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Improved diagnostic medium for separation of Cryptococcus neoformans var. neoformans (serotypes A and D) and Cryptococcus neoformans var. gattii (serotypes B and C).

A simple new agar medium containing L-canavanine, glycine, and bromthymol blue was found to give a clearer and more accurate distinction between serotype A or D (Cryptococcus neoformans var. neoformans) and serotype B or C (C. neoformans var. gattii) than creatinine-dextrose-bromthymol blue or glycine-cycloheximide-phenol red media. Among 143 isolates of serotype A or D and 70 isolates of serotype B or C, the new medium correlated completely with the serotype, whereas nearly 11% of these isolates gave discrepant reactions with creatinine-dextrose-bromthymol blue and glycine-cycloheximide-phenol red media.

Cryptococcus↗

New porcine rotavirus serotype antigenically related to human rotavirus serotype 3.

Serotyping of porcine rotaviruses isolated in MA104 cells from Australian piglets with diarrhea showed that two strains belonged to serotype 3 and one strain was antigenically similar to the OSU strain of porcine rotavirus (serotype 5). In addition, neutralizing antibodies to human rotavirus serotype 4 (ST-3 strain) were detected in serum samples from sows in one area, and so it seems probable that porcine rotaviruses of at least three serotypes occur in Australia.

Animals↗

Monoclonal antibodies to Pasteurella haemolytica serotype 1 lipopolysaccharide: demonstration of antigenic similarities among several serotypes.

Murine monoclonal antibodies (MAbs) were produced which were specific for Pasteurella haemolytica serotype 1 lipopolysaccharide (LPS). The MAbs also reacted with LPS present in a partially purified antigen derived from a saline extract of the organism. The epitope to which the MAbs were directed was a carbohydrate which was sensitive to oxidation with periodate, had a molecular weight between 14,000 and 25,000 as determined by immunoblotting, and was present in a crude O-antigen preparation of P. haemolytica LPS. The MAbs did not react with purified capsular polysaccharide from P. haemolytica serotype 1. In an enzyme-linked immunosorbent assay, reaction of the MAbs with LPS obtained from 14 gram-negative bacteria failed to detect any cross-reactivity with P. haemolytica LPS. However, the MAbs detected antigenic similarities among P. haemolytica serotypes 1, 5, 6, 7, 8, and 12 and, to a lesser extent, 4 and 14. These studies indicate that the LPS-O-antigens from several P. haemolytica serotypes have similar epitopes and may be partially responsible for shared antigenicity among serotypes.

Animals↗

The common ovine Shiga toxin 2-containing Escherichia coli serotypes and human isolates of the same serotypes possess a Stx2d toxin type.

Shiga toxin 2 (Stx2) has been reported as the main Shiga toxin associated with human disease. In addition, the Stx2 toxin type can have a profound impact on the degree of tissue damage in animal models. We have characterized the stx(2) subtype of 168 Shiga toxin-producing Escherichia coli (STEC) isolates of which 146 were derived from ovine sources (principally feces and meat) and 22 were isolated from humans. The ovine STEC isolates were of serotypes that have been shown to occur commonly in the gastrointestinal tract of healthy sheep. The major stx(2) subtype in the ovine isolates was shown to be stx(2d-Ount) (119 of 146 [81.5%]) and was predominantly associated with serotypes O75:H(-)/H8/H40, O91:H(-), O123:H(-), O128:H2, and OR:H2. However, 17 of 18 (94.4%) ovine isolates of serotype O5:H(-) possessed a stx(2d-O111/OX3a) subtype. Furthermore, STEC isolates of serotypes commonly found in sheep and recovered from both clinical and nonclinical human infections also contained a stx(2d) (stx(2d-Ount/O111/OX3a)) subtype. These studies suggest that a specific stx(2) subtype(s) associates with serotype and may have important epidemiological implications for tracing sources of E. coli during outbreaks of STEC-associated diseases in humans.

Animals↗

Cryptococcus neoformans var. neoformans (serotype D) strains are more susceptible to heat than C. neoformans var. grubii (serotype A) strains.

