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[Serotyping of 48 isolates of Candida albicans: predominance of serotype A over B in Venezuela].

The study of serotyping of isolates of Candida albicans of clinical material obtained from different geographic areas of Venezuela suggest that serotype A is predominant over type B. These results are in relation with results obtained in other countries. Type A serotype is predominant in 57 to 100% in the areas studied. Only in 2 cities serotype B was isolated. Both serotypes of Candida albicans were observed in intertriginous, mucosal, inguinal and lung forms. These studies have allowed us to have information about the predominance of serotypes in certain areas of the country.

Agglutination Tests↗

Detection of antibodies against Actinobacillus pleuropneumoniae, serotype 2 in porcine colostrum using a blocking enzyme-linked immunosorbent assay specific for serotype 2.

A blocking enzyme-linked immunosorbent assay (ELISA) developed for detection of antibodies to Actinobacillus pleuropneumoniae serotype 2 in sera from pigs (Nielsen et al., 1991) was evaluated for its suitability to detect antibodies in colostrum to this serotype. Using colostrum from sows experimentally infected with serotype 2 and from herds known to be infected with this serotype, the sensitivity of the test was 100%. Antibodies to A. pleuropneumoniae serotype 2 could be detected in colostrum of experimentally infected sows until at least 5 days after farrowing. Positive results were not observed with colostrum samples from herds known to be free from A. pleuropneumoniae. The high diagnostic sensitivity and specificity of the assay indicated that screening of herds for A. pleuropneumoniae serotype 2 infection by testing colostrum would be a reliable and simple method for herd monitoring.

Actinobacillus pleuropneumoniae↗

Differences in the carriage and the ability to utilize the serotype associated virulence plasmid in strains of Salmonella enterica serotype Typhimurium investigated by use of a self-transferable virulence plasmid, pOG669.

Most strains of Salmonella enterica subspecies enterica serotype typhimurium (S. typhimurium) naturally harbour a virulence plasmid which carries the salmonella plasmid virulence (spv) genes. However, isolates belonging to certain phage types are generally found without the plasmid. We have utilized a self-transferable virulence plasmid, pOG669 to investigate the effect of introduction of spv genes into strains of such phage types. The use of the co-integrate plasmid, pOG669, was validated on a diverse collection of strains. pOG669 was transferred into strains of serotypes that are normally associated with the possession of virulence plasmids. All strains maintained the wild type level of virulence in a mouse model, except that introduction of pOG669 restored normal virulence levels in an avirulent, plasmid free strain of S. dublin and resulted in a decrease in virulence in a strain of S. dublin from clonal line Du3. S. gallinarum did not become virulent in mice, but pOG669 was functionally interchangeable with the wild type plasmid when strains were tested in a chicken model. Strains of serotypes not normally associated with the carriage of a virulence plasmid did not increase in virulence upon the introduction of pOG669. An IncX plasmid pOG670 that was included as control was incompatible with the virulence plasmid in a strain of S. dublin, demonstrating that the common virulence plasmid of this serotype is of a different incompatibility group than other virulence plasmids. Strains of S. typhimurium from phage types that do not normally carry a virulence plasmid responded differently to attempts to introduce pOG669. No transconjugants were observed with the strains of DT5 and DT21. The introduction of pOG669 did not alter the virulence of JEO3942(DT10), DT35 and JEO3949(DT66) significantly, while DT1 and DT27 became more virulent. DT27 became as virulent as wild type C5, while logVC(10) of DT1 only increased from 4.1 to 5.7. The ability to express spv-genes was measured by use of an spvRAB'-cat fusion. Expression in S. enteritidis was found to be higher than in other serotypes tested. Only serotypes that naturally carry a virulence plasmid expressed spv-genes. The strain of DT1 expressed spv at a very low level, while expression in the strains of DT10 and DT35 was approximately 2-fold lower than in a control strain of S. typhimurium, while the level in the DT66 strain corresponded to the control strain. The plasmid pSTF9, which carried the fusion gene could not be introduced into the strains of DT5, DT21 and DT27. The RpoS level in the strains was measured indirectly by use of a katE-lacZ fusion. In the DT5 strain the level of expression was low, while the strains JEO3942(DT10), DT21, DT27 and DT35 expressed 4-5 fold the level in this strain. An internal fragment of the rpoS gene was sequenced in three strains. These all showed an identical sequence to a published S. typhimurium rpoS gene.

