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At least 73 records · Page 4Linked to original sources
PubMed1999

Truncated surface protective antigen (SpaA) of Erysipelothrix rhusiopathiae serotype 1a elicits protection against challenge with serotypes 1a and 2b in pigs.

Erysipelothrix rhusiopathiae is a causal agent of swine erysipelas, which is of economic importance in the swine industry by virtue of causing acute septicemia, chronic arthritis, and endocarditis. However, little is known about the genetic properties of its protective antigens. Recently, a surface protective antigen (SpaA) gene was identified from serotype 2 in a mouse model. We cloned spaA from virulent strain Fujisawa (serotype 1a) and determined that the N-terminal 342 amino acids without C-terminal repeats of 20 amino acids have the ability to elicit protection in mice. Fusions of 342 amino acids of Fujisawa SpaA and histidine hexamer (HisSpa1.0) protected pigs against challenge with both serotype 1 and serotype 2, the most important serotypes in the swine industry. Pigs immunized with HisSpa1.0 reacted well with both HisSpa1.0 and intact SpaA by enzyme-linked immunosorbent assay and immunoblotting. Serum collected at the time of challenge from a pig immunized with HisSpa1. 0 markedly enhanced the in vitro phagocytic and killing activity of pig neutrophils against the bacteria. DNA sequences of protective regions of spaA genes from five strains of serotypes 1 and 2 were almost identical. The full DNA sequences also seemed to be conserved among strains of all 12 serotype reference strains harboring the spaA gene by restriction fragment length polymorphism analysis of PCR products. These results indicates that SpaA is a common protective antigen of serotypes 1 and 2 of E. rhusiopathiae in swine and will be a useful tool for development of new types of vaccines and diagnostic tools for effective control of the disease.

Amino Acid Sequence↗
PubMed1995

Expression of Shigella dysenteriae serotype 1 O-antigenic polysaccharide by Shigella flexneri aroD vaccine candidates and different S. flexneri serotypes.

The potential utility of Shigella flexneri aroD vaccine candidates for the development of bi- or multivalent vaccines has been explored by the introduction of the genetic determinants rfp and rfb for heterologous O antigen polysaccharide from Shigella dysenteriae serotype 1. The serotype Y vaccine strain SFL124 expressed the heterologous antigen qualitatively and quantitatively well, qualitatively in the sense of the O antigen polysaccharide being correctly linked to the S. flexneri lipopolysaccharide R3 core oligosaccharide and quantitatively in the sense that typical yields were obtained, with ratios of homologous to heterologous O antigen being 4:1 for one construct and 1:1 for another. Moreover, both polysaccharide chains were shown to be linked to position O-4 of the subterminal D-glucose residue of the R3 core. In contrast to the hybrid serotype Y SFL124 derivatives, analogous derivatives of serotype 2a vaccine strain SFL1070 did not elaborate a complete heterologous O antigen. Such derivatives, and analogous derivatives of rough, O antigen-negative mutants of SFL1070, formed instead a hybrid lipopolysaccharide molecule consisting of the S. flexneri lipid A R3 core with a single repeat unit of the S. dysenteriae type 1 O antigen. Introduction of the determinants for the S. dysenteriae type 1 O antigen into a second serotype 2a strain and into strains representing other serotypes of S. flexneri, revealed the following for the expression of the heterologous O antigen: serotypes 1a, 1b, 2a, and 5a did not produce the heterologous O antigen, whereas serotypes 2b, 3a, 3b, 4a, 4b, 5b, and X did.

Bacterial Proteins↗
PubMed2003

Identification of Haemophilus influenzae serotypes by standard slide agglutination serotyping and PCR-based capsule typing.

To resolve discrepancies in slide agglutination serotyping (SAST) results from state health departments and the Centers for Disease Control and Prevention (CDC), we characterized 141 of 751 invasive Haemophilus influenzae isolates that were identified in the United States from January 1998 to December 1999 through an active, laboratory-based, surveillance program coordinated by the CDC. We found discrepancies between the results of SAST performed at state health departments and those of PCR capsule typing performed at the CDC for 56 (40%) of the isolates characterized: 54 isolates that were identified as a particular serotype by SAST were shown to be unencapsulated by PCR, and two isolates that were reported as serotypes b and f were found to be serotypes f and e, respectively, by PCR. The laboratory error most likely to affect the perceived efficacy of the conjugate H. influenzae type b (Hib) vaccine was the misidentification of isolates as serotype b: of 40 isolates identified as serotype b by SAST, 27 (68%) did not contain the correlating capsule type genes. The frequency of errors fell substantially when standardized reagents and routine quality control of SAST were used during a study involving three laboratories. An overall 94% agreement between SAST and PCR results showed that slide agglutination could be a valid and reliable method for serotyping H. influenzae if the test was performed correctly, in accordance with standardized and recommended procedures. An ongoing prospective analysis of all H. influenzae surveillance isolates associated with invasive disease in children less than 5 years old will provide more accurate national figures for the burden of invasive disease caused by Hib and other H. influenzae serotypes.