Cryptococcus neoformans var. neoformans (serotype D) and C. neoformans var. grubii (serotype A) differ in geographic prevalence and dermatotropism, with C. neoformans var. neoformans strains being more prevalent among isolates from temperate countries as well as from skin infections. Analysis of 19 strains from each serotype revealed wide variation in thermal susceptibility, with C. neoformans var. neoformans strains being more susceptible, on average, to heat killing. The results suggest a consistent explanation for the geographic differences between serotype A and D strains and for the dermatotropism of serotype D strains.

Colony Count, Microbial↗

Clade replacements in dengue virus serotypes 1 and 3 are associated with changing serotype prevalence.

The evolution of dengue virus (DENV) is characterized by phylogenetic trees that have a strong temporal structure punctuated by dramatic changes in clade frequency. To determine the cause of these large-scale phylogenetic patterns, we examined the evolutionary history of DENV serotype 1 (DENV-1) and DENV-3 in Thailand, where gene sequence and epidemiological data are relatively abundant over a 30-year period. We found evidence for the turnover of viral clades in both serotypes, most notably in DENV-1, where a major clade replacement event took place in genotype I during the mid-1990s. Further, when this clade replacement event was placed in the context of changes in serotype prevalence in Thailand, a striking pattern emerged; an increase in DENV-1 clade diversity was associated with an increase in the abundance of this serotype and a concomitant decrease in DENV-4 prevalence, while clade replacement was associated with a decline in DENV-1 prevalence and a rise of DENV-4. We postulate that intraserotypic genetic diversification proceeds at times of relative serotype abundance and that replacement events can result from differential susceptibility to cross-reactive immune responses.

Dengue↗

Induction of neutralizing antibodies specific to dengue virus serotypes 2 and 4 by a bivalent antigen composed of linked envelope domains III of these two serotypes.

There is no vaccine to prevent dengue fever, a mosquito-borne viral disease, caused by four serotypes of dengue viruses. In this study, which has been prompted by the emergence of dengue virus envelope domain III as a promising sub-unit vaccine candidate, we have examined the possibility of developing a chimeric bivalent antigen with the potential to elicit neutralizing antibodies against two serotypes simultaneously. We created a chimeric dengue antigen by splicing envelope domain IIIs of serotypes 2 and 4. It was expressed in Escherichia coli and purified to near homogeneity. This protein retains the antigenic identities of both its precursors. It elicited antibodies that could efficiently block host cell binding of both serotypes 2 and 4 of dengue virus and neutralize their infectivity (neutralizing antibody titers approximately 1:40 and ~1:80 for dengue virus serotypes 2 and 4, respectively). This work could be a forerunner to the development of a single envelope domain III-based tetravalent antigen.

Animals↗

Complete amino acid sequence of streptococcal PepM49 protein, a nephritis-associated serotype. Conserved conformational design among sequentially distinct M protein serotypes.

The complete amino acid sequence of PepM49, a peptic fragment of the group A streptococcal type 49 M protein, the antiphagocytic cell surface molecule of the bacteria, is described. This fragment retains the opsonic antibody epitope of the native molecule. The sequence of PepM49, as determined by automated Edman degradations of the uncleaved molecule, and its tryptic and chymotryptic peptides, consists of a total of 143 residues (Mr = 17,187). PepM49, a nephritis-associated M protein serotype, exhibits significant internal homology in its sequence. However, identical sequence repeats of the kind seen in the rheumatic fever-associated serotypes M5, M6, and M24, are absent in PepM49. PepM49 exhibits varying degrees of homology with the M5, M6, and M24 proteins, which is consistent with the existence of variable and conserved regions in the M protein molecule. Predictive analysis as well as CD measurements revealed a high propensity of the PepM49 molecule to assume an alpha-helical conformation. Furthermore, a heptad periodicity of the nonpolar residues, a characteristic of alpha-helical coiled-coil proteins, extends over the entire length of the PepM49 protein. The differences in the nonpolar residue distribution divide the PepM49 sequence into three distinct domains, similar to those seen earlier in the M5 and M6 proteins. Together, these studies establish a conserved conformational design for the sequentially diverse M protein serotypes. However, the pattern of heptad periodicity in the PepM49 protein is quite distinct from that present in the PepM5 and M6 proteins, suggesting distinct differences in structural features among conformationally similar M protein serotypes. This may have relevance to the pathological differences associated with these M protein serotypes.

