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PubMed2003

Distribution of Actinobacillus actinomycetemcomitans serotypes and Porphyromonas gingivalis in Japanese adults.

Strains of the bacterium Actinobacillus actinomycetemcomitans found in the human oral cavity are divided into five serotypes, a, b, c, d, and e. In this study, A. actinomycetemcomitans serotypes and Porphyromonas gingivalis were isolated from 656 subgingival sites in systemically healthy Japanese adults. A. actinomycetemcomitans was detected in 19.5% of 328 Japanese subjects, while 27.1% of subjects were positive for P. gingivalis. Of 75 A. actinomycetemcomitans-positive sites, only one serotype was detected in 39 sites (52.0%). The numbers of sites in which two different serotypes and three different serotypes were detected were 18 (25.0%) and 7 (9.3%), respectively. A. actinomycetemcomitans serotype c was detected more frequently in sites that were positive for both P. gingivalis and A. actinomycetemcomitans (76.9%) than in sites that were P. gingivalis-negative and A. actinomycetemcomitans-positive (33.9%). In addition, serotype c was detected much more frequently than the other serotypes (<16%) in sites that were positive for both P. gingivalis and A. actinomycetemcomitans. These findings suggest that the characteristics of serotype c may differ from those of the other serotypes. This report is the first to use PCR to describe the distribution of A. actinomycetemcomitans serotypes in humans and to examine the association between the distribution of A. actinomycetemcomitans serotypes and the presence of P. gingivalis.

Adult↗
PubMed1996

Antibodies against 12 serotypes of Actinobacillus pleuropneumoniae in finnish slaughter sows.

To determine the prevalence of A. pleuropneumoniae serotypes in Finnish pig populations, 692 blood samples of sows were randomly collected from Finnish slaughterhouses. These were assayed with a direct ELISA for 12 Actinobacillus pleuropneumoniae serotypes. The specificity of the ELISA was tested using rabbit antisera against these serotypes. Cross-reactions were detected between serotypes 6 and 8 and between serotypes 1, 9 and 11, and serotype 5 antiserum reacted with serotype 6 antigen, but the other serotypes did not cross-react. When assaying the blood samples serotype 3 and 2 antibodies were found in 51% and 26% of samples, respectively. Other serotypes were found only in smaller numbers. Most of the samples, 61%, had antibodies towards some serotype of A. pleuropneumoniae. Antibodies towards serotypes 2 and 3 were found in pigs throughout Finland.

Actinobacillus Infections↗
PubMed1994

Serological and Ecological Characteristics of a Nodule-Dominant Serotype from an Indigenous Soil Population of Rhizobium leguminosarum bv. trifolii.

Although at least 13 antigenically distinct serotypes of Rhizobium leguminosarum bv. trifolii exist in an Abiqua silty clay loam soil, one serotype, AS6, occupies >/=50% of the root nodules formed on field-grown subclover and between 33 and 78% of the nodules formed on five annual clover species grown in the same soil under laboratory conditions. The dominance of subclover nodules by serotype AS6 was reproducible over a 4-year sampling period and throughout the entire 200- by 100-m pasture examined. Serotype AS6 was composed of three antigenically distinct subtypes (AS6-a, AS6-b, and AS6-c). Each subtype contributed about one-third of the AS6 isolates recovered from nodules of field-grown subclover plants and maintained similar population densities in nonrhizosphere and rhizosphere soil. Rhizobia with the AS6 antigenic signature accounted for from 20 to 100% of the soil populations of R. leguminosarum in arable and pasture soils under legumes throughout the state of Oregon. Over a 12-month period, the population densities of the serotype AS6 complex and three minor nodule-occupying serotypes (AG4, AP17, and AS21) were measured in the rhizospheres of field-grown subclover and orchard grass and in nonrhizosphere Abiqua soil. Regardless of season or serotype, the orchard grass rhizosphere effect was minimal, with the ratio between rhizosphere and nonrhizosphere serotype population densities ranging between 2.5 (midsummer) and 10.5 (spring). In contrast, the magnitude of the subclover rhizosphere effect varied seasonally and among serotypes. Between October and December the ratios for all serotypes were similar (12.5 to 25.5). However, in the spring (April and May), the magnitude of the rhizosphere effect varied among the indigenous serotypes (ratios, 10.5 to 442) and for minor nodule-occupying serotypes AS21 (ratio, 442) and AP17 (ratio, 47) was as great as, or even greater than, the magnitude of the rhizosphere effect observed with the AS6 complex (ratio, 65.5).