Agglutination↗
PubMed2003

Antimicrobial susceptibility and serotype distribution of Streptococcus pneumoniae and molecular characterization of multidrug-resistant serotype 19F, 6B, and 23F Pneumococci in northern Thailand.

Penicillin-resistant Streptococcus pneumoniae is widely spread worldwide. Our study was undertaken to examine the susceptibility and serotypes of S. pneumoniae in northern Thailand. Ninety-three S. pneumoniae strains were isolated from 93 patients at Chiang Mai University Hospital, Chiang Mai, Thailand, from September 1999 to June 2000. The strains were isolated from sputum (n = 51), blood (n = 15), nasopharynges (n = 14), and other sources (e.g., pus, ears, ascites, and cerebrospinal fluid) (n = 13). Of the 93 isolates, 29 (31.2%) were susceptible, 24 (25.8%) showed intermediate resistance (MIC, 0.12 to 1.0 micro g/ml), and 40 (43.0%) were fully resistant (MIC, >/=2.0 micro g/ml) to penicillin G. Seven (46.7%) from blood, 5 (35.7%) from nasopharynges, 15 (29.4%) from sputum, and 2 (15.4%) from other sources were susceptible isolates. Serotyping with the use of antiserum revealed differences in the predominant types that were susceptible (6A, 11A, and 19A), intermediately resistant (6B and 23F), and fully resistant (6B, 19F, and 23F). Molecular typing by pulsed-field gel electrophoresis of multidrug-resistant pneumococci showed four patterns (A, B, C, and D) for 16 isolates of serotype 19F, with pattern B being predominant (12 isolates). This finding was different from that with the Taiwan multidrug-resistant serotype 19F clone. Eleven isolates of serotype 6B all showed pattern E, and nine isolates of serotype 23F showed two patterns (F and G), with pattern F being predominant (seven isolates). This finding was similar to that with the Spanish multidrug-resistant serotype 23F clone. Our results indicated that the resistance of pneumococci to antibiotics in northern Thailand is progressing rapidly and that effort should be intensified to prevent any spread of pandemic multidrug-resistant serotypes 19F, 6B, and 23F.

Drug Resistance, Multiple, Bacterial↗
PubMed1997

A novel protein polymorphism differentiates the California serotype of infectious bronchitis from other serotypes common to California.

The California (Cal) serotype of infectious bronchitis virus (IBV) was isolated from layer flocks in southern California in the early 1980s. Since then, it has spread to the broiler-producing regions of central California, where it has been implicated in respiratory disease outbreaks in vaccinated flocks. Lack of a procedure for quickly identifying IBV serotypes in commercial chicken flocks has prevented the causal association of the IBV Cal serotype with respiratory disease outbreaks. A protein polymorphism has been identified in the matrix protein of the Cal serotype; it appears to be unique among other common serotypes of infectious bronchitis virus found in California. This polymorphism can be identified on western blots using raw or concentrated infectious allantoic fluid as the source material. Identification of the Cal serotype and of serotypes in the Mass and Conn groups can be performed rapidly using field samples from suspect flocks. The identification of this polymorphism provides an alternative method for the rapid identification of the Cal serotype of IBV.

Animals↗
PubMedDate not supplied

A restriction fragment length polymorphism-based polymerase chain reaction as an alternative to serotyping for identifying Salmonella serotypes.