Amino Acid Sequence↗

New serotype 2 and attenuated serotype 1 Marek's disease vaccine viruses: selected biological and molecular characteristics.

Two new Marek's disease vaccine viruses, Md11/75C/R2 (serotype 1) and 301B/1 (serotype 2), were evaluated in chickens with maternal antibodies (ab+) or without maternal antibodies (ab-). Strain Md11/75C/R2 was mildly pathogenic in ab--chickens, but this pathogenicity was markedly reduced in ab+ chickens. Md11/75C/R2 spread less by contact and replicated better, both in vivo and in vitro, than CVI988/C, another serotype 1 vaccine virus. Strain 301B/1 was similar to SB-1, another serotype 2 vaccine virus: both were nonpathogenic for ab--chickens, spread readily by contact, and replicated well in vivo. In vitro, 301B/1 grew more rapidly and produced larger plaques than SB-1. Notable characteristics of strain CVI988/C included absence of pathogenicity, poor replicative ability, and the absence of one epitope detected by a common serotype-1-specific monoclonal antibody. All four viruses could be distinguished from each other by restriction enzyme analysis of viral DNA. We conclude that Md11/75C/R2, although exceptionally protective, may require further attenuation. On the other hand, 301B/1, which in other studies induced higher levels of protection than SB-1, is nonpathogenic and may be considered for use as a commercial vaccine.

Animals↗

Isolation of bluetongue virus serotype 2 from cattle in Florida: serotype of bluetongue virus hitherto unrecognized in the Western Hemisphere.

A serotype of bluetongue virus (BTV) hitherto unrecognized in the Western Hemisphere was isolated from cattle in the United States. Clinical disease was not seen in the cattle which were part of a sentinel herd system in Florida designed for studying the epizootiology of BTV. The isolation of serotype 2 was the first recovery of a different serotype of BTV in the United States since 1967. At least 21 serotypes of BTV have been reported worldwide; the 5 serotypes of BTV now recognized in the United States are 2, 10, 11, 13, and 17.

Animals↗

Serotype-specific inhibition of colonization of the tonsils and nasopharynx of calves after Pasteurella haemolytica serotype A1 after vaccination with the organism.

Vaccination of cattle with a tissue culture-derived Pasteurella haemolytica serotype 1 vaccine elicited a serotype-specific inhibition of nasal and tonsillar colonization by the homologous serotype under field conditions. Calves (n = 101) originated from a single farm, where half the calves were vaccinated. The calves were delivered to an order-buyer barn 105 days later, and given a second dose of vaccine. At the order-buyer barn, calves were mixed with 27 calves, some of which had clinical signs consistent with respiratory tract disease. Also 12 of the original calves were infected with P haemolytica serotype 1 by tonsillar instillation. After 6 days at the order-buyer barn, calves were shipped 1,600 km by truck to a feedyard, and arrived the next day. Tonsillar wash and nasal secretion aspiration specimens were collected for culture of P haemolytica on days 1, 8, and 29 at the feedyard. Inhibition of colonization was evidenced by lower frequency of isolations from the vaccinates than from the nonvaccinates after transport to the feedyard. Selectively lowering the frequency of colonization by P haemolytica serotype 1 could reduce losses attributable to pneumonic pasteurellosis.

Animals↗

Identification of common antigens of serotype 1 and serotype 3 Pasteurella multocida in poultry expressed in vivo.