Animals↗

Purification and characterization of serotype 6 fimbriae from Bordetella pertussis and comparison of their properties with serotype 2 fimbriae.

Fimbriae were removed from Bordetella pertussis (serotype 1.3.6) by mechanical shearing and purified by precipitation with ammonium sulfate, pH-dependent precipitation at pH 7.4, followed by two successive extractions of the precipitated fimbriae with 4 M urea. By electron microscopy, the precipitated fimbriae appeared as aggregated bundles of long, relatively straight filaments which were disaggregated to individual flexuous filaments at pH 10.5. These purified fimbriae were identified as serotype 6 agglutinogens, since antibody to the purified fimbriae agglutinated B. pertussis strains serotyped as 1.3.6, 1.2.3.6, or 1.2.3.4.6 but did not agglutinate strains of serotype 1.2.3.4, 1.2.3, or 1.3. In contrast, antibody to serotype 2 fimbriae only agglutinated B. pertussis strains containing serotype 2 agglutinogen. Purified type 6 and 2 fimbriae were found to be weakly cross-reactive by enzyme-linked immunosorbent assay, using polyclonal antibody to each type of fimbria. In an immunoblot assay, polyclonal antibodies to a 22,000-dalton subunit of fimbriae from B. bronchiseptica reacted strongly with the type 2 fimbrial subunit of B. pertussis, but only weakly with the type 6 subunit. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein subunit of the type 6 fimbriae migrated with a molecular weight of 21,500, whereas the type 2 fimbrial subunit had a molecular weight of 22,000. The two types of subunits had similar amino acid compositions and showed amino-terminal sequence homology in 15 of 21 amino acids. The amino-terminal amino acid sequences of the B. pertussis fimbriae were distinct from those reported for fimbriae from other gram-negative bacteria. Neither the type 6 nor the type 2 fimbriae caused hemagglutination when assayed with several types of erythrocytes.

Amino Acid Sequence↗

Serotype 1-specific monoclonal antibody-based antigen capture immunoassay for detection of circulating nonstructural protein NS1: Implications for early diagnosis and serotyping of dengue virus infections.

Rapid diagnosis and serotyping of dengue virus (DV) infections are important for timely clinical management and epidemiological control in areas where multiple flaviviruses are endemic. However, the speed and accuracy of diagnosis must be balanced against test cost and availability, especially in developing countries. We developed a specific antigen capture enzyme-linked immunosorbent assay (ELISA) for early detection and serotyping of DV serotype 1 (DV1) by using well-characterized monoclonal antibodies (MAbs) specific to nonstructural protein 1 (NS1) of DV1. With this assay, a total of 462 serum specimens from clinically probable DV1-infected patients during the DV1 epidemic in Guangdong, China, in 2002 and 2003 were analyzed. DV1 NS1 was detectable in blood circulation from the first day up to day 18 after onset of symptoms, with a peak at days 6 to 10. The sensitivity of DV1 NS1 detection in serum specimens with reference to results from reverse transcriptase PCR was 82%, and the specificity was 98.9% with reference to 469 healthy blood donors. No cross-reactions with any of the other three DV serotypes or other closely related members of the genus Flavivirus (Japanese encephalitis virus and Yellow fever virus) were observed when tested with the clinical specimens or virus cultures. These findings suggest that the serotype-specific MAb-based NS1 antigen capture ELISA may be a valuable tool for early diagnosis and serotyping of DV infections, while also providing a standardized assay for the analysis of a great number of clinical samples with convenience and cost-effectiveness.

Antibodies, Monoclonal↗

Pathological changes in calves injected intradermally with Mycobacterium intracellulare serotype Davis and M. avium serotype 2.

