Antigenic characterization of Cryptococcus neoformans serotypes and its application to serotyping of clinical isolates

Cryptococcosis in a bottlenose dolphin (Tursiops truncatus) caused by Cryptococcus neoformans var. gattii

We describe the first case of cryptococcosis caused by Cryptococcus neoformans var. gattii in a male Atlantic bottlenose dolphin (Tursiops truncatus). The dolphin showed clinical signs of tachypnea, transient dyspnea, and mild tachycardia and developed multiple hyperechoic nodules, parenchymal consolidation, and thickening of pleura. A diagnosis of bronchopneumonia with pleuritis was made. Itraconazole therapy was implemented for 120 days, and trough levels in serum were within or above the suggested therapeutic range. Titers of cryptococcal antigen in serum increased eightfold during therapy, and the case had a fatal outcome. Necropsy examination findings included enlarged pulmonary lymph nodes and extensive coalescing granulomatous lesions throughout both lungs. Histologic examination revealed numerous, spherical to ellipsoidal, mucicarmine-positive, 3- to 14-microm, encapsulated, budding cells consistent with C. neoformans. Culture of the lung tissue yielded colonies of C. neoformans. The isolate was urease positive and nitrate negative and exhibited phenoloxidase activity. It was positive on canavanine-glycine-bromothymol blue agar. When tested by the Iatron serodiagnostic reagent kit (Iatron Laboratories, Inc.), it was shown to belong to serotype B.

Intraspecies diversity of Cryptococcus albidus isolated from humans as revealed by sequences of the internal transcribed spacer regions

The basidiomycetous yeast, Cryptococcus albidus, shows intraspecies diversity, but it is rarely isolated from immunocompromised patients. Nineteen strains of C. albidus, including nine clinical isolates, were re-classified by sequences of their rRNA internal transcribed spacer (ITS) regions. The nine clinical isolates were genetically diverse and included both C. albidus and C. diffluens. One clinical isolate, recovered from the blood of an AIDS patient, represented a new species. Only small differences were found in the biochemical and serological characteristics of C. albidus and C. diffluens. All isolates were sensitive to amphotericin B, but several isolates were resistant to fluconazole and itraconazole. C. albidus heterogeneity should be taken into consideration when identifying clinical isolates.

An immunohistochemical method that differentiates Cryptococcus neoformans varieties and serotypes in formalin-fixed paraffin-embedded tissues

An immunohistochemical method for determining the variety of Cryptococcus neoformans in formalin-fixed paraffin-embedded tissues was developed using mAbs 471, 302 and CRND8. The method was validated primarily using veterinary patients for which both formalin-fixed lesions and a cultured isolate were available. L-Canavanine glycine bromothymol blue (CGB) agar and the 'Crypto-Check' kit were used to determine the variety and serotype, respectively, of cultured isolates. Immunohistochemistry accurately predicted the C. neoformans variety in all tissue specimens. The CGB agar method of determining C. neoformans variety gave the same result as immunohistochemistry for 30/31 specimens. For the single discordant isolate, the serotype, random amplification of polymorphic DNA profile, microscopic and colony morphology all supported the immunohistochemical staining pattern in suggesting C. neoformans var. gattii; however, the CGB agar result was at variance. Of the C. neoformans var. neoformans cases, immunohistochemistry was congruent with variety for 13/13 cases and with serotyping for 10/13 cases. The three discordant cases were classified as having some serotype D reactivity by immunohistochemistry, but were considered to be serotype A using the Crypto-Check kit. This new method should prove a valuable epidemiological tool in studies of cryptococcosis, especially in the veterinary setting where archival tissue specimens may exist but corresponding mycological data is typically absent. The versatility of this method will expand in the future as other monoclonal antibodies with different specificities are developed.

Isolation of a Cryptococcus neoformans serotype A MATa strain from the Italian environment

Cryptococcus neoformans is a heterothallic basidiomycete which possesses a bipolar mating system based on two mating type alleles, MATa and MATalpha. In the type variety, C. neoformans var. neoformans, both mating types have been found among strains of one serotype, serotype D, whereas only MATalpha was identified after extensive survey of serotype A strains. Serotype A MA Ta appeared to be extinct or to exist only in a vestigial, non-functional form. We report the isolation of a C. n. var. neoformans serotype A MATa strain from the Italian environment. The strain was serotyped by slide agglutination test, genotyped by polymerase chain reaction (PCR) fingerprinting using the (GACA)4 primer, and its haploid state was determined by flow cytometry. The mating type was identified by PCR amplification of the pheromone a gene. In addition, the amplification of the four STE20 alleles, specific for the mating type of serotypes A and D, showed that the strain contains only the MATa locus. By crossing experiments the strain was found to be fertile. The interest in the finding of this fertile isolate is related to the possibility to construct a congenic pair of serotype A MATa/MATalpha strains to be used in genetic and pathogenesis studies.

Hybrid genotypes in the pathogenic yeast Cryptococcus neoformans

Amplified fragment length polymorphism (AFLP) genotyping of isolates of the pathogenic fungus Cryptococcus neoformans suggested a considerable genetic divergence between the varieties C. neoformans var. neoformans and C. neoformans var. grubii on the one hand versus C. neoformans var. gattii on the other. This divergence is supported by additional phenotypic, biochemical, clinical and molecular differences. Therefore, the authors propose the existence of two species, C. neoformans (Sanfelice) Vuillemin and C. bacillisporus Kwon-Chung, which differ in geographical distribution, serotypes and ecological origin. Within each species three AFLP genotypes occur, which differ in geographical distribution and serotypes. Differences in ecological origin (AIDS patients, non-AIDS patients, animals or the environment) were found to be statistically not significant. In C. neoformans as well as in C. bacillisporus one of the genotypes represented a hybrid. The occurrence of hybridization has consequences for the reproductive biology of the species, as new genotypes with altered virulence or susceptibility to antifungal drugs may arise through the exchange of genetic material.

Capsular reactions of Cryptococcus neoformans with polyspecific and oligospecific polyclonal anticapsular antibodies

Monoclonal antibodies to the capsular polysaccharide of Cryptococcus neoformans produce distinct capsular reactions and have biological activities that are determined by serotype specificity. In the present study, polyclonal rabbit anticapsular antibodies were cross-absorbed to produce serotype specificities similar to those of monoclonal antibodies. The results showed that polyclonal and monoclonal antibodies with similar serotype specificities have similar capsular reactions and biological activities.