Journal Article↗
PubMed1979

Protection against group B meningococcal disease: evaluation of serotype 2 protein vaccines in a mouse bacteremia model.

A mouse bacteremia model was used to evaluate the immunogenicity and protection against challenge provided by five different meningococcal serotype 2 vaccines. Mice vaccinated with serotype 2 protein vaccines had levels of bacteremia reduced by at least 100-fold after challenge with group B serotype 2 miningococci. Mice vaccinated with serotype 2 protein vaccine and challenged with group C serotype 2 meningococci showed 10-fold or less reduction in bacteremia. Vaccines were primarily serotype specific since no increase in protection was observed after challenge with either group B serotype 4 or group C nontypable meningococci. Serotype 2 antibody levels, measured by the bactericidal assay and the enzyme-linked immunosorbent assay 3 weeks after immunization, demonstrated a graded dose-response which correlated with protection up to 40 weeks after vaccination with a single 10- or 25-micrograms dose of serotype 2 protein vaccine. A 1-microgram booster dose of serotype 2 vaccine, given 2 weeks after primary immunization, significantly increased both bactericidal (P less than 0.01) and enzyme-linked immunosorbent assay (P less than 0.02) titers. The data obtained from the mouse bacteremia model indicate that serotype 2 protein vaccines are stable and immunogenic, and protect mice against challenge with group B serotype 2 meningococci.

Animals↗
PubMed2006

Detection of antibodies against serotypes 1 and 2 infectious bursal disease virus by commercial ELISA kits.

Two distinct serotypes of infectious bursal disease virus (IBDV) are recognized in chicken and turkey flocks in the United States. Serologic testing of chicken flocks for serotype 1 viruses is routinely performed to monitor disease status and vaccination. Earlier studies indicated that enzyme-linked immunosorbent assay (ELISA) test detects antibodies to both serotypes of the virus, while the virus neutralization (VN) test is serotype specific. It is useful to evaluate currently available commercial ELISA kits for their ability to differentiate between antibodies elicited by the two serotypes. Three trials were performed in which chickens were orally inoculated with either a high or a low dose of serotype 1 STC or serotype 2 OH strains of IBDV. Sera collected at 0, 7, 14, and 21 days from these chickens and antisera procured from naturally infected broiler (n=20) and layer (n=30) flocks were tested with five different commercial ELISA kits and by VN. All ELISA kits detected different levels of antibodies elicited against serotype 1 of the virus and moderate and high levels of antibodies against serotype 2 virus. A correlation existed between the ELISA and the VN titers of experimentally infected chickens. All serum samples tested from the commercial layer flocks and 65% of the broiler flocks had antibodies against the OH strain. However, no correlation between the VN titers and ELISA titers was observed for the commercial broilers and layers sera by the majority of the kits. The results indicated that currently available commercial ELISA kits detect antibodies elicited by the two serotypes of IBDV. Hence, the prevalence of serotype 2 antibodies in the flocks should be considered while determining antibody profiles of the flocks against serotype 1 viruses.

Animals↗
PubMed2004

Characterization of vaginal & rectal colonization with multiple serotypes of group B streptococci using multiple colony picks.

