins or even by incorporating post-translational modifications, such as phosphorylation [84–86].
Over the past 20 years, several peptide sequences have been used to improve the sensitivity and specificity of tests that use recombinant or native protein as antigens [87–93]. However, the use of synthetic peptides as antigens has grown, with many diagnostic systems that are based on synthetic peptides in production, with some being commercially available at the present time. Some diagnostic tests that use synthetic peptides may already be part of the routine clinical diagnosis of certain diseases that involve viruses, parasites, or autoimmune diseases.
Some of the tests that are already available on the market include tests for Epstein–Barr virus, which examines various epitopes on the capsid protein; hepatitis C virus, which includes synthetic peptides that mimic its structural and nonstructural regions (NS4 and NS5); coronavirus, which is composed of synthetic peptides derived from epitopes of the nucleocapsid and spike proteins and can detect the presence of antibodies from human serum and plasma specimens;
Recent advances have been made in the search for more easily available immunodiagnostic tests for fungal infections. Various methods with high specificity and sensitivity are still under development, with a particular emphasis on the search for markers that are able to detect infections at an early stage. In this regard, Caldini et al. [100] used synthetic peptides from the gp75
With regards to cryptococcosis, the search for new diagnostic tests is necessary due to the high incidence of the disease, with estimates of approximately 1 million cases of cryptococcal meningitis per year and more than 600,000 deaths in HIV-infected patients, the potential for
As previously mentioned, diagnostic methods based upon the detection of antibodies have been developed and successfully applied to various other infectious diseases. The efficacy of these methods is not impacted by the antigenic charge of the microorganism, which is particularly relevant for the diagnosis of cryptococcosis, whose major diagnostic tests, LA and LFA, are dependent on the charge of the antigen.
The early diagnosis of cryptococcosis is a challenge that science and the health system must face as in most cases, the disease is diagnosed late, which results in significant morbidity and mortality. Thus, efforts should be made toward finding a rapid, sensitive, and specific diagnosis. In this sense, the identification of multiple immunogenic targets and the possibility of synthesizing these artificial targets appear to be a promising alternative for the development of more accurate tests for the diagnosis of systemic mycosis.
In this area, Martins et al. [104] have adopted an innovative strategy that combines the technology of proteomics and bioinformatics, with the aim of identifying multiple immunogenic targets for a diagnostic test for cryptococcosis. Linear B-cell epitopes of immunoreactive proteins for
In the search for a faster and more specific test, Brandão et al. [105] tested various synthetic peptides derived from immunoreactive proteins of
|
|
|
|
India ink | 30–80 | 100 | [46–48] |
Culture | 80 | 100 | [106] |
CrAg-LA | 93–100 | 93–98 | [62] |
CrAg-EIA | 93–100 | 93–98 | [62] |
CrAg-LFA | 99–100 | 92–100 | [106] |
Synthetic peptides | 55–79 | 90–100 | [105] |
Table 1.
CrAg, cryptococcal antigen; EIA, enzyme immunoassay; LFA, lateral flow assay; LA, latex agglutination
Hsp70 is a conserved protein that has been increasingly studied worldwide for its role in various biological processes, including the interaction of
Higher diagnostic performance can be achieved with multi-epitope chimeric proteins. This type of antigen becomes more attractive because it has more than one antigen-binding site, thus multiplying the possibilities for increasing antigenicity. Brandão et al. demonstrated in a theoretical model (
The use of this technology for the development of a diagnostic test capable of the early identification of cryptococcosis and the possibility of building an effective vaccine for this disease are essential for significant reduction in the morbidity and mortality of individuals affected by this infection and may ultimately change their prognosis.
References
- 1.
Del Poeta M, Casadevall A. Ten challenges on Cryptococcus and Cryptococcosis. Mycopathologia. 2012;173(5):303–310. DOI: 10.1007/s11046-011-9473-z - 2.
Springer DJ, Chaturvedi V. Projecting global occurrence of Cryptococcus gattii. Emerg Infect Dis. 2010;16(1):14–20. DOI: 10.3201/eid1601.090369 - 3.
Byrnes EJ 3rd, Li W, Lewit Y, Ma H, Voelz K, Ren P, Carter DA, Chaturvedi V, Bildfell RJ, May RC, Heitman J. Emergence and pathogenicity of highly virulent Cryptococcus gattii genotypes in the northwest United States. PLoS Pathog. 2010;4(1):e1000850. DOI: 10.1371/journal.ppat.1000850 - 4.
D'Souza CA, Kronstad JW, Taylor G, Warren R, Yuen M, Hu G, Jung WH, Sham A, Kidd SE, Tangen K, Lee N, Zeilmaker T, Sawkins J, McVicker G, Shah S, Gnerre S, Griggs A, Zeng Q, Bartlett K, Li W, Wang X, Heitman J, Stajich JE, Fraser JA, Meyer W, Carter D, Schein J, Krzywinski M, Kwon-Chung KJ, Varma A, Wang J, Brunham R, Fyfe M, Ouellette BF, Siddiqui A, Marra M, Jones S, Holt R, Birren BW, Galagan JE, Cuomo CA. Genome variation in Cryptococcus gattii, an emerging pathogen of immunocompetent hosts. MBio. 2011;2(1):e00342-10. DOI: 10.1128/mBio.00342-10 - 5.