Three strains of the M. intracellulare-M. avium complex were injected intradermally into 12 calves. M. intracellulare serotype Davis (M. avium complex serotype 8) was injected into five calves. One calf died with disseminated caseous granulomas at 79 days; three calves killed between 56 and 82 days after inoculation had widely disseminated caseous or caseous or caseocalcareous granulomas. One calf killed at 173 days had only encapsulated granulomas at the injection site and its regional lymph node. Two strains of M. avium serotype 2 (M. avium complex serotype 2) were injected intradermally into seven calves. Six had disseminated granulomas when killed 54-170 days after inoculation. One calf killed at 55 days had granulomas confined to the inoculation sites and their regional lymph nodes. Lesions induced by both M. avium serotype 2 and M. intracellulare serotype Davis were initially caseocalcareous granulomas which became encapsulated and nonprogressive after about 112 days. Two calves inoculated with similar doses of M. bovis and killed in extremis at 37 and 65 days after inoculation had disseminated progressive lesions without encapsulation.

Animals↗

Construction of four double gene substitution human x bovine rotavirus reassortant vaccine candidates: each bears two outer capsid human rotavirus genes, one encoding P serotype 1A and the other encoding G serotype 1, 2, 3, or 4 specificity.

Previously, four human x bovine rotavirus reassortant candidate vaccines, each of which derived ten genes from bovine rotavirus UK strain and only the outer capsid protein VP7-gene from human rotavirus strain D (G serotype 1), DS-1 (G serotype 2), P (G serotype 3), or ST3 (G serotype 4), were developed [Midthun et al., (1985): Journal of Virology 53:949-954; (1986): Journal of Clinical Microbiology 24:822-826]. Such human x bovine reassortant vaccines should theoretically provide antigenic coverage for the four epidemiologically most important VP7(G) serotypes 1, 2, 3, and 4. In an attempt to increase the antigenicity of VP7-based human x animal reassortant rotavirus vaccines which derive a single VP7-encoding gene from the human strain and the remaining ten genes from the animal strain, we generated double gene substitution reassortants. This was done by incorporating another protective antigen (VP4) of an epidemiologically important human rotavirus by crossing human rotavirus Wa strain (P serotype 1A), with each of the human x bovine single VP7-gene substitution rotavirus reassortants. In this way four separate double gene substitution rotavirus reassortants were generated. Each of these reassortants bears the VP4-encoding gene from human rotavirus Wa strain, the VP7-encoding gene from human rotavirus strain D, DS-1, P, or ST3, and the remaining nine genes from bovine rotavirus strain UK. The safety, antigenicity, and protective efficacy of individual components as well as combinations of strains are currently under evaluation.

Animals↗

The use of an enzyme-linked immunosorbent assay to detect IgG antibodies to serotype-specific and group-specific antigens of fowl adenovirus serotypes 2, 3 and 4.

A sensitive enzyme-linked immunosorbent assay (ELISA) has been developed which can detect serotype and group-specific antibodies (IgG) to fowl adenovirus serotypes 2, 3 and 4. The chickens produced principally type-specific antibodies after a single oral inoculation of virus which enabled that strain to be identified by the ELISA. However, inoculation of an heterologous serotype, although inducing strain-specific antibodies to itself, also induced high levels of antibody to the group-specific antigens. This masked the serotype-specific antibodies in the ELISA to the first serotype. The ELISA, which has similar sensitivity to the serum neutralisation test, could be used as a rapid, easily performed test to identify fowl adenovirus-specific antibodies.

Adenoviridae↗

The Shigella flexneri serotype Y vaccine candidate SFL124 originated from a serotype 2a background.

Shigella flexneri is endemic in most developing countries and responsible for the highest mortality rate among the Shigella species. The attenuated serotype Y S. flexneri strain SFL124 has been used as the parental strain for the development of recombinant vaccines expressing multiple O-antigen structures. During the development of one such multivalent vaccine, a region of gtrII homology was found in SFL124. Sequencing and analysis of this region revealed the presence of an insertion element interrupted serotype 2a serotype-conversion locus in the serotype Y vaccine strain SFL124. The data presented suggests that SFL124 has derived from a serotype 2a background.

Base Sequence↗

Molecular characterisation of pneumococcal serotype 16F: Established predominant carriage and otitis media serotype in the 7vPCV era.