BACKGROUND & OBJECTIVES: There is paucity of information on vaginal and rectal colonization with multiple serotypes of group B streptococci (GBS). As part of an ongoing cohort study evaluating the natural history of vaginal and rectal colonization by GBS, the colonization with multiple serotypes was studied in 102 non-pregnant women aged 18-30 yr. METHODS: Up to ten separate colony picks of beta-haemolytic streptococci (total 1515 isolates) were selected from vaginal and rectal primary culture plates. The colonies were identified as GBS, and their capsular polysaccharides (CPS) serotypes determined using monospecific rabbit antisera for types Ia-VIII by double immunodiffusion in agarose (DID). A colony dot immunoblot (DB) assay, using monospecific rabbit antisera to purified type polysaccharides conjugated to tetanus toxoid, was developed to serotype efficiently the multiple colony picks of GBS. RESULTS: The CPS serotype distribution, examining only the 177 "a" or first colony picks from the 102 patients, was 30.5 per cent for Ia; 28.2 per cent for type III; 15.3 per cent for type II; and 13.6 per cent for type V. Only 2.8 per cent were nontypeable. Eighty of the 102 patients (78.4%) were colonized with only one serotype; 20 (19.6%) had two serotypes and two patients (2%) had three serotypes in their vaginal and/or rectal paired cultures. Overall, 91.9 per cent of the culture sites colonized with one to three CPS types (from the total number of colonies picked) were identified with a minimum of three colony picks. In 75 patients with vaginal/rectal pairs the GBS serotype concordance of only the "a" colony was 89.3 per cent and concordance decreased to 80 per cent when the serotype concordance of the total colony picks was analyzed. INTERPRETATION & CONCLUSION: In conclusion, there was a relatively high prevalence of serotype nonconcordance in this population, and 21.6 per cent of patients had multiple GBS serotypes.

Adolescent↗
PubMed2006

[Homology analysis of the extended-V region of the surface proteins in different serotype Streptococcus mutans].

OBJECTIVE: To analysis the homology among the extended-V region of the surface proteins in different serotype Streptococcus mutans (c, f, d, g) and to find out it's significance in anti-caries vaccine. METHODS: The DNA of the bacteria (standarded serotype c, d, f, g and partial serotype c clinicals) was extracted and the extended-V region (SrV+, 1 384-2 514 bp) was amplified using polymerase chain reaction (PCR). Then the products were assessed using restriction fragment length polymorphism (RFLP) by endonuclease Dde I. The genotypings were sequenced and analysised using the program of BLAST on NCBI Gene Bank database. RESULTS: About 1.13 kb fragments were produced both in serotype c and f, the serotype d and g were failed. The RFLP results showed that five different patterns(A, B, C, D, E) among the 117 PCR products were reveled by Dde I. The ration of the genotypings A and B were the most among the strains, the C was lower, the D and E respectively was 1 and 3 strains per genotype. OMZ175 (serotype f) was belong to B genotype. Selected one of the A, B, C genotypings to sequenced and blasted. Then the results of the blastn showed that the identities of the gene sequence were 92%-98% between the serotype c and serotype f, part sequence of the serotype g was homology with the SrV+ of the serotype c, the protein sequence among serotype c, d, f, g were 77%-82%. CONCLUSION: It is reasonable to use some putative pipetides to study the anti-caries vaccine among the extended-V regions of the surface proteins in different serotype (c, d, f, g) in S. mutans.

DNA, Bacterial↗
PubMed1990

[Chemical analysis and immunochemical characterization of serotype-specific antigens from the strains of Actinobacillus actinomycetemcomitans which were frequently found in the periodontal pockets of the patients of localized juvenile periodontitis].

Serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving. The extracts were purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. The purified polysaccharide antigens formed a single precipitin band with the corresponding anti-a, b or c serum on immunodiffusion. Analysis of component sugars by GLC, HPLC, GLC-MS, NMR together with specific optical rotation data showed that the serotype a antigen consisted of 6-Deoxy-D-talose, the serotype b antigen consisted of L-rhamnose and D-fucose, and the serotype c antigen consisted of 6-Deoxy-L-talose. Structural analysis indicated that these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1- (serotype a), -3)-alpha-D-Fucp-(1-2)-beta-L-Rhap-(1- (serotype b) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1- (serotype c). 13C and 1H-NMR analyses suggested that the serotype a and c polysaccharides carried approximately one acetyl group per two sugar residues, although the acetylated position was not identified. In quantitative precipitin inhibition tests, the component sugars showed very low inhibition, whereas the partial hydrolysates of these antigens were effective inhibitors. These results suggest that the serotype-specific antisera recognize larger oligosaccharide units.