Serological relationships of Cryptococcus spp.: distribution of antigenic factors in Cryptococcus and intraspecies diversity

The antigenic formulas of 34 species in the genus Cryptococcus were determined by using type strains and eight factor sera prepared from adsorption experiments with Cryptococcus neoformans serotypes. These antigenic factors were shared by 19 species. The strains used could be divided into eight serological groups. The patterns of groups 1, 2, 3, 5, and 6 were the same as the patterns of C. neoformans serotypes A, D, A-D, B, and C, respectively. The species belonging to group 4 reacted to factor sera 1, 2, and 3. Group 7 contained one species that reacted only to factor serum 1. The 15 species in group 8 did not react to any of the factor sera used. Compared to the reported molecular phylogenetic tree, the serological and phylogenetic data were correlated in the Filobasidium lineage. All the members of the albidus clade in the Filobasidium lineage had antigens 1, 2, and 3, and all the strains in the magnus clade belonged to serogroup 8. Moreover, intraspecies diversity was examined using strains of C. curvatus, C. humicolus, and C. laurentii. Serological heterogeneity was observed in the species C. humicolus and C. laurentii, as well as in phylogenetic relationships previously published. Using serological features, similarities and differences between Cryptococcus species were demonstrated. Our study contributes to a better description of the genus Cryptococcus and related species phenotypically and phylogenetically.

Environmental isolation of Cryptococcus neoformans var. gattii and C. neoformans var. neoformans in the city of São Paulo, Brazil

In order to determine the environmental occurrence of both varieties of Cryptococcus neoformans in the city of São Paulo, pigeon droppings and vegetable material from trees of the genus Eucalyptus were collected at typically crowded places. A total of 38 sites downtown where large heaps of pigeon droppings could be found were selected for sampling. Pigeon droppings from 10 (26.3%) of these sites were positive for C. neoformans var. neoformans in at least one sample. Twelve eucalyptus woods located within four municipal parks were also surveyed; vegetable material from Eucalyptus spp. trees were collected monthly over a 2-year period. C. neoformans var. gattii was recovered from a wood in Ibirapuera Park during the same season on two different occasions (November 1996 and November 1997); this park contained specimens of Eucalyptus camaldulensis, a natural habitat of C. n. var. gattii. C. n. var. neoformans was detected in a wood in Ibirapuera Park and Aclimação Park. The results show that both C. n. var. neoformans and C. n. var. gattii are present in the urban environment of São Paulo city at sites where large numbers of people normally gather.

Anti-Cryptococcus activity of combination of extracts of Cassia alata and Ocimum sanctum

The paper reports the anti-Cryptococcus activity of combination of ethanolic extracts of leaves of Cassia alata and Ocimum sanctum. The activity of combination of the extracts was heat-stable and worked at acidic pH.

Case report. Meningitis due to Cryptococcus neoformans var. neoformans serotype AD associated with pulmonary tuberculosis

A case of meningitis in a 38-year old male with pulmonary tuberculosis is described. Cryptococcus neoformans was isolated from the cerebrospinal fluid. The isolate belonged to variety neoformans serotype AD. The patient died before any antimycotic therapy could be instituted.

Prevalence of Cryptococcus neoformans var. neoformans (Serotype D) and Cryptococcus neoformans var. grubii (Serotype A) isolates in New York City

Analysis of 40 New York City Cryptococcus neoformans isolates revealed that 39 were typeable, of which 85 and 12.5% were Cryptococcus neoformans var. grubii (serotype A) and Cryptococcus neoformans var. neoformans (serotype D), respectively. The prevalence of serotype D isolates in New York City appears to be significantly higher than indicated by previous studies of North American isolates.

Clinical features and in vitro susceptibilities of two varieties of Cryptococcus neoformans in Taiwan

One hundred years after introduction of the Eucalyptus tree to Taiwan, a predominantly subtropical island, we analyzed clinical and microbiological data of 59 patients with Cryptococcus neoformans infection hospitalized at National Taiwan University Hospital during 1982 to 1997. There were 38 (64.4%) cases of cryptococcosis caused by the var. neoformans and 21 (35.6%) caused by the var. gattii. Thirty-three patients (55.9%) had impaired T cell function, which included 12 patients with acquired immunodeficiency syndrome (AIDS). Eleven of the 12 patients with AIDS were diagnosed after 1995, and 11 cases were caused by var. neoformans. Minimum inhibitory concentrations (MICs) determined by the NCCLS broth microdilution method using antibiotic medium 3 improved the discrimination of in vitro susceptibility against amphotericin B and demonstrated that var. gattii isolates were less susceptible (geometric means 0.25 microg/ml versus 0.64 microg/ml, P < 0.001). In addition, a higher proportion of var. gattii were less susceptible to flucytosine as compared with var. neoformans (35.0% versus 64.9%, P = 0.030). There was no seasonal clustering for isolation of var. neoformans, though infections caused by var. gattii peaked in July and August. Compared with the first study of cryptococcosis (1957-1972) at NTUH, this study demonstrated the increase in immunocompromised and elderly patients, as well as a higher proportion of Cryptococcus isolated from blood or bone marrow. Facing the increasing adaptive plantation of Eucalyptus in Taiwan, the importance of field study regarding the role of Eucalyptus plantations in Taiwan and occurrence of cryptococcosis in human beings cannot be over-emphasized.

Cryptococcus albidus-induced summer-type hypersensitivity pneumonitis

We studied summer-type hypersensitivity pneumonitis believed to be induced by Cryptococcus albidus in the home environments of the patients. All patients had antibodies that were reactive to Cryptococcus neoformans and Trichosporon cutaneum in sera and bronchoalveolar lavage (BAL) fluids. Cryptococcus albidus strains were isolated from 62.5% of the patient home environments. Trichosporon cutaneum was found in none of the patient homes. To study local antibody production in the lung, we cultured BAL cells to measure anti-C. neoformans and anti-T. cutaneum antibodies in the culture supernatants by the ELISA method. IgG, IgA, and IgM anti-Cryptococcus and anti-Trichosporon antibodies were found in all culture supernatants. A significant correlation was observed in antibody binding activity between Cryptococcus and Trichosporon antigen. However, the amount of IgA and IgM antibody bound to C. neoformans was significantly higher than was bound to T. cutaneum. Most anti-Cryptococcus and anti-Trichosporon antibody was absorbed by C. albidus. Our results suggest that C. albidus may be an etiologic agent in most of the cases we studied, and that IgA and IgM antibody in BAL fluid may be secreted by plasma cells in the lung.