The phase 1 (fliC) and phase 2 (fljB) Salmonella flagella genes were analyzed by restriction fragment length polymorphism (RFLP)-polymerase chain reaction (PCR) to aid in the identification of different Salmonella serotypes. Twenty-four phase 1 flagellin and eight phase 2 flagellin genes could be differentiated among each other with restriction endonucleases Sau3A and HhaI in RFLP-PCR analysis. These flagellin genes comprise the major antigenic formulas for 52 serotypes of Salmonella sp., which include the common serotypes found in poultry and other important food animal species. With the knowledge of the O antigen composition determined from conventional O serotyping, 90% of the Salmonella serotypes could be identified by this double restriction enzyme RFLP analysis of fliC and fljB genes. This RFLP-PCR flagellar typing scheme was successfully applied to the identification of serotype for 112 Salmonella isolates obtained from poultry environment. There was a significant correlation between RFLP-PCR and conventional serotyping (chi-square, P < 0.001). Overall, PCR-RFLP proved to be a fast, accurate, and economical alternative approach to serotyping Salmonella sp.

Animals↗
PubMedDate not supplied

New serotype 2 and attenuated serotype 1 Marek's disease vaccine viruses: comparative efficacy.

Attempts were made, through selection of optimum viral strains, to develop improved vaccines against Marek's disease (MD). Seven attenuated serotype 1 strains and 22 avirulent serotype 2 strains, both alone and in combination with the FC126 strain of serotype 3, were screened for protective efficacy against challenge with virulent and very virulent MD viral strains. The three viruses selected as most promising were evaluated alone and in various combinations and compared with commercially available vaccines, including FC126, bivalent (FC126 + SB-1), and CV1988/C, in 12 separate assays. Two of these new viruses--301B/1 (serotype 2) and Md11/75C/R2 (serotype 1)--were exceptionally protective compared with prototype vaccine strains. Four new monovalent and polyvalent vaccines based on these two isolates protected chickens better than FC126 alone or CV1988/C alone. Three of these new vaccines provided better protection than the bivalent (FC126 + SB-1) vaccine. Protective synergism was noted commonly between viruses of serotypes 2 and 3 but only sporadically between serotypes 1 and 2 or between serotypes 1 and 3. Strain CVI988/C was protective but was no better than FC126 alone, and it was less effective than bivalent (FC126 + SB-1) vaccine, even when used as a bivalent vaccine with FC126 or SB-1.

Animals↗
PubMed1998

Purification and characterization of a protease from Actinobacillus pleuropneumoniae serotype 1, an antigen common to all the serotypes.

A high molecular-mass proteolytic enzyme of Actinobacillus pleuropneumoniae serotype 1, was purified from culture supernatants (CSN) by using DEAE-cellulose and sepharose-4B-gelatin chromatography. In 10% SDS-polyacrylamide gels copolymerized with porcine gelatin, the protease showed a single band of activity of > 200 kDa. However, minor molecular-mass proteolytic bands were observed when the protease was electrophoresed in the presence of either 5% beta-mercaptoethanol, 50 mM dithiothreitol, or 0.25 M urea. Furthermore, when the > 200-kDa purified protein was passed through a sucrose gradient, several bands with proteolytic activity were found: 62, 90, 190, and 540 kDa. The proteolytic activity was increased in the presence of calcium or zinc and was not affected after being heated at 90 degrees C for 5 min. Proteolytic activities were also observed in CSN from all A. pleuropneumoniae serotypes and biotypes. The purified protease hydrolyzed porcine IgA and IgG in vitro. In addition, by immunoblot the protease was recognized by serum of naturally infected pigs with serotypes 1 and 5, and by serum of pigs experimentally infected with serotypes 1, 2, 8, or 9. Serum of a pig vaccinated with CSN of a serotype 3 strain also recognized the protease, but not sera of pigs vaccinated with a bacterin (serotype 1). Proteins from CSN of all the serotypes, which were precipitated with 70% (NH4)2SO4, were recognized by a polyclonal antibody raised against the purified protease. Taken together these results indicate that an antigenic protease is produced in vivo by all the serotypes of A. pleuropneumoniae. The results indicate that proteases could have a role in the disease and in the immune response of pigs infected with A. pleuropneumoniae.

Actinobacillus pleuropneumoniae↗
PubMed2003

Competitive exclusion of Yersinia enterocolitica biotype 4, serotype O:3 by Yersinia enterocolitica biotype 1A, serotype O:6,30 in tissue culture and in pigs.