Young Australian Aboriginal children in remote communities experience very high rates of pneumococcal carriage and otitis media. Prior to introduction of the 7-valent pneumococcal conjugate vaccine (7vPCV, Prevenar), serotype 16F was an important type found in nasal and ear discharge swabs. Since commencement of pneumococcal immunisation for Aboriginal infants in 2001, 16F has become the predominant established serotype in carriage and otitis media in young Aboriginal children. BOX typing and multi-locus sequence typing revealed a diverse population of serotype 16F strains, and evidence of potential capsule switching from a vaccine serotype 4 to a serotype 16F.

Australia↗

A comparison of salmonella serotypes found in the faeces of gulls feeding at a sewage works with serotypes present in the sewage.

The numbers of salmonella serotypes in raw sewage, sewage sludge and final effluent at a sewage treatment works were determined. Resting gulls which had previously been feeding on the sewage were disturbed and individual faecal samples tested for the presence of salmonellae. The serotypes were compared with those in the sewage. Six serotypes were isolated from the sewage, Salmonella stanley being found in all types of samples. Eleven of the twenty gull faeces samples were positive for salmonellae, a carriage rate of 55%. Seven serotypes were found, S. stanley being most frequent. Three serotypes were found in both sewage and gull faeces.

Animals↗

Serotype antigens of Neisseria meningitidis and a proposed scheme for designation of serotypes.

Neisseria meningitidis serogroups B and C were originally subdivided into serotypes by the use of two different classification systems based upon type-specific bactericidal antibodies and immunoprecipitation in agar gels, respectively. The serotype specificities were later found to be associated with different major outer membrane proteins and with the lipopolysaccharide. Physiochemical characterization of the four to five major outer membrane proteins has resulted in designation of classes 1-5 on the basis of peptide mapping. The class 2 (41,000-dalton) or class 3 (38,000-dalton) protein is present in all meningococcal strains. They both are predominant proteins, show a useful degree of antigenic variation, and are epidemiologically relevant. A new serotyping nomenclature and scheme based on these two proteins and the lipopolysaccharide is therefore proposed. With use of this scheme, a meningococcal strain could be identified by serogroup to protein-serotype to lipopolysaccharide serotype, as in B:2a:L3. The class 1 (46,000-dalton) protein can be used to further define a meningococcal strain, as in B:2a:P1.2:L3.

Antibodies, Bacterial↗

Direct serotyping of human rotavirus in stools by an enzyme-linked immunosorbent assay using serotype 1-, 2-, 3-, and 4-specific monoclonal antibodies to VP7.

Four serotypes of human rotaviruses that can be differentiated by neutralization tests have been described so far. We prepared serotype 1-, 2-, 3-, and 4-specific, neutralizing monoclonal antibodies to human rotaviruses. All were directed to VP7, a glycoprotein that carries a major serotype specificity. An enzyme-linked immunosorbent assay using these monoclonal antibodies has been developed for serotyping human rotavirus isolates. The sensitivity and specificity of this method were verified by using various strains of human rotavirus that were adapted to cell culture. Furthermore, it was shown that the method was applicable to serotyping human rotaviruses directly in stool specimens.

Antibodies, Monoclonal↗

Identification and differentiation of the nine African horse sickness virus serotypes by RT-PCR amplification of the serotype-specific genome segment 2.

This paper describes the first RT-PCR for discrimination of the nine African horse sickness virus (AHSV) serotypes. Nine pairs of primers were designed, each being specific for one AHSV serotype. The RT-PCR was sensitive and specific, providing serotyping within 24 h. Perfect agreement was recorded between the RT-PCR and virus neutralization for a coded panel of 56 AHSV reference strains and field isolates. Serotyping was achieved successfully with live and formalin-inactivated AHSVs, with isolates of virus after low and high passage through either tissue culture or suckling mouse brain, with viruses isolated from widely separated geographical areas and with viruses isolated up to 37 years apart. Overall, this RT-PCR provides a rapid and reliable method for the identification and differentiation of the nine AHSV serotypes, which is vital at the start of an outbreak to enable the early selection of a vaccine to control the spread of disease.

African Horse Sickness↗

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.

Alveolitis, Extrinsic Allergic↗

Antigens of Streptococcus mutans: isolation of a serotype-specific and a cross-reactive antigen from walls of strain V-100 (serotype e).