Aggregatibacter actinomycetemcomitans↗
PubMedDate not supplied

Haemophilus pleuropneumoniae serotypes--cross protection experiments.

Pigs vaccinated with a killed 6-hour culture of Haemophilus pleuropneumoniae serotype 2 with Freund's incomplete adjuvant were not protected against challenge with serotypes 1, 5, 6 or 8. Equivalent results were obtained when pigs were vaccinated with serotypes 4 or 5 and challenged with serotype 2. In earlier studies of immunity induced by intranasal immunization with live H. pleuropneumoniae organisms, it was clearly shown that intranasal inoculation with one serotype of H. pleuropneumoniae would induce a strong immunity to both homologous and heterologous serotypes (Nielsen 1979). The present study has shown that cross immunity is not obtained with parenteral immunization. The results strongly suggest that the immune response of the pig to parenteral vaccination is different from the response seen after natural infection, and indicate that an important part of the defence mechanism against H. pleuropneumoniae infection is a local immune-barrier which is effective in preventing the bacterium from penetrating the mucosa. In earlier vaccination experiments 90 per cent of vaccinates were protected against homologous challenge (Nielsen 1976). In the present work a vaccine containing serotypes 1 through 6 was fully protective against serotypes 2 and 3 and also against serotype 8, which shares antigenic determinants with serotypes 3 and 6. These results indicate that the protection obtained by parenteral immunization is serotype-specific. Vaccines must therefore contain the serotypes existing in the swine population.

Animals↗
PubMed1982

Hemagglutinin of Haemophilus paragallinarum serotype 2 organisms: occurrence and immunologic properties of hemagglutinin.

Hemagglutinating properties of Haemophilus paragallinarum serotype 2 and serotype C against freshly collected and glutaraldehyde (GA)- fixed chicken RBC were investigated. Different from serotype 1, the nontreated organisms of serotype 2 and serotype C lacked hemagglutinating activity. However, when the organisms were treated with potassium thiocyanate (KSCN) and/or sonication, activity occurred not only against GA-fixed chicken RBC, but also against GA-fixed RBC of various animal species. The maximum hemagglutination titer (1:64 to 1:256) was obtained against GA-fixed RBC with the KSCN-treated organisms that were also sonicated. The activity was inactivated by heating at 100 C or by treatments with formalin or trypsin, but not by treatments with hyaluronidase or neuraminidase. By using KSCN-treated and sonicated organisms and GA-fixed chicken RBC, a detection of hemagglutination-inhibition (HI) antibody was possible. The HI tests showed that serotype 2 hemagglutinin was immunologically distinct from serotype 1 and that the HI antibody correlated to protective activity against challenge exposure with serotype 2 and serotype C. Chicks having HI antibody greater than 1:5 were protected against challenge exposure with homologous type, but were not protected with serotype 1. Applicability of the HI test was also shown for evaluating protective potency in the serotype 2 vaccine, as well as in the serotype 1 vaccine.

Animals↗
PubMed1987

Serotyping and subgrouping of some rotavirus strains in China.