Serotyping of Cryptococcus neoformans isolates from clinical and environmental sources in Spain

We determined biovars and serotypes of 154 isolates of Cryptococcus neoformans from clinical and environmental sources from different areas of Spain. All clinical isolates belonged to C. neoformans var. neoformans. Serotypes showed an irregular distribution. C. neoformans var. gattii serotype B was isolated from necropsy specimens from goats with pulmonary disease.

Cryptococcus neoformans var. grubii: separate varietal status for Cryptococcus neoformans serotype A isolates

Cryptococcus neoformans var. neoformans presently includes isolates which have been determined by the immunologic reactivity of their capsular polysaccharides to be serotype A and those which have been determined to be serotype D. However, recent analyses of the URA5 sequences and DNA fingerprinting patterns suggest significant genetic differences between the two serotypes. Therefore, we propose to recognize these genotypic distinctions, as well as previously reported phenotypic differences, by restricting C. neoformans var. neoformans to isolates which are serotype D and describing a new variety, C. neoformans var. grubii, for serotype A isolates.

Phenotypic and genotypic differentiation of several human and avian isolates of Cryptococcus neoformans

The Cryptococcus neoformans strains isolated from two human cases could be diagnosed as Cr. neoformans var. neoformans by differentiation on the basis of their characteristics determined by proline, canavanine and EDTA urease tests. The results of the serovar assignment were: for the isolate from the meningoencephalitis patient with lethal outcome, serovar A; for the strain isolated from the osteomyelitis patient with benign course, serovar D. Also, the PCR fingerprinting using primers (GACA)4, (CAC)5 and FM 1 resulted in a clear and reproducible assignment of the Cr. neoformans strains to the varieties neoformans and gattii, respectively, and, in addition, it confirmed the serovar assignment. No statistically confirmed differences in virulence between the osteomyelitis and the meningoencephalitis strain could be established by i.v. testing in mice, nor did the PCR with several primers provide any clues to a genetically determined higher virulence of the meningoencephalitis strain. The different classification as serovars A and D does not allow any conclusions concerning different virulence. It was not possible to retrospectively establish the sources of infection of the two Cr. neoformans infections, but pigeon faeces may well have played a role as a reservoir for one of the illnesses.

Isolation of Cryptococcus neoformans from pigeon (Columbia livia droppings in northern Iran

Nine hundred and eighty three specimens of pigeon droppings, collected in different regions of northern Iran, were examined. Of these samples, 175 (17.8%) were positive for Cryptococcus neoformans. All isolates obtained were C. neoformans var. neoformans. Most of these isolates of C. neoformans were from pigeon shelters. There were significant differences in isolation frequency between pigeon shelters and the other collection sites.

Cryptococcus neoformans chemotyping by quantitative analysis of 1H nuclear magnetic resonance spectra of glucuronoxylomannans with a computer-simulated artificial neural network

The complete assignment of the proton chemical shifts obtained by nuclear magnetic resonance (NMR) spectroscopy of de-O-acetylated glucuronoxylomannans (GXMs) from Cryptococcus neoformans permitted the high-resolution determination of the total structure of any GXM. Six structural motifs based on an alpha-(1-->3)-mannotriose substituted with variable quantities of 2-O-beta- and 4-O-beta-xylopyranosyl and 2-O-beta-glucopyranosyluronic acid were identified. The chemical shifts of only the anomeric protons of the mannosyl residues served as structure reporter groups (SRG) for the identification and quantitation of the six triads present in any GXM. The assigned protons for the mannosyl residues resonated at clearly distinguishable positions in the spectrum and supplied all the information essential for the assignment of the complete GXM structure. This technique for assigning structure is referred to as the SRG concept. The SRG concept was used to analyze the distribution of the six mannosyl triads of GXMs obtained from 106 isolates of C. neoformans. The six mannosyl triads occurred singularly or in combination with one or more of the other triads. The identification and quantitation of the SRG were simplified by using a computer-simulated artificial neural network (ANN) to automatically analyze the SRG region of the one-dimensional proton NMR spectra. The occurrence and relative distribution of the six mannosyl triads were used to chemotype C. neoformans on the basis of subtle variations in GXM structure determined by analysis of the SRG region of the proton NMR spectrum by the ANN. The data for the distribution of the six SRGs from GXMs of 106 isolates of C. neoformans yielded eight chemotypes, Chem1 through Chem8.

First identification of autochthonous Cryptococcus neoformans var. gattii isloated from goats with predominantly severe pulmonary disease in Spain

Cryptococcus neoformans var. gattii is associated with Eucalyptus trees growing in various tropical and subtropical regions of the world. The identification of 13 autochthonous strains of C. neoformans var. gattii in Spain is reported. These strains were isolated from lung (10 samples), liver (1 sample), and brain (2 samples) tissue specimens from six goats suffering from predominantly severe pulmonary disease that were autopsied. The animals were members of five different herds of goats grazing in rural areas of the province of Cáceres (Extremadura, Spain). Between 1990 and 1994, there were five outbreaks, in which between 2.5 and 12% of the goats were affected. Although respiratory symptoms (pneumonia) associated with cachexia were the predominant clinical picture in all outbreaks, brain and liver involvement was also documented in three of the five outbreaks. Biotyping was performed by culturing the isolates on L-canavanine-glycine-bromothymol blue medium and testing them for the assimilation of D-proline and D-tryptophan. Serotyping by agglutination tests confirmed the characterization of all strains as C. neoformans var. gattii serotype B. This is the first confirmation of the presence of this variety in Spain, with a peculiar ability to produce severe pulmonary and systemic disease in normal goats, particularly in the form of outbreaks of pneumonia in association with cachexia.