Kidd SE, Hagen F, Tscharke RL, Huynh M, Bartlett KH, Fyfe M, Macdougall L, Boekhout T, Kwon-Chung KJ, Meyer W. A rare genotype of Cryptococcus gattii caused the cryptococcosis outbreak on Vancouver Island (British Columbia, Canada). Proc Natl Acad Sci U S A. 2004;101(49):17258-17263. - 6.
Center of Disease Control and Prevention. Emergence of Cryptococcus gattii – Pacific Northwest, 2004–2010. Am J Transplant. 2011;11(9):1989–1992. DOI: 10.1111/j.1600-6143.2011.03749.x - 7.
Chen SCA, Meyer W, Sorrell TC. Cryptococcus gattii infections. Clin Microbiol Rev. 2014;27(4):980–1024. DOI: 10.1128/CMR.00126-13 - 8.
Park BJ, Wannemuehler KA, Marston BJ, Govender N, Pappas PG, Chiller TM. Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDS. AIDS. 2009;23(4):525–530. DOI: 10.1097/QAD.0b013e328322ffac - 9.
Jarvis JN, Lawn SD, Wood R, Harrison TS. Cryptococcal antigen screening for patients initiating antiretroviral therapy: Time for action. Clin Infect Dis. 2010;51(12):1463–1465. DOI: 10.1086/657405 - 10.
Rajasingham R, Rhein J, Klammer K, Musubire A, Nabeta H, Akampurira A, Mossel EC, Williams DA, Boxrud DJ, Crabtree MB, Miller BR, Rolfes MA, Tengsupakul S, Andama AO, Meya DB, Boulware DR. Epidemiology of meningitis in an HIV-infected Ugandan cohort. Am J Trop Med Hyg. 2015;92(2):274–279. DOI: 10.4269/ajtmh.14-0452 - 11.
Vidal JE, Boulware DR. Lateral flow assay for Cryptococcal antigen: An important advance to improve the continuum of HIV care and reduce Cryptococcal meningitis-related mortality. Rev Inst Med Trop Sao Paulo. 2015;57(Suppl 19):38–45. DOI: 10.1590/S0036-46652015000700008 - 12.
Kwon-Chung KJ, Bennett JE. Cryptococcosis. In: Kwon-Chung KJ, Bennett JE, editors. Medical Mycology. Philadelphia: Lea & Febiger; 1992. p. 397–446. - 13.
Kwon-Chung KJ, Boekhout T, Wickes BL, Fell JW. Systematics of the genus Cryptococcus and its type species C. neoformans. In: Heitman J, Kozel TR, Kwon-Chung KJ, Perfect JR, Casadevall A, editors. Cryptococcus: From human pathogen to model yeast. Washington: ASM Press; 2011. p. 3–15. - 14.
Bovers M, Hagen F, Boekhout T. Diversity of the Cryptococcus neoformans-Cryptococcus gattii species complex. Rev Iberoam Micol. 2008;25(1):S4–12. - 15.
Kwon-Chung KJ, Boekhout T, Fell JW, Diaz M. Proposal to conserve the name Cryptococcus gattii against C. hondurianus. Taxon. 2002;51:804–806. - 16.
Abegg MA, Cella FL, Faganello J, Valente P, Schrank A, Vainstein MH. Cryptococcus neoformans and Cryptococcus gattii isolated from the excreta of psittaciformes in a southern Brazilian zoological garden. Mycopathologia. 2006;161(2):83–91. - 17.
Boekhout T, Theelen B, Diaz M, Fell JW, Hop WC, Abeln EC, Dromer F, Meyer W. Hybrid genotypes in the pathogenic yeast Cryptococcus neoformans. Microbiology. 2001;147(Pt 4):891–907. - 18.
Litvintseva AP, Kestenbaum L, Vilgalys R, Mitchell TG. Comparative analysis of environmental and clinical populations of Cryptococcus neoformans. J Clin Microbiol. 2005;43(2):556–564. DOI: 10.1128/JCM.43.2.556-564.2005 - 19.
Meyer W, Castañeda A, Jackson S, Huynh M, Castañeda E; IberoAmerican Cryptococcal Study Group. Molecular typing of IberoAmerican Cryptococcus neoformans isolates. Emerg Infect Dis. 2003;9(2):189–195. DOI: 10.3201/eid0902.020246 - 20.
Ngamskulrungroj P, Gilgado F, Faganello J, Litvintseva AP, Leal AL, Tsui KM, Mitchell TG, Vainstein MH, Meyer W. Genetic diversity of the Cryptococcus species complex suggests that Cryptococcus gattii deserves to have varieties. PLoS One. 2009;4(6):e5862. DOI: 0.1371/journal.pone.0005862 - 21.