AIMS: To study the adhesion properties of a biotype 4, serotype O:3 (human pathogenic) strain of Yersinia enterocolitica and to determine if adhesion in vitro and colonisation in vivo can be prevented by competition with a biotype 1A, serotype O:6,30 (non-pathogenic) strain. To study interaction between Y. enterocolitica biotype 4, serotype O:3 and cultured epithelial cells using the synthetic tripeptide arginine-glycine-aspartic acid (RGD). METHODS: The human intestinal epithelial (HEp-2) cell line was used for in vitro studies. Inocula of Y. enterocolitica biotype 4, serotype O:3 radiolabelled using tritium were incubated with HEp-2 cells and RGD tripeptide, or with Y. enterocolitica biotype 1A, serotype O:6,30 sequentially or concurrently, then washed and lysed, and radioactivity measured to determine the effect of RGD on adhesion, and competitive exclusion of pathogenic by non-pathogenic bacteria. For in vivo studies, two groups of 5-week-old piglets (n=5/group) were sequentially inoculated orally with 5 x 10(9) colony forming units (cfu) of either a non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica followed by a pathogenic biotype 4, serotype O:3 strain, or vice versa. Pigs were monitored for carriage of strains using bacterial culture and a multiplex polymerase chain reaction (PCR). RESULTS: The RGD tripeptide significantly inhibited adherence of the pathogenic Y. enterocolitica strain to cultured epithelial cells, suggesting that adhesion involved the RGD tripeptide sequence. The non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica prevented adhesion of the pathogenic strain to cells in vitro when allowed to adhere first. Pathogenic Y. enterocolitica was consistently isolated from rectal swabs from 80-100% of pigs on all sampling occasions but not from oral swabs after 14 days in pigs first inoculated with the non-pathogenic strain or at 26 days in pigs first inoculated with the pathogenic strain. CONCLUSIONS: A non-pathogenic strain of Y. enterocolitica reduced adhesion of a human pathogenic strain in vitro but not in vivo.

Journal Article↗
PubMed1985

Sequence of the serotype-specific glycoprotein of the human rotavirus Wa strain and comparison with other human rotavirus serotypes.

Complementary DNA was synthesized from the double-stranded RNA of the Wa strain of human rotavirus and inserted into the bacterial plasmid pBR322. Clones which contained the gene that codes for the viral glycoprotein (VP7) were identified and the nucleotide sequence was determined. The gene was 1062 base pairs in length with an open reading frame which coded for 326 amino acids. Two potential glycosylation sites were found as well as two hydrophobic regions at the N-terminus of the polypeptide. The untranslated regions at the 5' and 3' ends were 48 base pairs and 33 base pairs long, respectively. Only one nucleotide at position 493 differed from the sequence of the Wa VP7 gene described by Richardson et al. (1984, J. Virol. 51, 860-862). A strong prokaryotic promoter sequence was also found between residues 434 and 462. A comparison of the amino acid sequence of the Wa strain (serotype 1) to the Hu/5 strain of human rotavirus (serotype 2) and SA11, the simian rotavirus (serotype 3), revealed a high degree of homology (79.1% and 83.1%, respectively) between the serotypes, suggesting that rotavirus serotypes are stable. The hydrophilic regions of VP7 of the three serotypes were identified and compared for homology. Four of these regions showed variation between serotypes.

Amino Acid Sequence↗
PubMed2001

Development of a fluorogenic RT-PCR system for quantitative identification of dengue virus serotypes 1-4 using conserved and serotype-specific 3' noncoding sequences.

A fluorogenic reverse transcriptase-polymerase chain reaction (RT-PCR) system was developed for use as a rapid diagnostic test for determining dengue viremia. The dengue virus 3'-noncoding sequence was utilized to formulate serotype-specific RT-PCR assays for quantitative identification of the four different dengue virus serotypes. A generic RT primer set containing two dengue specific anti-sense primers (DV-L1 and DV-L2) could be used to transcribe extracted viral RNA of all four dengue virus types to complimentary DNA (cDNA). The resultant dengue viral cDNA could be quantitatively identified at the serotype level by the 5'-3' exonuclease assay using four serotype-specific sense primers. The fluorogenic dengue type-specific RT-PCR can detect each of the four dengue types at similar low detection limits, i.e. 20-50 plaque forming units per milliliter of serum. Two panels with four dengue reference serotypes and 134 clinical samples were used to validate detection sensitivity and specificity of the dengue serotype RT-PCR assay, using virus isolation in cell culture as the criterion standard. By analyzing sera samples from Puerto Rico that were collected from 1999 through 2000, the assay demonstrated high level detection sensitivity and specificity of 92.8 and 92.4%, respectively, for all four dengue virus serotypes.