Isolates of Cryptococcus neoformans serotype A and D developed on canavanine-glycine-bromthymol blue medium

Two isolates of Cryptococcus neoformans serotype A and one isolate of serotype D from pigeon droppings were found to grow on canavanine-glycine-bromthymol blue (CGB) medium, when the Japanese isolates of Cr. neoformans were examined for their serotype and biochemical characteristics. The susceptibility to canavanine and the activity in assimilation of glycine were analysed on these three isolates. They were resistant to canavanine at the high concentration of 3.6 mmol l-1 and developed by assimilating the glycine even at a concentration of 7 mmol l-1. These isolates were proved to develop well on CGB medium, which contains 0.1 mmol l-1 of canavanine and 133 mmol l-1 of glycine. Three isolates of Cr. neoformans developed on CGB medium were also confirmed to be serotype A or D by the molecular analysis.

Prevalence of serotype D in Cryptococcus neoformans isolates from HIV positive and HIV negative patients in Italy

Cryptococcus neoformans strains isolated from 207 HIV positive and HIV negative patients hospitalized in Northern Italy were serotyped by slide agglutination. One Brazilian HIV negative woman was infected by var. gattii serotype B and all the other patients by var. neoformans, serotype D in 71%, serotype A in 24.6% and serotype AD in 3.4%. No difference was observed between subjects with serotypes A and D in HIV coinfection, exposure categories for AIDS, age, sex, and CD4 count of HIV positive patients. Meningeal and respiratory tract involvements and prostatic reservoir occurred with comparable frequency in AIDS patients infected by serotypes A and D. Skin lesions were observed only in serotype D infections, occurring in 12.6% of HIV positive and 58.3% of HIV negative patients infected by this serotype. Serotype A was found less susceptible to fluconazole than serotype D: 53.7% of serotype A strains had a MIC > or = 25 micrograms ml-1 compared to 17.7% of the serotype D isolates. On the other hand, both serotypes were highly susceptible to itraconazole.

Structure of the 13C-enriched O-deacetylated glucuronoxylomannan of Cryptococcus neoformans serotype A determined by NMR spectroscopy

The complete assignment of 1H and 13C chemical shifts for 99% uniformly 13C-labeled O-deacetylated glucuronoxylomannan (GXM) of Cryptococcus neoformans serotype A isolate 9759-Mu-1 was accomplished by the analysis of HCCH-TOCSY and HCCH-COSY spectra. The sequence of the glycosyl residues was determined by a GHMBC experiment using 20% uniformly 13C-labeled GXM; GXM was prepared by a novel procedure that insured the virtual exclusion of adjacent 13C-labeled carbon atoms. For each residue in the GXM of 9759-Mu-1 we determined its linkage position, its anomeric configuration, and its position in the repeating sequence as follows: [sequence: see text]

Reactivity patterns and epitope specificities of anti-Cryptococcus neoformans monoclonal antibodies by enzyme-linked immunosorbent assay and dot enzyme assay

Cryptococcus neoformans glucuronoxylomannans (GXM) are capsular polysaccharides important for virulence in cryptococcosis. This study used dot enzyme assays (DEA) and enzyme-linked immunosorbent assays (ELISA) to determine the reactivity patterns of 21 murine monoclonal antibodies (MAbs) with structurally defined GXMs from five serotypes. The MAbs were categorized into eight groups on the basis of DEA and five groups on the basis of ELISA. MAbs 302, 339, and 439 were studied extensively for their binding to various native and chemically modified GXMs. Quantitative variation in the inhibitory effects of GXMs on the binding of MAbs 302, 339, and 439 were observed by competitive ELISA. O-Deacetylation of serotype A, B, and D GXM resulted in the complete loss of their inhibitory properties. Carboxyl group reduction of GXMs from serotypes A and D resulted in a significant decrease of inhibitory activity for MAb. Xylomannans and methyl glycosides exhibited no detectable inhibitory activity on MAb binding to GXM. The results indicate (i) the existence of five to eight MAb-defined distinct epitopes in C. neoformans GXM that can elicit antibody responses, (ii) MAb detection of antigenic variation within GXMs assigned to a particular serotype, (iii) good correspondence between the patterns of MAb reactivities and polyclonal rabbit factor sera, (iv) good agreement between MAb molecular structure and serotype reactivity, and (v) a dependence of the serotype reactivity profile for a given MAb on the technique used to measure binding.

Assignment and serotyping of Trichosporon species: the causative agents of summer-type hypersensitivity pneumonitis

We re-valued three antigenic types within the genus Trichosporon as the causative agents of summer-type hypersensitivity pneumonitis (SHP). Corresponding standard strains, TIMM 1573 (serotype I), TIMM 1318 (serotype II), and M9456 (serotype III) were assigned to species T. mucoides, T. asahii and T. montevideense, respectively, based on 95% or more DNA/DNA relatedness with each type of culture and other genetical, physiological and morphological characteristics. To confirm the significance of these serotypes, 98 other strains of Trichosporon isolated from patients' environments and 24 CBS strains, including type cultures of species described within the genus, were serotyped. Serum antibody analysis of 220 SHP patients against Trichosporon spp. were also examined to estimate the antigenic profile of SHP. The present results indicate that T. asahii and T. mucoides, which are the most common causes of trichosporonosis, appear to be the major causative agents of SHP. These observations suggest a common pathogenesis of Trichosporon inducing hypersensitivity and infection, depending on the immunological status of the host.

Serological characterization of Trichosporon cutaneum and related species

Recent molecular biological, chemical, physiological and morphological studies indicate that Tri-chosporon cutaneum and related species should be reclassified. In this study, antigenic characteristics of the species were determined. The results of adsorption experiments revealed that there were at least three serological types: I, II and III. Specific factor sera I, II and III were prepared on the basis of adsorption experiments and isolates were serotyped by cell slide agglutination (CSA). Since the CSA test was difficult to read in some strains, the results of the CSA test were compared with the findings from an enzyme-linked immunosorbent assay (ELISA). For the ELISA, crude polysaccharide antigens prepared from the culture supernatant were used as the antigen. The types determined by ELISA correlated well with those determined by the CSA test. These data suggest that T. cutaneum and related species have at least three serological types, and that the typing can be done by either CSA or ELISA.