MacDougall L, Kidd SE, Galanis E, Mak S, Leslie MJ, Cieslak PR, Kronstad JW, Morshed MG, Bartlett KH. Spread of Cryptococcus gattii in British Columbia, Canada, and detection in the Pacific Northwest, USA. Emerg Infect Dis. 2007;13(1):42–50. DOI: 10.3201/eid1301.060827 - 22.
Datta K, Bartlett KH, Baer R, Byrnes E, Galanis E, Heitman J, Hoang L, Leslie MJ, MacDougall L, Magill SS, Morshed MG, Marr KA; Cryptococcus gattii Working Group of the Pacific Northwest. Spread of Cryptococcus gattii into Pacific Northwest region of the United States. Emerg Infect Dis. 2009;15(8):1185–1191. DOI: 10.3201/eid1508.081384 - 23.
Trilles L, Lazéra M, Wanke B, Theelen B, Boekhout T. Genetic characterization of environmental isolates of the Cryptococcus neoformans species complex from Brazil. Med Mycol. 2003;41(5):383–390. DOI: 10.1080/1369378031000137206 - 24.
Trilles L, Lazéra Mdos S, Wanke B, Oliveira RV, Barbosa GG, Nishikawa MM, Morales BP, Meyer W. Regional pattern of the molecular types of Cryptococcus neoformans and Cryptococcus gattii in Brazil. Mem Inst Oswaldo Cruz. 2008;103(5):455–462. DOI: 10.1590/S0074-02762008000500008 - 25.
Chen S, Sorrell T, Nimmo G, Speed B, Currie B, Ellis D, Marriott D, Pfeiffer T, Parr D, Byth K. Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand. Clin Infect Dis. 2000;31(2):499–508. DOI: 10.1086/313992 - 26.
Ellis D, Marriott D, Hajjeh RA, Warnock D, Meyer W, Barton R. Epidemiology: Surveillance of fungal infections. Med Mycol. 2000;38(Suppl 1):173–182. - 27.
Harris J, Lockhart S, Chiller T. Cryptococcus gattii: Where do we go from here?. Med Mycol. 2012;50(2):113–129. DOI: 10.3109/13693786.2011.607854 - 28.
Choi YH, Ngamskulrungroj P, Varma A, Sionov E, Hwang SM, Carriconde F, Meyer W, Litvintseva AP, Lee WG, Shin JH, Kim EC, Lee KW, Choi TY, Lee YS, Kwon-Chung KJ. Prevalence of the VNIc genotype of Cryptococcus neoformans in non-HIV-associated cryptococcosis in the Republic of Korea. FEMS Yeast Res. 2010;10(6):769–778. DOI: 10.1111/j.1567-1364.2010.00648.x - 29.
Viviani MA, Cogliati M, Esposto MC, Lemmer K, Tintelnot K, Colom Valiente MF, Swinne D, Velegraki A, Velho R; European Confederation of Medical Mycology (ECMM) Cryptococcosis Working Group. Molecular analysis of 311 Cryptococcus neoformans isolates from a 30-month ECMM survey of cryptococcosis in Europe. FEMS Yeast Res. 2006;6(4):614–619. DOI: 10.1111/j.1567-1364.2006.00081.x - 30.
Li SS, Mody CH. Cryptococcus. Proc Am Thorac Soc. 2010;7(3):186–196. DOI: 10.1513/pats.200907-063AL - 31.
Jongwutiwes U, Sungkanuparph S, Kiertiburanakul S. Comparison of clinical features and survival between cryptococcosis in human immunodeficiency virus (HIV)-positive and HIV-negative patients. Jpn J Infect Dis. 2008;61(2):111–115. - 32.
Moretti ML, Resende MR, Lazéra MS, Colombo AL, Shikanai-Yasuda MA. Guidelines in cryptococcosis – 2008. Rev Soc Bras Med Trop. 2008;41(5):524–544. - 33.
Cohen J, Perfect JR, Durack DT. Cryptococcosis and the basidiospore. Lancet. 1982;319(8284):1301. DOI: 10.1016/S0140-6736(82)92861-6 - 34.
Lin X, Heitman J. The biology of the Cryptococcus neoformans species complex. Annu Rev Microbiol. 2006;60:69–105. DOI: 10.1146/annurev.micro.60.080805.142102 - 35.
Littman ML, Schneierson SS. Cryptococcus neoformans in pigeon excreta in New York City. Am J Hyg. 1959;69(1):49–59. - 36.
Krockenberger MB, Malik R, Ngamskulrungroj P, Trilles L, Escandon P, Dowd S, Allen C, Himmelreich U, Canfield PJ, Sorrell TC, Meyer W. Pathogenesis of pulmonary Cryptococcus gattii infection: A rat model. Mycopathologia. 2010;170(5):315–330. DOI: 10.1007/s11046-010-9328-z. Epub 2010 Jun 15 - 37.