3' Untranslated Regions↗
PubMed2003

Conversion of Shigella flexneri serotype 2a to serotype Y in a shigellosis patient due to a single amino acid substitution in the protein product of the bacterial glucosyltransferase gtrII gene.

Conversion of serotype from 2a to Y was demonstrated with five Shigella flexneri isolates recovered from an infected patient. When introduced into the serotype Y isolate, the glucosyltransferase (gtr) II gene of the serotype 2a isolate is capable of inducing the conversion from serotype Y to 2a. In contrast, the gtrII of the serotype Y isolate lacks the capacity to change serotype, resulting from a Cys-->Tyr substitution in its predicted protein sequence. The protein product of the gtrII gene was detected. This is the first report of serotype conversion of S. flexneri in humans, and successful detection of the protein product from a gtr gene.

Amino Acid Substitution↗
PubMed2006

Serotypes of Streptococcus pneumoniae isolated from blood and cerebrospinal fluid related to vaccine serotypes and to clinical characteristics.

Pneumococci isolated from blood and cerebrospinal fluid from 1998 to 2001 in 2 counties in south-west Sweden were serotyped with the capsular reaction test. Of the 836 strains, 353 (42%), 598 (72%) and 789 (94%) belonged to serotypes included in the 7- and 11-valent pneumococcal conjugate vaccines and in the 23-valent polysaccharide vaccine, respectively. The most common serotype was type 1 (119 isolates) followed in descending frequency by serotypes 7F, 9V, 14, 4 and 12F (90-49 isolates per serotype). The coverage rates of the 7- and 11-valent conjugate vaccines among 58 strains isolated from children and adolescents 0-19 y of age were 46% and 93%, respectively. A comparison of clinical characteristics of infections caused by different serotypes showed that types 1 and 7F were less commonly associated with severe underlying diseases, that patients infected with these serotypes were younger than the average and, thus, had a lower case-fatality rate.

Adolescent↗
PubMed2004

Four antibiotic-resistant Streptococcus pneumoniae clones unrelated to the pneumococcal conjugate vaccine serotypes, including 2 new serotypes, causing acute otitis media in southern Israel.

This study examined the prevalence of antibiotic-resistant clones that belong to serotypes not included in the pneumococcal conjugate vaccines and that cause a significant percentage of acute otitis media (AOM) in children in southern Israel. During 1998-2001, 2467 pneumococcal isolates, obtained from middle-ear fluid of children <3 years old with AOM, were characterized by antimicrobial susceptibility testing, serotype testing, and pulsed-field gel electrophoresis. Non-vaccine type (NVT) strains constituted 477 (19%) of the 2467 isolates, of which 173 (36%) belonged to only 4 serotypes: 35B, 33F, 21, and 15B/C. For serotype 35B, 47 (96%) of 49 strains were penicillin nonsusceptible, and 93% constituted a single clone; for serotype 33F, 31 (82%) of 38 strains were penicillin nonsusceptible, and 95% constituted a single clone; for serotype 21, 38 (93%) of 41 strains were penicillin nonsusceptible, and 93% constituted a single clone; for serotype 15B/C, 22 (49%) of 45 strains were penicillin nonsusceptible, and 42% constituted a single clone. Two of these clones have not been described elsewhere. The high prevalence of NVT clones should increase the awareness of the potential for replacement of the vaccine strains with these NVT antibiotic-resistant strains.

Acute Disease↗
PubMed1988

Adenoviruses from patients with AIDS: a plethora of serotypes and a description of five new serotypes of subgenus D (types 43-47).