Structure of the O-deacetylated glucuronoxylomannan from Cryptococcus neoformans Cap70 as determined by 2D NMR spectroscopy

Cryptococcus neoformans, an opportunistic pathogen, is the fourth leading cause of death among AIDS patients. The yeast's capsule is a major virulence factor, and serotype is related to the chemical structure of glucuronoxylomannan (GXM), its capsular polysaccharide. The GXM from Cap70, a hypocapsular mutant of serotype D isolate B-3501, was investigated by chemical analysis and 2D NMR spectroscopy. The assignment of 1H and 13C chemical shifts for the O-deacetylated polysaccharide was accomplished from the analysis of DQF-COSY, TOCSY, and gradient-enhanced HSQC spectra. The sequence and linkage positions of glycosyl residues were determined by NOESY and ROESY spectra. Two repeating polysaccharide components were identified as having the following structures in approximately equal proportions: [formula: see text] It is not known if these repeating units comprise a single or two separate polymer chains. Pentasaccharide 2 has been known to be the major GXM polymer of B-3501 and other serotype D isolates. Hexasaccharide 1 is identified for the first time although it has subsequently been identified in other C. neoformans isolates. The presence of 1 in the GXM of Cap70 is consistent with the extra xylose found relative to that in isolate B-3501. The mannose:xylose:glucuronic acid:O-acetyl molar ratio of Cap70 GXM is 3.00:1.73:0.78:1.75, while the same ratio for B-3501 and other serotype D isolates is approximately 3.00:1.00:0.80:1.75. Methylation analysis confirmed that the GXM of Cap70 contains unsubstituted, monosubstituted (2-linked), and disubstituted (2- and 4-linked) mannose in a ratio of 0.87:1.75:0.38. Dot blot immunoassay indicates that Cap70 is a serotype D isolate like its parent strain.

Serotyping of Cryptococcus neoformans by dot enzyme assay

A method is described for the serotyping of Cryptococcus neoformans based on direct analysis of culture supernatants for the major type-specific capsular antigen, glucuronoxylomannan. Factor sera prepared by absorption of polyclonal rabbit antisera (Iatron Laboratories, Inc., Tokyo, Japan) or selected anti-C. neoformans monoclonal antibodies were used in a dot enzyme assay to detect the presence of antigen.

Production of agglutinating monoclonal antibody against antigen 8 specific for Cryptococcus neoformans serotype D

A hybridoma (clone CRND-8) that produced agglutinating monoclonal antibody (MAb) against Cryptococcus neoformans serotype D was established by using a soluble capsular polysaccharide-keyhole limpet hemocyanin conjugate for immunization. The isotype was immunoglobulin M(kappa). Specificity was determined by cell slide agglutination and enzyme-linked immunosorbent assay (ELISA). In both tests, the MAb reacted to serotypes D and A-D but not to serotypes A, B, and C. Furthermore, the specificity of the MAb determined by ELISA was the same as that of polyclonal antibody factor serum (PAb factor) 8, which showed high-level reactivity with serotypes D and A-D. These results supported the deduced specificity of the PAb-based antigenic factor 8. A total of 15 isolates of serotypes D and A-D but no serotype A isolates reacted with the MAb in cell slide agglutination tests. CRND-8 MAb can be used in place of PAb factor 8 for serotyping C. neoformans isolates and for the analysis of the antigen 8 epitope.

Serotypes of Cryptococcus neoformans isolated from patients prior to and during the AIDS era in Thailand

One hundred and eighty-seven strains of Cryptococcus neoformans isolated from patients in Thailand were characterized by biochemical varieties relating to serogroups. Canavanine-glycine-bromothymol blue (CGB) agar was used for differentiating the varieties of C. neoformans. Slide agglutination tests were performed with Crypto Check (Iatron, Inc., Tokyo) to determine their serotypes. Fifty-five percent (10 out of 18) of the pre-AIDS isolates were serotype B, 28% were serotype A, 5% were serotype D, and an unexpected 11% (2 out of 18) were serotype C. These are the first to be recorded in Asia. In contrast, among the 169 clinical isolates obtained between January 1993 and March 1995 (AIDS epidemic), serotype A was outstandingly predominant--93% (157 out of 169), serotype B was relatively low (3.6%) and both serotypes D and AD were 1.8%. The pattern of serotypes of the 59 isolates from known HIV-positive patients was closely similar to the total isolates during the AIDS epidemic. In determining the varieties of C. neoformans by CGB, only 1 of the 187 isolates gave a false reaction. On the basis of our findings, we believe that in the pre-AIDS era either C. neoformans var. gattii serotype B or serotype C were the common causative agents of cryptococcosis in Thailand. The advent of AIDS changed the pattern of serotypes with serotype A becoming predominant as has been reported world wide.

Electrophoretic karyotype and in vitro antifungal susceptibility of Cryptococcus neoformans isolates from AIDS patients

Electrophoretic karyotype (EK) was used to type 13 clinical isolates of Cryptococcus neoformans from eight AIDS patients. All of the isolates were also tested for their in vitro susceptibilities to fluconazole, itraconazole, D0870, flucytosine, and amphotericin B by a broth macrodilution technique performed according to the National Committee for Clinical Laboratory Standards recommendations. Although all strains were isolated from a limited geographic area, DNA typing showed a wide genetic variation in this group of patients, yielding seven different patterns. Two patients in whom C. neoformans was isolated in the same time period shared similar EK profiles, suggesting the possibility of cross-infection. In three patients, sequential isolates were evaluated: in two of them, EK analysis showed the persistence of the same genotype throughout the infection, whereas from the third, two isolates of C. neoformans with two different DNA profiles were obtained. Despite the small number of strains considered in this study, our susceptibility data indicate that C. neoformans isolates are very susceptible to the new triazoles.