Weatherhead SC, Charlton FG, Reynolds NJ. Plaques, papules, and nodules in a 40-Year-Old Man. Arch Dermatol. 2006;142(7):921–926. DOI: doi:10.1001/archderm.142.7.921-a - 38.
Kronstad JW, Attarian R, Cadieux B, Choi J, D'Souza CA, Griffiths EJ, Geddes JM, Hu G, Jung WH, Kretschmer M, Saikia S, Wang J. Expanding fungal pathogenesis: Cryptococcus breaks out of the opportunistic box. Nat Rev Microbiol. 2011;9(3):193–203. DOI: 10.1038/nrmicro2522 - 39.
Kwon-Chung KJ, Fraser JA, Doering TL, Wang Z, Janbon G, Idnurm A, Bahn YS. Cryptococcus neoformans and Cryptococcus gattii, the etiologic agents of cryptococcosis. Cold Spring Harb Perspect Med. 2014;4(7):a019760. DOI: 10.1101/cshperspect.a019760 - 40.
McFadden DC, De Jesus M, Casadevall A. The physical properties of the capsular polysaccharides from Cryptococcus neoformans suggest features for capsule construction. J Biol Chem. 2006;281(4):1868–1875. DOI: 10.1074/jbc.M509465200 - 41.
Rakesh V, Schweitzer AD, Zaragoza O, Bryan R, Wong K, Datta A, Casadevall A, Dadachova E. Finite-element model of interaction between fungal polysaccharide and monoclonal antibody in the capsule of Cryptococcus neoformans. J Phys Chem B. 2008;112(29):8514–8522. DOI: 10.1021/jp8018205 - 42.
Bose I, Reese AJ, Ory JJ, Janbon G, Doering TL. A yeast under cover: The capsule of Cryptococcus neoformans. Eukaryot Cell. 2003;2(4):655–663. DOI: 10.1128/EC.2.4.655-663.2003 - 43.
Collins HL, Bancroft GJ. Encapsulation of Cryptococcus neoformans impairs antigen-specific T-cell responses. Infect Immun. 1991;59(11):3883–3888. - 44.
Monari C, Paganelli F, Bistoni F, Kozel TR, Vecchiarelli A. Capsular polysaccharide induction of apoptosis by intrinsic and extrinsic mechanisms. Cell Microbiol. 2008;10(10):2129–2137. DOI: 10.1111/j.1462-5822.2008.01196.x - 45.
Beyene T, Woldeamanuel Y, Asrat D, Ayana G, Boulware DR. Comparison of cryptococcal antigenemia between antiretroviral naïve and antiretroviral experienced HIV positive patients at two hospitals in Ethiopia. PLoS One. 2013;8(10):e75585. DOI: 10.1371/journal.pone.0075585 - 46.
Saha DC, Xess I, Jain N. Evaluation of conventional & serological methods for rapid diagnosis of cryptococcosis. Indian J Med Res. 2008;127(5):483–488. - 47.
Snow RM, Dismukes WE. Cryptococcal meningitis: Diagnostic value of cryptococcal antigen in cerebrospinal fluid. Arch Intern Med. 1975;135(9):1155–1157. - 48.
Imwidthaya P, Poungvarin N. Cryptococcosis in AIDS. Postgrad Med J. 2000;76:85–88. - 49.
Namiq AL, Tollefson T, Fan F. Cryptococcal parotitis presenting as a cystic parotid mass: Report of a case diagnosed by fine-needle aspiration cytology. Diagn Cytopathol. 2005;33(1):36–38. - 50.
Fries BC, Goldman DL, Cherniak R, Ju R, Casadevall A. Phenotypic switching in Cryptococcus neoformans results in changes in cellular morphology and glucuronoxylomannan structure. Infect Immun. 1999;67(11):6076–6083. - 51.
Fries BC, Taborda CP, Serfass E, Casadevall A. Phenotypic switching of Cryptococcus neoformans occurs in vivo and influences the outcome of infection. J Clin Invest. 2001;108(11):1639–1648. - 52.
Lacaz CS, Porto E, Martins JEC, Heins-Vaccari EM. Criptococose. In: Lacaz CS, Porto E, Martins JEC, Heins-Vaccari EM, Melo NT, editors. Tratado de micologia, 1st ed. São Paulo: Sarvier; 2002. p. 416–440. - 53.
Canelo C, Navarro A, Guevara M, Urcia F, Zurita S, Casquero J. Determinación de la variedad de cepas de Cryptococcus neoformasn aisladas de pacientes con SIDA. Rev Med Exp. 1999;15(1–2):44–47. - 54.
Kwon-Chung KJ, Polacheck I, Popkin TJ. Melanin-lacking mutants of Cryptococcus neoformans and their virulence for mice. J Bacteriol. 1982;150(3):1414–1421. - 55.