We analyzed 67 adenovirus isolates from 48 patients with AIDS. The isolates included 5 of subgenus A (all Ad31), 23 of subgenus B, 4 of subgenus C (all Ad5), and 35 of subgenus D. The subgenus A and C strains were from liver, lung, blood, urine, and stool and were unremarkable in their antigenic characteristics. The subgenus B strains were mostly from urine and were serotyped by neutralization (SN) and hemagglutination-inhibition (HAI) tests as Ad11 (12 isolates), Ad16 (1), Ad35 (3), and Ad21/H21 + 35 (1) plus new intermediate strains 34/H11 (3), 35/H11 (1), and 11 + 35/H11 (2). The subgenus D serotypes from 24 patients were mostly from stool specimens and consisted of 8 isolates of known serotypes, 16 of antigenically intermediate strains, and 11 of five new adenovirus types with distinct antigenic and restriction enzyme characteristics. The new serotypes were described as candidate types 43-47 in accordance with currently accepted taxonomic criteria. Ad45, 46, and 47 showed a major relation by HAI with Ad29, 24, and 20, respectively. Four intermediate types were related to the new serotypes. The plethora of serotypes from patients with AIDS suggests that no epidemiological significance can be attached to any one serotype.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Actinomyces georgiae sp. nov., Actinomyces gerencseriae sp. nov., designation of two genospecies of Actinomyces naeslundii, and inclusion of A. naeslundii serotypes II and III and Actinomyces viscosus serotype II in A. naeslundii genospecies 2.

DNAs of type strains and representative members of Actinomyces groups from the human periodontal flora and from other habitats were compared by using the S1 nuclease procedure to determine their genetic relatedness. One rather common group from the human periodontal flora, previously called "Actinomyces D08," is phenotypically distinct from, and genetically unrelated to, previously described species. We propose the name of Actinomyces georgiae for this organism; the type strain is strain ATCC 49285. Another common group from the human periodontal flora is Actinomyces israelii serotype II, which was found genetically distinct from the type strain of A. israelii (serotype I) and from other previously described species of Actinomyces. We propose the name Actinomyces gerencseriae for this organism; the type strain is strain ATCC 23860. A. naeslundii serotype I strains were distinct from the other strains studied. A separate genospecies which included strains of A. naeslundii serotypes II and III and A. viscosus serotype II was delineated. Strains of Actinomyces serotype WVA 963 constitute an additional distinct genospecies. Because there are no reliable phenotypic tests, other than serological analyses, to differentiate Actinomyces serotype WVA 963 and the two genospecies of A. naeslundii, no taxonomic changes are proposed for these three genospecies.

Actinomyces↗
PubMed2006

Comparison of secular trends in pneumococcal serotypes causing invasive disease in Denver, Colorado (1971-2004) and serotype coverage by marketed pneumococcal vaccines.

Invasive pneumococcal isolates from three hospitals in Denver, CO, USA were serotyped between 1971 and 2004. Serotype 14 was most common (13.2%), and other prevalent serotypes (3, 4, 6, 9 and 19) together accounted for 44.1% of the isolates. All prevalent serotypes and 91.3% of the total isolates were covered by pneumococcal polysaccharide vaccine, while 79.1% of prevalent serotypes and 56.7% of total isolates were covered by pneumococcal conjugate vaccine. Serotypes 6, 9 and 14 were more common in the final decade than in the first decade studied (37.3% vs. 20.2%), whereas serotypes 3 and 23 were more common in the first decade (18.5% vs. 11.0%).

Colorado↗
PubMed1998

The different binding patterns of two immunoglobulin M monoclonal antibodies to Cryptococcus neoformans serotype A and D strains correlate with serotype classification and differences in functional assays.

Cryptococcus neoformans var. neoformans strains have historically been divided into serotypes A and D on the basis of reactivity with rabbit sera. Previously, we noted that two murine immunoglobulin M monoclonal antibodies (MAbs) to the capsular glucuronoxylomannan produced different indirect immunofluorescence (IF) patterns, described as annular and punctate, when bound to C. neoformans cells from different strains. In this study, we examined the reactivity of these two MAbs, known as 12A1 and 13F1, with 20 C. neoformans var. neoformans strains, of which 13 were serotype A and 7 were serotype D. For all strains, MAb binding was studied by IF and agglutination assays. In addition, we blindly tested the IF patterns of 22 C. neoformans var. neoformans strains. For selected strains, MAb binding was studied by flow cytometry (FACScan) and phagocytosis assays. The epitopes recognized by MAbs 12A1 and 13F1 were found in all of the strains. MAb 12A1 binding produced an annular IF pattern with all of the strains, irrespective of the serotype classification. MAb 13F1 binding produced annular binding with all of the serotype A strains and punctate binding with 19 of 20 serotype D strains. In general, the punctate IF pattern was associated with lower fluorescence intensity, a requirement for higher antibody concentrations to produce yeast cell agglutination, and lower opsonic efficacy. Our results provide strong support for the existing classification of two serological types for strains assigned to variety neoformans and indicate qualitative and quantitative antigenic differences among serotype A and D strains.

Animals↗