Structure of the O-deacetylated glucuronoxylomannan from Cryptococcus neoformans serotype C as determined by 2D 1H NMR spectroscopy

The primary structure of the O-deacetylated capsular glucuronoxylomannan (GXM) isolated from Cryptococcus neoformans serotype C was investigated by 2D NMR spectroscopy. Assignment of the 1H NMR chemical shifts for the polysaccharide was accomplished from the analysis of DQF-COSY, TOCSY, NOESY and/or ROESY spectra of three isolates (298, 34, and 401). These isolates contain the same polysaccharide glycosyl residues but in different proportions. The serotype C GXM consists of two repeating polysaccharide units that have the following structures: [formula: see text] It is not known if these repeating units comprise a single or two separate polymer chains. The relative amounts of the more highly branched octasaccharide 1 in the isolates studied (i.e., approximately 75% in isolate 34, 50% in isolate 298, and 25% in isolate 401) can be used to explain the serological specificity of these isolates with C. neoformans factor sera, as was previously determined by ELISA in this laboratory. The octasaccharide 1 component is the one previously postulated as the structure of the serotype C GXM although definitive placement of the beta-Xyl-(1-->4) residues had previously not been determined. The heptasaccharide 2 component is uniformly found as the repeating unit in the polysaccharide from serotype B isolates. Additionally, GXM 401 was found to contain a small amount of the hexasaccharide repeating unit usually attributed to serotype A GXM.

Cryptococcosis in the era of AIDS--100 years after the discovery of Cryptococcus neoformans

Although Cryptococcus neoformans and cryptococcosis have existed for several millennia, a century has passed since the discovery of this encapsulated yeast and its devastating disease. With the advent of the AIDS pandemic, cryptococcal meningitis has emerged as a leading cause of infectious morbidity and mortality and a frequently life-threatening opportunistic mycosis among patients with AIDS. Both basic and clinical research have accelerated in the 1990s, and this review attempts to highlight some of these advances. The discussion covers recent findings, current concepts, controversies, and unresolved issues related to the ecology and genetics of C. neoformans; the surface structure of the yeast; and the mechanisms of host defense. Regarding cell-mediated immunity, CD4+ T cells are crucial for successful resistance, but CD8+ T cells may also participate significantly in the cytokine-mediated activation of anticryptococcal effector cells. In addition to cell-mediated immunity, monoclonal antibodies to the major capsular polysaccharide, the glucuronoxylomannan, offer some protection in murine models of cryptococcosis. Clinical concepts are presented that relate to the distinctive features of cryptococcosis in patients with AIDS and the diagnosis, treatment, and prevention of cryptococcosis in AIDS patients.

Comparison of multilocus enzyme electrophoresis and random amplified polymorphic DNA analysis for molecular subtyping of Cryptococcus neoformans. The Cryplococcal Disease Active Surveillance Group

We evaluated multilocus enzyme electrophoresis (MEE) and random amplified polymorphic DNA (RAPD) for their usefulness in subtyping 344 Cryptococcus neoformans clinical isolates obtained from four U.S. metropolitan areas in 1992 to 1994. MEE and RAPD with five primers both discriminated between the two varieties of C. neofromans. MEE divided C. neoformans var. neoformans isolates into 15 enzyme electrophoretic subtypes (ETs) arranged in three complexes. The predominant ET 1 complex contained 10 ETs, with isolates from 70% of patients in 1 ET. RAPD with five primers further sorted this predominant ET into 19 subtypes, with 60% of isolates sorting into three RAPD types. The ET 8 MEE complex, containing three ETs, could not be divided further by RAPD. The ET 7 complex (two ETs) included isolates from all serotype AD patients. Although both MEE and RAPD identified isolates of C. neoformans var. gattii, neither distinguished between serotypes B and C. These results showed that the two C. neoformans varieties could be identified by MEE or RAPD profile as well as by biochemical methods. RAPD improved the discriminatory power of MEE for isolates within the ET 1 complex but with other ETs offered little additional sensitivity over MEE and was less sensitive than MEE with isolates of C. neoformans var. gattii. This information will be useful in identifying particular environmental sources of disease-causing exposures, in seeking clusters of cases, and in determining whether an infecting strain changes over time.

Interference by hydroxyethyl starch used for vascular filling in latex agglutination test for cryptococcal antigen

The glucuronoxylomannan component of the Cryptococcus neoformans capsular polysaccharide confers serotype specificity, and its detection in cerebrospinal fluid or serum by the latex agglutination test is used for diagnosis. Low-molecular-weight hydroxyethyl starches can be used as an alternative to albumin for vascular filling. This study reports the occurrence of a false-positive result with the Pastorex Cryptococcus test (Sanofi Diagnostics Pasteur, Marnes la Coquette, France) for a patient receiving hydroxyethyl starch characterized by a substitution ratio of 0.6 (Elohes, Biosedra, Sèvres, France).

Primary cutaneous cryptococcosis and Cryptococcus neoformans serotype D

We report a healthy, 73-year-old Japanese woman who presented with primary cryptococcosis on the skin of both cheeks. She had initially developed an erythematous, partly ulcerated lesion on the right cheek 2 weeks earlier following an injury. There was no regional lymphadenopathy, and chest X-rays were normal. Histopathological findings showed granulomatous cell infiltration. Periodic acid Schiff staining revealed spores that were identified by the indirect immunoperoxidase staining method as Cryptococcus neoformans. The isolate was identified as C. neoformans var. neoformans serotype D. The skin lesions healed in 1 month without antifungal therapy. A literature review indicates that this serotype tends to produce cutaneous lesions without systemic involvement.

Determination of antigen binding specificities of Cryptococcus neoformans factor sera by enzyme-linked immunosorbent assay

The competitive binding specificities of glucuronoxylomannan (GXM) and its derivatives to factor sera of Cryptococcus neoformans were studied by enzyme-linked immunosorbent assay. An effort was made to determine the epitope specificity of each factor serum. Despite the presence of antigenic factor 1 on all serotypes of C. neoformans, variations in inhibition ability were observed with different GXMs. The panspecific component of factor serum 1 (antibody 1) appeared to be due to the presence of more than one antibody component. The activity was dependent on the 6-O-acetyl substituent. GXMs of serotypes A and D inhibited factor serum 2 equally well, indicating a low titer for the antibody 7 component. Serotype B GXM was a poor inhibitor, and serotype C GXM did not inhibit factor serum 2. The activity of factor serum 2 was 6-O-acetyl dependent. GXMs from typical serotype A and serotype D isolates were excellent inhibitors of factor serum 3. GXMs from serotype B were poorly inhibitory and serotype C did not inhibit factor serum 3. The activity of factor serum 3 was 6-O-acetyl dependent. The activity of factor serum 4 was due predominantly to antibody component 6. The activity of factor 4 was directed mainly against serotype C, and it was independent of 6-O-acetyl substitution Factor serum 5 was specific for serotype B GXMs. The inhibitory effect was independent of 6-O-acetyl substitution, but the effect was diminished by reduction of the glucuronic acid. The GXMs with a typical serotype C structure inhibited antibody 6. O deacetylation of the GXMs did not affect their inhibitory activity. However, reduction of glucuronic acid reduced factor serum 6 binding. Factor serum 8 was specific to serotype D; native GXMs of serotype A were slightly inhibitory. O deacetylation of the serotype D GXMs abrogated the inhibitory effect. O deacetylation alone abrogates the activity of antibody components 1, 2, 3, and 8. Reduction of glucuronic acid reduces the inhibitory activity of the GXM to antibody components 4, 5, and 6. Partial GXM structures and methyl glycosides did not effectively inhibit the activity of any of the factor sera.