Khan ZU, Al-Anezi AA, Chandy R, Xu J. Disseminated cryptococcosis in an AIDS patient caused by a canavanine-resistant strain of Cryptococcus neoformans var. grubii. J Med Microbiol. 2003;52(Pt 3):271–275. DOI: 10.1099/jmm.0.05097-0 - 56.
Nakamura Y, Kano R, Sato H, Watanabe S, Takahashi H, Hasegawa A. Isolates of Cryptococcus neoformans serotype A and D developed on canavanine-glycine-bromthymol blue medium. Mycoses. 1998;41(1–2):35–40. DOI: 10.1111/j.1439-0507.1998.tb00373.x - 57.
Cox GM, Mukherjee J, Cole GT, Casadevall A, Perfect JR. Urease as a virulence factor in experimental cryptococcosis. Infect Immun. 2000;68(2):443–448. DOI: 10.1128/IAI.68.2.443-448.2000 - 58.
Casali AK, Goulart L, Rosa e Silva LK, Ribeiro AM, Amaral AA, Alves SH, Schrank A, Meyer W, Vainstein MH. Molecular typing of clinical and environmental Cryptococcus neoformans isolates in the Brazilian state Rio Grande do Sul. FEMS Yeast Res. 2003;3(4):405–415. DOI: 10.1016/S1567-1356(03)00038-2 - 59.
Denning DW, Stevens DA, Hamilton JR. Comparison of Guizotia abyssinica seed extract (birdseed) agar with conventional media for selective identification of Cryptococcus neoformans in patients with acquired immunodeficiency syndrome. J Clin Microbiol. 1990;28(11):2565–2567. - 60.
Jacobson ES. Pathogenic roles for fungal melanins. Clin Microbiol Rev. 2000;13(4):708–717. - 61.
Makadzange AT, McHugh G. New approaches to the diagnosis and treatment of cryptococcal meningitis. Semin Neurol. 2014;34(1):47–60. DOI: 10.1055/s-0034-1372342 - 62.
Perfect JR, Bicanic T. Cryptococcosis diagnosis and treatment: What do we know now. Fungal Genet Biol. 2015;78:49–54. DOI: 10.1016/j.fgb.2014.10.003 - 63.
Boulware DR, Rolfes MA, Rajasingham R, von Hohenberg M, Qin Z, Taseera K, Schutz C, Kwizera R, Butler EK, Meintjes G, Muzoora C, Bischof JC, Meya DB. Multisite validation of cryptococcal antigen lateral flow assay and quantification by laser thermal contrast. Emerg Infect Dis. 2014;20(1):45–53. DOI: 10.3201/eid2001.130906 - 64.
Mitchell TG, Perfect JR. Crytococcosis in the era of AIDS – 100 years after the discovery of Cryptococcus neoformans. Clin Microbiol Rev. 1995;8(4):515–548. - 65.
Antinori S. New insights into HIV/AIDS-associated cryptococcosis. ISRN AIDS. 2013:471363. DOI: 10.1155/2013/471363 - 66.
Lindsley MD, Mekha N, Baggett HC, Surinthong Y, Autthateinchai R, Sawatwong P, Harris JR, Park BJ, Chiller T, Balajee SA, Poonwan N. Evaluation of a newly developed lateral flow immunoassay for the diagnosis of cryptococcosis. Clin Infect Dis. 2011;53(4):321–325. DOI: 10.1093/cid/cir379 - 67.
Rajasingham R, Meya DB, Boulware DR. Integrating cryptococcal antigen screening and pre-emptive treatment into routine HIV care. J Acquir Immune Defic Syndr. 2012;59(5):e85–91. DOI: 10.1097/QAI.0b013e31824c837e - 68.
World Health Organization. Rapid Advice: Diagnosis, Prevention and Management of Cryptococcal Disease in HIV-Infected Adults, Adolescents and Children. Geneva: World Health Organization; 2011. 44. DOI: 13: 978-92-4-150297-9 - 69.
Rugemalila J, Maro VP, Kapanda G, Ndaro AJ, Jarvis JN. Cryptococcal antigen prevalence in HIV-infected Tanzanians: A cross-sectional study and evaluation of a point-of-care lateral flow assay. Trop Med Int Health. 2013;18(9):1075–1079. DOI: 10.1111/tmi.12157. - 70.
Wieland T, Bodanszky M. The World of Peptides: A Brief History of Peptide Chemistry. 1st ed. Berlin: Springer-Verlag; 1991. 298. DOI: 10.1007/978-3-642-75850-8 - 71.
Merrifield RB. Solid phase peptide synthesis. I. The synthesis of a tetrapeptide. J Am Chem Soc. 1963;85(14):2149–2154. DOI: 10.1021/ja00897a025 - 72.
Gonzalez L, Boyle RW, Zhang M, Castillo J, Whittier S, Della-Latta P, Clarke LM, George JR, Fang X, Wang JG, Hosein B, Wang CY. Synthetic-peptide-based enzyme-linked immunosorbent assay for screening human serum or plasma for antibodies to human immunodeficiency virus type 1 and type 2. Clin Diagn Lab Immunol. 1997;4(5):598–603. - 73.