Eight groups of chicken immune sera and one group of turkey immune sera were used to identify unique in vivo-expressed antigens of Pasteurella multocida by Western immunoblotting. When antisera were prepared against the detergent-insoluble fraction of in vivo-grown P-1059, live X-73, live P-1059, live 86-1913, live P-1662, and live P-1702, they recognized four major antigens on immunoblots of the detergent-insoluble fraction of in vivo-grown serotype 1 and in vivo-grown serotype 3. These four antigens, which have approximate molecular weights of 204,000, 192,000, 179,000, and 153,000, were not recognized by antisera made against the detergent-soluble fraction of in vivo-grown P-1059, whole in vitro-grown inactivated X-73, or whole in vitro-grown inactivated P-1059. The results provide evidence for common antigens expressed by in vivo-grown serotype 1 and in vivo-grown serotype 3. These antigens are recognized by sera from chickens that have survived infection by various serotypes. The antigens are concentrated in the detergent-insoluble fraction of in vivo-grown bacteria and likely represent unique in vivo-expressed outer-membrane proteins.

Animals↗

Serotyping of Actinobacillus pleuropneumoniae serotype 5 strains using a monoclonal-based polystyrene agglutination test.

A polystyrene agglutination test has been developed for serotyping Actinobacillus pleuropneumoniae serotype 5a and 5b strains. Protein A-coated polystyrene microparticles were sensitized with a murine monoclonal antibody recognizing an epitope on serotype 5 LPS-O chain as shown by SDS-PAGE and Western blotting. A total of 205 A. pleuropneumoniae, strains including all 12 serotype reference strains and 13 strains representing 8 common bacterial species associated with swine or related to A. pleuropneumoniae, were tested by mixing 25 microL of polystyrene reagent with the same volume of a dense suspension of bacterial cells grown for 18 h. All A. pleuropneumoniae strains had been previously serotyped using standard procedures. The polystyrene agglutination test was rapid (less than 3 min) and easy to perform. Overall a very good correlation (97.3%) with the standard techniques was found. The sensitized polystyrene particles were stable for at least 6 mo.

Actinobacillus Infections↗

Present situation of serotyping of Pseudomonas aeruginosa in Japan and correlation among three kinds of commercially available serotyping kits.

We carried out the serotyping of 196 freshly isolated strains of Pseudomonas aeruginosa with international antigenic typing system (IATS) antibodies from Rougier Bio-Tech (RBT kit) and other two kinds of antibodies, from Meiji Seika Kaisha (Mei assay kit) and Denka Seiken (Seiken kit) to ascertain the relationship among the serotypes obtained by the different methods. All the test strains belonging to the serogroups A, C, E, F, G, H, I, J, and K were well correlated with each other with the Mei assay and the Seiken kits. However, 21 of 26 strains of serogroup M typed with the Mei assay kit were non-typable with the Seiken kit. It was confirmed that serogroups obtained with both these methods were closely related; 171 of the 196 strains of P. aeruginosa tested (87.2%) were classified into identical serogroups. From the serotyping results for P. aeruginosa strains with the Seiken and the RBT kits and with the Mei assay and the RBT kits, it was found that the serotypes of 172 of the 192 strains tested (89.6%) and those of 164 of the 170 strains tested (96.5%), respectively were well correlated. However, the serotyping of P. aeruginosa with the RBT kit may be problematic, as the kit did not contain the antisera agglutinated with the serogroup M strains of P. aeruginosa classified with the Mei assay and Seiken kits.

Journal Article↗

Cross-reactive, serotype- and monotype-specific neutralization epitopes on VP7 of serotype G3 and G5 porcine rotavirus strains.

VP7 specific monoclonal antibodies raised against serotype G5 porcine rotavirus strains isolated in Venezuela showed either a serotype G5- or monotype-specific pattern of reactivity by neutralization against a panel of 53 group A rotavirus isolates representative of all established G serotypes. Monoclonal antibodies raised against two G3 porcine strains were either specific for a subset of porcine G3 strains or reactive with another subset of porcine G3 strains and with most G5 strains. Neither were reactive with G3 strains from other species. Analysis of neutralization resistant mutants selected with these monoclonal antibodies indicated that epitopes defined by cross-reactive, serotype- and monotype-specific monoclonal antibodies overlap functionally and that binding and neutralization by these antibodies depended on specific amino acid residues in the region A or C of VP7. Results indicate that a high degree of monotypic variation occurs among G5 and G3 porcine rotavirus strains and the existence of at least one common epitope shared by G5 and G3 porcine strains, in the major neutralization domain of these VP7s.