Two cell wall-associated polysaccharide antigens were extracted from purified cell walls of Streptococcus mutans serotype e strain V-100. One of these purified antigens (I) is specific for serotype e, whereas the other (II) has antigenic determinants reactive with both heterologous anti-serotype c serum (GS-5) and the homologous (e) serum. When crude formamide extracts of V-100 cell walls were loaded onto a Cellex-D column and eluted with a linear gradient of ammonium carbonate (0.02 to 0.40 M), the two products mentioned above could be recovered. The purified, antigenically reactive products (I and II) were each composed only of rhamnose and glucose in approximately a 2:1 molar ratio. Immunoelectrophoresis of the crude formamide extract, peak I, and peak II showed the purified fractions to have opposite mobilities and the crude extract to have a mobility that encompassed both purified peaks when reacted with homologous antiserum (V-100). When these three fractions were immunoelectrophoresed and reacted with heterologous anti-serotype c serum (GS-5), only the anodic portion of the crude V-100 formamide extract and purified peak II formed precipitates. Ouchterlony analysis with homologous antiserum produced precipitin patterns between the crude formamide extract and both purified peaks, indicating complete identity. However, only crude extracts of V-100 and the purified peak II material reacted with heterologous (c) antiserum; peak I did not cross-react in these Ouchterlony assays. Hapten inhibition studies revealed that a beta-glucosyl moiety is the immunodeterminant for serotype e and is present on each purified fraction. The basis of the cross-reaction between anti-c sera and the purified antigen II of e is discussed.

Cell Wall↗

Classification of Neisseria meningitidis group B into distinct serotypes. II. Extraction of type-specific antigens for serotyping by precipitin techniques.

Over 10 distinct serotypes of group B Neisseria meningitidis have been found to date by using a sensitive microbactericidal assay developed by the authors. The serotype antigens have now been extracted by hot acid or saline extraction procedures. It was found that these extracted serotype antigens may be used in a simple capillary precipitin method. This method uses unadsorbed, undiluted rabbit antisera. In the capillary precipitin method a 3+ to 4+ reaction was considered significant. The microbactericidal assay and capillary precipitin methods for serotyping group B meningococci show excellent agreement. Group B meningococci were also serotyped by an agar gel double diffusion technique. The latter technique conserves reagents and has the further advantage that it does not show the minor cross-reactions observed in the capillary precipitin method. Thus two simple, reproducible methods for serological typing of group B meningococci have been developed. These methods developed for the serological typing of group B meningococci will aid in epidemiological studies of meningococcal disease. They may also be of value for selecting suitable strains for vaccine production.

Adsorption↗

Evidence for a hybrid genomic island in verocytotoxin-producing Escherichia coli CL3 (serotype O113:H21) containing segments of EDL933 (serotype O157:H7) O islands 122 and 48.

Genomic O island 122 (OI-122) of the verocytotoxin-producing Escherichia coli (VTEC) strain EDL933 contains four putative virulence genes, Z4321, Z4326, Z4332, and Z4333. However, strain CL3 (serotype O113:H21) contains only Z4321, not the other three genes. To determine whether Z4321 is part of a different genomic island in CL3, a region of 27,293 bp up- and downstream of Z4321 was sequenced and found to contain elements of two different EDL933 genomic islands (OI-48 and OI-122) and a Yersinia pestis-like hemolysin/adhesin gene cluster. The region contained OI-48 genes Z1635, Z1636, and Z1637 at the left terminus and Z1641, Z1642, Z1643, and Z1644 at the right. The middle portion consisted of OI-48 gene Z1640, which was separated into three fragments by genomic segments including the Y. pestis cluster and EDL933 OI-122 genes Z4322, Z4321, and Z4318. In a PCR investigation of 36 VTEC strains of different serotypes, intact Z1640 was present in strains of serotypes O157:H7, O26:H11, O103:H2, O111:NM, and O145:NM, which are associated with hemolytic uremic syndrome and outbreaks. In contrast, fragmented Z1640 was seen in strains of nonepidemic serotypes, such as O91:H21 and O113:H21, and in animal serotypes that have not been associated with human disease, indicating that Z1640 might be a virulence gene.

Adhesins, Escherichia coli↗