Leinikki P, Lehtinen M, Hyöty H, Parkkonen P, Kantanen ML, Hakulinen J. Synthetic peptides as diagnostic tools in virology. Adv Virus Res. 1993;42:149–186. - 74.
Routsias JG, Tzioufas AG, Moutsopoulos HM. The clinical value of intracellular autoantigens B-cell epitopes in systemic rheumatic diseases. Clin Chim Acta. 2004;340(1–2):1–25. DOI: 10.1016/j.cccn.2003.10.011 - 75.
Thorpe R, Wadhwa M, Mire-Sluis A. The use of bioassays for the characterisation and control of biological therapeutic products produced by biotechnology. Dev Biol Stand. 1997;91:79–88. - 76.
Yan SC, Grinnell BW, Wold F. Post-translational modifications of proteins: Some problems left to solve. Trends Biochem Sci. 1989;14(7):264–268. DOI: 10.1016/0968-0004(89)90060-1 - 77.
Noya O, Patarroyo ME, Guzmán F, Alarcón de Noya B. Immunodiagnosis of parasitic diseases with synthetic peptides. Curr Protein Pept Sci. 2003;4(4):299–308. DOI: 10.2174/1389203033487153 - 78.
Sun P, Ju H, Liu Z, Ning Q, Zhang J, Zhao X, Huang Y, Ma Z, Li Y. Bioinformatics resources and tools for conformational B-cell epitope prediction. Comput Math Methods Med. 2013;2013:943636. DOI: 10.1155/2013/943636 - 79.
Greenbaum JA, Andersen PH, Blythe M, Bui HH, Cachau RE, Crowe J, Davies M, Kolaskar AS7, Lund O, Morrison S, Mumey B, Ofran Y, Pellequer JL, Pinilla C, Ponomarenko JV, Raghava GPS, Van Regenmortel MHV, Roggen EL, Sette A, Schlessinger A, Sollner J, Zand M, Peters B. Towards a consensus on datasets and evaluation metrics for developing B-cell epitope prediction tools. J Mol Recognit. 2007;20:75–82. DOI: 10.1002/jmr.815 - 80.
Yao B, Zheng D, Liang S, Zhang C. Conformational B-cell epitope prediction on antigen protein structures: A review of current algorithms and comparison with common binding site prediction methods. PLoS One. 2013;8(4):e62249. DOI: 10.1371/journal.pone.0062249 - 81.
Greenfield EA, DeCaprio J, Brahmandam M. Selecting the antigen. In: Greenfield EA, editor. Antibodies: A laboratory manual. 2nd ed. New York: Cold Spring Harbor Press; 2013. p. 43–106. - 82.
Moore ML, Grant GA. Peptide design considerations. In: Grant GA, editor. Synthetic peptide: A user’s guide. 2nd ed. New York: Oxford; 2002. p. 10–92. - 83.
Davies DH, Halablab MA, Clarker J, Cox FEG, Young TWK. Infection and Immunity. 1st ed. London: Taylor & Francis; 2003. 237. - 84.
Gómara MJ, Haro I. Synthetic peptides for the immunodiagnosis of human diseases. Curr Med Chem. 2007;14(5):531–546. - 85.
Wu CL, Leu TS, Chang TT, Shiau AL. Hepatitis C virus core protein fused to hepatitis B virus core antigen for serological diagnosis of both hepatitis C and hepatitis B infections by ELISA. J Med Virol. 1999;57(2):104–110. - 86.
Hans D, Young PR, Fairlie DP. Current status of short synthetic peptides as vaccines. Med Chem. 2006;2(6):627–646. - 87.
El Awady MK, El-Demellawy MA, Khalil SB, Galal D, Goueli SA. Synthetic peptide-based immunoassay as a supplemental test for HCV infection. Clin Chim Acta. 2002;325(1–2):39–46. DOI: 10.1016/S0009-8981(02)00245-0 - 88.
Favorov MO, Khudyakov YE, Fields HA, Khudyakova NS, Padhye N, Alter MJ, Mast E, Polish L, Yashina TL, Yarasheva DM, Onischenkob GG, Margolis HS. Enzyme immunoassay for the detection of antibody to hepatitis E virus based on synthetic peptides. J Virol Methods. 1994;46(2):237–250. - 89.
Gevorkian G, Soler C, Viveros M, Padilla A, Govezensky T, Larralde C. Serologic reactivity of a synthetic peptide from human immunodeficiency virus type 1 gp41 with sera from a Mexican population. Clin Diagn Lab Immunol. 1996;3(6):651–653. - 90.
Gnann JW Jr, McCormick JB, Mitchell S, Nelson JA, Oldstone MB. Synthetic peptide immunoassay distinguishes HIV type 1 and HIV type 2 infections. Science. 1987;237(4820):1346–1349. - 91.