Variation in the structure of glucuronoxylomannan in isolates from patients with recurrent cryptococcal meningitis

Capsular glucuronoxylomannans (GXM) of Cryptococcus neoformans var. neoformans isolates from patients with recurrent cryptococcal meningitis were analyzed by 1H nuclear magnetic resonance spectroscopy and for reactivity with factor sera (Iatron, Tokyo, Japan). For each patient the initial and relapse isolates had previously been shown to be indistinguishable by DNA restriction fragment length polymorphism analysis. For patients J11 and J22 the GXM of the initial and relapse isolates were identical. For patients SB4 and SB6 the GXM of the initial and relapse isolates differed in structure and reactivity with factor sera. In patient SB4 the initial isolate had a serotype A/D structure, and the first relapse isolate had a serotype A structure. The second relapse isolate was a mixture of structures composed of serotype D components, glucuronomannan (GM), and a minor serotype A component. Analysis of the initial isolate from patient SB6 showed a structure composed mainly of serotype D, GM, and minor serotype A components and components not assigned to a particular serotype (N). The relapse isolate had the same composition as the initial isolate except for an increase in the serotype A component. This increase in the serotype A component of the relapse isolate resulted in a change in the serological specificity from serotype D to serotype A/D. The initial isolate from patient J9 had serotype D and GM structures. The first two relapse isolates had serotype D, N, and GM structures and a minor serotype A component. The third relapse isolate had mainly a serotype D structure. All the J9 isolates reacted only with serotype D-specific factor serum. These results indicate that some isolates obtained from patients with recurrent C. neoformans infections have undergone a change in GXM structure during the course of infection. The modification of GXM structure observed in some relapse isolates is reflected in changed serological properties. The results may have important implications for the design of vaccines and antibody-based therapeutic strategies against C. neoformans.

Purification and characterization of the serotype-specific polysaccharide antigen of Trichosporon cutaneum serotype II: a disease-related antigen of Japanese summer-type hypersensitivity pneumonitis

Summer-type hypersensitivity pneumonitis (SHP) is a unique type of hypersensitivity pneumonitis and the most prevalent in Japan. Our previous study clarified that the causative agent of the disease is Trichosporon cutaneum, and that the patients with SHP have high titres of antibodies against the serotype-specific antigen of polysaccharide nature which exist in the high molecular weight fraction of the culture supernatant of the yeast. In this study, we purified the serotype-specific antigen of serotype II T. cutaneum by gel filtration and affinity chromatography using a monoclonal antibody, D-8, specific for a high molecular weight antigen of serotype II T. cutaneum, and elucidated the structure of the antigen. This affinity-purified antigen was shown to be an essentially acidic polysaccharide comprising mannose, xylose, and glucuronic acid (6:44:4.7). Chemical analysis showed that this polysaccharide antigen contains a (1-3)-linked mannan backbone attached with short side chains of (1-4)-linked mannose and a small proportion of (1-2)-linked xylose residues by substituting the 2- or 4-positions of the (1-3)-linked mannose residues of the main chain. Approximately one-fifth of the side chains were terminated with glucuronic acid residues. The antigenic epitope of the serotype-specific antigen was shown to involve the terminal glucoronic acid residues as revealed by immunodiffusion test and sandwich enzyme-linked immunosorbent assay using monoclonal antibody D-8.

Molecular and idiotypic analysis of antibodies to Cryptococcus neoformans glucuronoxylomannan

Antibodies to the Cryptococcus neoformans capsular glucuronoxylomannan (GXM) form the basis of two potential therapeutic intervention strategies, i.e., conjugate vaccines and passive antibody therapy. To better understand the molecular basis of the antibody response, the heavy- and light-chain immunoglobulin variable region (VH and VL, respectively) sequences of seven monoclonal antibodies (MAbs) to GXM were determined. Rabbit anti-idiotypic serum was made to the previously characterized murine MAb 2H1 and used to study MAb 2H1 idiotype expression in other GXM-binding MAbs and immune sera. MAb E1 originated from a C3H/HeJ mouse immunized with C. neoformans serotype A polysaccharide. MAbs 471, 1255, 339, 3C2, 386, and 302 originated from BALB/c mice immunized with polysaccharide of serotypes A, A, B, C, D, and D, respectively, conjugated to sheep erythrocytes. In the E1, VH uses V11 from the T15 gene family and JH3 and has a D segment of three amino acids, and the VL uses a VKSer-like gene family element and JK5. In MAbs 471 and 3C2, the VH uses VH7183-like gene family elements and JH2 and has D segments of seven amino acids, and the VL uses VK5.1 and JK1. In MAbs 1255 and 339, the VH uses VH10-like gene elements and JH4 and has six codon D segments, and the VL uses a VK21-like gene element and JK5. In MAbs 302 and 386, respectively, the VH uses VHGAM-like gene elements and JH2 and JH3 and has six and four codon D segments, and VL uses VK4/5-like gene elements and JK1.VH usage, MAb 2H1 idiotype expression, and fine specificity mapping define a minimum of three GXM epitopes which elicit protective antibodies. The results confirm that the antibody response is highly restricted, suggest a close relationship between molecular structure and serological properties, and provide insight into protein structural motifs important for GXM binding.