Amino Acid Sequence↗

The cloning of full-length genome segments 2, 5, 6, and 8 of bluetongue virus (BTV) serotype 17 and studies of their genetic relatedness to United States BTV serotypes.

The double-stranded (ds) RNA genome segments 2, 5, 6, and 8, which encode the outer capsid proteins P2 and P5, and the two nonstructural proteins, NS1 and NS2, respectively, of bluetongue virus (BTV) serotype 17 have been cloned into pBR322. The length of the cloned genes indicates that the entire respective dsRNA genome has been cloned in each case. The four cloned genes were used as 32P-labeled probes to hybridize to PAGE-separated United States BTV serotypes 2, 10, 11, 13, and 17. Of these, the segment 6 clone was identified as being highly conserved and hybridized to all serotypes. Segment 8 was less conserved and segment 5 even less. The segment 2 clone was serotype specific. None of the probes hybridized with dsRNA from epizootic hemorrhagic disease virus (EHDV).

Animals↗

Characterization of lipopolysaccharides from four Pasteurella haemolytica serotype strains: evidence for presence of sialic acid in serotypes 1 and 5.

Highly purified lipopolysaccharides (LPS) obtained from four strains of Pasteurella haemolytica representative of four different serotypes were studied to ascertain their overall structural elements and sugar and fatty acid compositions. SDS-PAGE analysis revealed that each LPS was of the smooth-type although they differed in migration patterns. Somewhat unusual features of these LPS included the presence of: (a) rhamnose in the core oligosaccharides of serotypes 2 and 3; and (b) sialic acid in the LPS of serotypes 1 and 5. The fatty acids, myristic, hydroxymyristic and palmitic occur in essentially equivalent amounts in each of these LPS. In addition, stearic acid was present in small amounts of serotypes 1 and 5.

Amino Sugars↗

Adeno-associated virus vectors serotyped with AAV8 capsid are more efficient than AAV-1 or -2 serotypes for widespread gene delivery to the neonatal mouse brain.

Adeno-associated virus (AAV) vectors have gained a preeminent position in the field of gene delivery to the normal brain through their ability to achieve extensive transduction of neurons and to mediate long-term gene expression with no apparent toxicity. In adult animals direct infusion of AAV vectors into the brain parenchyma results in highly efficient transduction of target structures. However AAV-mediated global delivery to the adult brain has been an elusive goal. In contrast, widespread global gene delivery has been obtained by i.c.v. injection of AAV1 or AAV2 in neonates. Among the novel AAV serotypes cloned and engineered for production of recombinant vectors, AAV8 has shown a tremendous potential for in vivo gene delivery with nearly complete transduction of many tissues in rodents after intravascular infusion. Here we compare the efficiency of an AAV8 serotyped vector with that of AAV1 and AAV2 serotyped vectors for the extent of gene delivery to the brain after neonatal injection into the lateral ventricles. The vectors all encoded green fluorescent protein (GFP) under control of a hybrid CMV enhancer/chicken beta-actin promoter with AAV2 inverted terminal repeats, but differed from each other with respect to the capsid type. A total of 6.8 x 10(10) genome copies were injected into the lateral ventricles of postnatal day 0 mice. Mice were killed at postnatal day 30 and brains analyzed for distribution of GFP-positive cells. AAV8 proved to be more efficient than AAV1 or AAV2 vectors for gene delivery to all of the structures analyzed, including the cerebral cortex, hippocampus, olfactory bulb, and cerebellum. Moreover the intensity of gene expression, assessed using a microarray reader, was considerably higher for AAV8 in all structures analyzed. In conclusion, the enhanced transduction achieved by AAV8 compared with AAV1 and AAV2 indicates that AAV8 is the superior serotype for gene delivery to the CNS.

Animals↗