Hernández M, Beltrán C, García E, Fragoso G, Gevorkian G, Fleury A, Parkhouse M, Harrison L, Sotelo J, Sciutto E. Cysticercosis: Towards the design of a diagnostic kit based on synthetic peptides. Immunol Lett. 2000;71(1):13–17. DOI: 10.1016/S0165-2478(99)00166-2 - 92.
Mahler M, Blüthner M, Pollard KM. Advances in B-cell epitope analysis of autoantigens in connective tissue diseases. Clin Immunol. 2003;107(2):65–79. DOI: 10.1016/S1521-6616(03)00037-8 - 93.
Shin SY, Lee MK, Kim SY, Jang SY, Hahm KS. The use of multiple antigenic peptide (MAP) in the immunodiagnosis of human immunodeficiency virus infection. Biochem Mol Biol Int. 1997;43(4):713–721. - 94.
Chan PK, To WK, Liu EY, Ng TK, Tam JS, Sung JJ, Lacroix JM, Houde M. Evaluation of a peptide-based enzyme immunoassay for anti-SARS coronavirus IgG antibody. J Med Virol. 2004;74(4):517–520. DOI: 10.1002/jmv.20207 - 95.
Fachiroh J, Paramita DK, Hariwiyanto B, Harijadi A, Dahlia HL, Indrasari SR, Kusumo H, Zeng YS, Schouten T, Mubarika S, Middeldorp JM. Single-assay combination of Epstein-Barr Virus (EBV) EBNA1- and viral capsid antigen-p18-derived synthetic peptides for measuring anti-EBV immunoglobulin G (IgG) and IgA antibody levels in sera from nasopharyngeal carcinoma patients: Options for field screening. J Clin Microbiol. 2006;44(4):1459–1467. DOI: 10.1128/JCM.44.4.1459-1467.2006 - 96.
Schellekens GA, Visser H, de Jong BA, van den Hoogen FH, Hazes JM, Breedveld FC, van Venrooij WJ. The diagnostic properties of rheumatoid arthritis antibodies recognizing a cyclic citrullinated peptide. Arthritis Rheum. 2000;43(1):155–163. - 97.
Yoshida CF, Rouzerè CD, Nogueira RM, Lampe E, Travassos-da-Rosa MA, Vanderborght BO, Schatzmayr HG. Human antibodies to dengue and yellow fever do not react in diagnostic assays for hepatitis C virus. Braz J Med Biol Res. 1992;25(11):1131–1135. - 98.
Araujo Z, Giampietro F, Bochichio Mde L, Palacios A, Dinis J, Isern J, Waard JH, Rada E, Borges R, Fernández de Larrea C, Villasmil A, Vanegas M, Enciso-Moreno JA, Patarroyo MA. Immunologic evaluation and validation of methods using synthetic peptides derived from Mycobacterium tuberculosis for the diagnosis of tuberculosis infection. Mem Inst Oswaldo Cruz. 2013;108(2):131–139. DOI: 10.1590/0074-0276108022013001 - 99.
Bottino CG, Gomes LP, Pereira JB, Coura JR, Provance DW Jr, De-Simone SG. Chagas disease-specific antigens: Characterization of epitopes in CRA/FRA by synthetic peptide mapping and evaluation by ELISA-peptide assay. BMC Infect Dis. 2013;13:568. DOI: 10.1186/1471-2334-13-568 - 100.
Caldini CP, Xander P, Kioshima ÉS, Bachi AL, de Camargo ZP, Mariano M, Lopes JD. Synthetic peptides mimic gp75 from Paracoccidioides brasiliensis in the diagnosis of paracoccidioidomycosis. Mycopathologia. 2012;174(1):1–10. DOI: 10.1007/s11046-011-9518-3 - 101.
Faria AR, Costa MM, Giusta MS, Grimaldi G Jr, Penido ML, Gazzinelli RT, Andrade HM. High-throughput analysis of synthetic peptides for the immunodiagnosis of canine visceral leishmaniasis. PLoS Negl Trop Dis. 2011;5(9):e1310. DOI: 10.1371/journal.pntd.0001310 - 102.
Gori A, Longhi R, Peri C, Colombo G. Peptides for immunological purposes: Design, strategies and applications. Amino Acids. 2013;45(2):257–268. DOI: 10.1007/s00726-013-1526-9 - 103.
Shen G, Behera D, Bhalla M, Nadas A, Laal S. Peptide-based antibody detection for tuberculosis diagnosis. Clin Vaccine Immunol. 2009;16(1):49-54. DOI: 10.1128/CVI.00334-08 - 104.