Restriction fragment length polymorphism analysis of Cryptococcus neoformans isolates from environmental (pigeon excreta) and clinical sources in New York City

Restriction fragment length polymorphism analysis of environmental (pigeon excreta) and clinical Cryptococcus neoformans var. neoformans isolates in a limited geographic area distinguished 6 strains among 8 environmental isolates and 12 strains among 17 clinical isolates. Clusters of patients with three strains types accounted for 47% of clinical isolates. Despite this diversity, two strains were shared by environmental and clinical isolates.

Polysaccharide antigens of the capsule of Cryptococcus neoformans

The major significance of the capsular polysaccharide of C. neoformans is its role in potentiating opportunistic infections by the yeast. It has the ability to exert a broad spectrum of influences on the immune response, from activation of phagocytic cells and complement components of the alternative pathway, to the induction of specific antibody, T-suppressor cells, DTH responses, and cytokines (51). These biological properties along with the serotype specificities are all determined by the physical properties and chemical structures of the polysaccharide antigens that compose the capsule. There is evidence not only for an association of lethal infections with serotype A in patients with advanced AIDS (34, 56), but also for a role for the capsule in directly influencing the infection of CD4+ cells by HIV (57). Together, these phenomena raise intriguing questions about the possible connection between the chemistry of these capsular antigens and cryptococcal infections in AIDS patients. One speculation is that AIDS creates the optimal physiological conditions for the establishment and spread of cryptococcosis. It has been observed that during the progression of AIDS there is a shift towards a T-2 response (14). This could lead to conditions that would inhibit the cellular immune responses that block dissemination of cryptococcal infections. Thus, an important consideration in the application of vaccine or immune modulation therapies in the treatment of cryptococcosis in AIDS victims would be the design of vaccines that could boost the T-1 immune response. It has been shown that the form and dose of an antigenic challenge can influence the induction of a T-1 or T-2 immune response (61). Recently, Murphy has reported that gamma interferon and interleukin 2 are up-regulated in the spleens of mice that produce anticryptococcal TDH and TAMP cells in response to immunogenic doses of cryptococcal culture filtrate antigen given with Freund's complete adjuvant (49). Perhaps purified cryptococcal antigens (e.g., MP) conjugated to an appropriate carrier or adjuvant could be used in therapeutic strategies to limit cryptococcosis in immunocompromised individuals. Future investigations of virulence and pathogenicity in the context of defined polysaccharide antigens from encapsulated strains of C. neoformans will contribute to a better understanding of the regulation of cryptococcal infection and immunity at the cellular and molecular levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Serotypes and mating types of clinical strains of Cryptococcus neoformans isolated in Taiwan

Twenty-one strains of Cryptococcus neoformans isolated from patients in Taiwan were characterized for serotypes and mating types. Slide agglutination test was performed with 8 factor-specific sera (Iatron Company, Japan) to determine the serotypes. Wheat bran agar (WBA) and malt extract agar (MEA, Wickerham) media were used for the mating tests. Twenty of the isolates were of serotype A, and one was serotype B. Except for 2 strains of serotype A, all of the serotype A strains mated with Filobasidiella neoformans var. neoformans, mating type a. The only serotype B strain mated with F. neoformans var. bacillispora mating type a in MEA medium. These data revealed the low prevalence (1/21; 4.8%) of C. neoformans var. gattii in Taiwan, a subtropically located isoland.

The 16S-like, 5.8S and 23S-like rRNAs of the two varieties of Cryptococcus neoformans: sequence, secondary structure, phylogenetic analysis and restriction fragment polymorphisms

The nucleotide sequences of the 16S-like, 5.8S and 23S-like rDNAs from the two varieties of Cryptococcus neoformans, C. neoformans var. neoformans and C. neoformans var. gattii, were determined. The rRNA locus has the typical eukaryote organization of 16S-5.8S-23S with the 16S-like and 5.8S rRNA genes separated by a 124-nucleotide spacer and the 5.8S and 23S-like rRNA genes separated by a 187-nucleotide spacer in each strain. The C. neoformans var. neoformans and C. neoformans var. gattii 16S-like, 5.8S and 23S-like rRNAs are, respectively 1802, 158, and 3358 nucleotides in length and share > 99% nucleotide sequence identity, a finding which strongly supports the present taxonomic classification of two varieties within a species. Comparative structure analysis was used to construct secondary-structure models for the deduced 16S-like and 5.8S-23S-like rRNA sequences, which are similar to those of other fungal rRNAs. The C. neoformans 16S-like and 23S-like rRNA sequences were aligned with other eukaryote sequences based on secondary and higher-order structures predicted by comparative structure analysis for phylogenetic analysis. There was good correspondence between the 16S-like and 23S-like derived phylogenetic trees. The closest known fungal relative is Trichosporon beigelii. Southern blot analysis revealed one C. neoformans strain with two types of DNA repeats coding for rRNA which differed in size by about 1000 bp. Restriction fragment length polymorphisms in the rDNA locus provide useful markers for the study of epidemiology and pathogenesis of C. neoformans infections.

Multilocus enzyme typing of Cryptococcus neoformans

Multilocus enzyme electrophoresis was adapted for subtyping Cryptococcus neoformans. The two cryptococcal varieties were clearly distinguishable. Isolates of the C. neoformans var. neoformans were sorted according to serotype and were sorted into four to five subtypes within each serotype. Nearly no two isolates of the C. neoformans var. gattii displayed the same enzyme electrophoretic type. This method may be a useful adjunct to current methods for classification and epidemiologic studies of cryptococci.

Characterization of a phenol oxidase from Cryptococcus neoformans var. neoformans

In Cryptococcus neoformans, enzymic oxidation of various catechols leads to melanin, a proposed virulence factor. A phenol oxidase enzyme of Cryptococcus neoformans var. neoformans produced at 25 C has been purified from an ultracentrifugal supernatant of an extract of broken cells. Hydrophobic interaction chromatography followed by anion-exchange column chromatography allowed purification of the phenol oxidase. The molecular weight of the enzyme estimated by gel filtration was about 80,000 and a dimeric species (Mw = 160,000) was suggested. The isoelectric point of the protein was approximately 4.1. An NH2-terminal 31 amino acid sequence was determined using phenol oxidase electroblotted onto a PVDF membrane after nondenaturing gel electrophoresis. Upon searching the Peptide Institute (Osaka) data base, no proteins with high degrees of homology were found.