Martins LM, de Andrade HM, Vainstein MH, Wanke B, Schrank A, Balaguez CB, dos Santos PR, Santi L, Pires Sda F, da Silva AS, de Castro JA, Brandão RM, do Monte SJ. Immunoproteomics and immunoinformatics analysis of Cryptococcus gattii: Novel candidate antigens for diagnosis. Future Microbiol. 2013;8(4):549–563. DOI: 10.2217/fmb.13.22 - 105.
de Serpa Brandão RM, Soares Martins LM, de Andrade HM, Faria AR, Soares Leal MJ, da Silva AS, Wanke B, dos Santos Lazéra M, Vainstein MH, Mendes RP, Moris DV, de Souza Cavalcante R, do Monte SJ. Immunoreactivity of synthetic peptides derived from proteins of Cryptococcus gattii. Future Microbiol. 2014;9(7):871–878. DOI: 10.2217/fmb.14.49 - 106.
McMullan BJ, Halliday C, Sorrell TC, Judd D, Sleiman S, Marriott D, Olma T, Chen SC. Clinical utility of the cryptococcal antigen lateral flow assay in a diagnostic mycology laboratory. PLoS One. 2012;7(11):e49541. DOI: 10.1371/journal.pone.0049541. - 107.
Eroles P, Sentandreu M, Elorza MV, Sentandreu R. The highly immunogenic enolase and Hsp70p are adventitious Candida albicans cell wall proteins. Microbiology. 1997;143:313–320. DOI: 10.1099/00221287-143-2-31 - 108.
Burnie JP, Matthews RC. Heat shock protein 88 and Aspergillus infection. J Clin Microbiol. 1991;29(10):2099–2106. - 109.
Gomez FJ, Gomez AM, Deepe GS Jr. An 80-kilodalton antigen from Histoplasma capsulatum that has homology to heat shock protein 70 induces cell-mediated immune responses and protection in mice. Infect Immun. 1992;60(7):2565–2571. - 110.
Deepe GS Jr, Gibbons RS. Cellular and molecular regulation of vaccination with heat shock protein 60 from Histoplasma capsulatum. Infect Immun. 2002;70(7):3759–3767. - 111.
Kakeya H, Udono H, Ikuno N, Yamamoto Y, Mitsutake K, Miyazaki T, Tomono K, Koga H, Tashiro T, Nakayama E, Kohno S. A 77-kilodalton protein of Cryptococcus neoformans, a member of the heat shock protein 70 family, is a major antigen detected in the sera of mice with pulmonary cryptococcosis. Infect Immun. 1997;65(5):1653–1658. - 112.
Kakeya H, Udono H, Maesaki S, Sasaki E, Kawamura S, Hossain MA, Yamamoto Y, Sawai T, Fukuda M, Mitsutake K, Miyazaki Y, Tomono K, Tashiro T, Nakayama E, Kohno S. Heat shock protein 70 (hsp70) as a major target of the antibody response in patients with pulmonary cryptococcosis. Clin Exp Immunol. 1999;15(3):485–490. DOI: 10.1046/j.1365-2249.1999.00821.x - 113.
Silveira CP, Piffer AC, Kmetzsch L, Fonseca FL, Soares DA, Staats CC, Rodrigues ML, Schrank A, Vainstein MH. The heat shock protein (Hsp) 70 of Cryptococcus neoformans is associated with the fungal cell surface and influences the interaction between yeast and host cells. Fungal Genet Biol. 2013;60:53–63. DOI: 10.1016/j.fgb.2013.08.005 - 114.
Dai J, Jiang M, Wang Y, Qu L, Gong R, Si J. Evaluation of a recombinant multiepitope peptide for serodiagnosis of Toxoplasma gondii infection. Clin Vaccine Immunol. 2012;19(3):338–342. DOI: 10.1128/CVI.05553-11 - 115.
Camussone C, Gonzalez V, Belluzo MS, Pujato N, Ribone ME, Lagier CM, Marcipar IS. Comparison of recombinant Trypanosoma cruzi peptide mixtures versus multiepitope chimeric proteins as sensitizing antigens for immunodiagnosis. Clin Vaccine Immunol. 2009;16(6):899–905. DOI: 10.1128/CVI.00005-09 - 116.
Faria AR, de Castro Veloso L, Coura-Vital W, Reis AB, Damasceno LM, Gazzinelli RT, Andrade HM. Novel recombinant multiepitope proteins for the diagnosis of asymptomatic leishmania infantum-infected dogs. PLoS Negl Trop Dis. 2015;9(1):e3429. DOI: 10.1371/journal.pntd.0003429 - 117.
Cheng Z, Zhao JW, Sun ZQ, Song YZ, Sun QW, Zhang XY, Zhang XL, Wang HH, Guo XK, Liu YF, Zhang SL. Evaluation of a novel fusion protein antigen for rapid serodiagnosis of tuberculosis. J Clin Lab Anal. 2011;25(5):344–349. DOI: 10.1002/jcla.20483 - 118.
Duthie MS, Hay MN, Morales CZ, Carter L, Mohamath R, Ito L, Oyafuso LK, Manini MI, Balagon MV, Tan EV, Saunderson PR, Reed SG, Carter D. Rational design and evaluation of a multiepitope chimeric fusion protein with the potential for leprosy diagnosis. Clin Vaccine Immunol. 2010;17(2):298–303. DOI: 10.1128/CVI.00400-09