This article reports for the first time in China the results of serotyping and subgrouping of some rotavirus strains obtained from faecal fluids of cases with infant diarrhoea. Infant diarrhoea rotavirus serotype 1 (Wa strain)-specific and serotype 2 (KUN strain)-specific hyperimmune sera, and infant diarrhoea rotavirus serotype 3-specific, rotavirus subgroup I-specific and subgroup II-specific monoclonal antibodies were used in serotyping and subgrouping by means of enzyme-linked immunosorbent assay of 14 rotavirus strains which had been identified by electron microscopy. Results showed that three out of four Beijing strains in 1982 belonged to serotype 2 and subgroup I rotavirus, one belonged to serotype 3 and subgroup II rotavirus; one out of nine Beijing strains in 1984 belonged to serotype 1 and subgroup II rotavirus, seven belonged to serotype 2 and subgroup I rotavirus, one belonged to serotype 3 and subgroup II rotavirus; and one Kunming strain in 1984 belonged to serotype 3 and subgroup II rotavirus.

Antibodies, Monoclonal↗
PubMed1993

Determination of bovine rotavirus G and P serotypes by polymerase chain reaction.

Among bovine rotaviruses there are two major G serotypes (G6 and G10) and three P serotypes (P1, P5, and P11, each of which is defined on the basis of the VP4 antigenic specificity of NCDV, UK and KK-3, respectively). The nucleotide sequence of a P11 gene (KK-3) was determined. The predicted KK-3 VP4 contained 772 amino-acids and showed 96% amino-acid identity with B223 VP4, an American prototype of P11 bovine rotavirus. Comparative analysis of the genes determining the G and P serotypes of bovine rotaviruses allowed us to develop polymerase chain reaction (PCR)-based assays which distinguished two G serotypes and three P serotypes commonly found in bovine rotaviruses. For determination of G serotypes, a 1013 bp fragment of the VP7 gene was first reverse-transcribed and then amplified with a pair of generic primers. In a second PCR amplification, the 5' generic primer and two different typing primers (either G6- or G10-specific) were used to generate fragments whose sizes served to identify the G serotype. Similarly, for determination of P serotypes, an 864 bp fragment of the VP4 gene was first reverse-transcribed and then amplified with another pair of generic primers. In a second PCR amplification, the 5' generic primer and three different typing primers, each one specific to one of the three P serotypes, were used to generate fragments whose sizes served to identify the P serotype. These assays were able to identify the G and P serotypes of six reference bovine rotavirus strains.

Animals↗
PubMed1998

Identification and characterization of nucleotide sequence differences in three virulence-associated genes of listeria monocytogenes strains representing clinically important serotypes.

Listeria monocytogenes is a Gram-positive, facultative intracellular bacterium that causes invasive, often fatal, disease in susceptible hosts. As a foodborne pathogen, the bacterium has emerged as a significant public health problem and has caused several epidemics in the United States and Europe. Three serotypes (1/2a, 1/2b, 4b) of L. monocytogenes are responsible for nearly 95% of all reported cases of human listeriosis. L. monocytogenes serotype 4b has caused all well-characterized foodborne epidemic outbreaks in North America and Europe between 1981 and 1993. However, most of the genetic studies to characterize virulence factors of L. monocytogenes have been done by using serotypes 1/2a and 1/2c. In this investigation, we examined three virulence-associated genes (hly encoding listeriolysin, plcA encoding phosphotidylinositol-specific phospholipase C, and inlA encoding internalin) of two serotype 4b and two serotype 1/2b strains. We chose these virulence-associated genes on the basis of published sequence differences among strains from Listeria subgroups containing serotypes 1/2a and 1/2c versus 4b, respectively. They correspond to sequence homologies that include very highly conserved (hlyA), highly conserved (plcA) and mostly conserved (inlA). We found by using nucleotide sequence analysis of the hly, plcA, and inlA genes, the two L. monocytogenes strains (including a strain associated with a foodborne disease outbreak in California in 1985) in this study, two serotype 1/2b strains from a study that we recently reported, and other similar published data for serotypes 1/2a, 1/2c, and 4b, had a high degree of sequence conservation at the gene and protein levels for all three genes. However, the sequences for the hly gene of L. monocytogenes strains of serotypes 1/2b and 4b were more closely related to each other and showed significant divergence from serotypes 1/2a and 1/2c. A unique nonsynonymous mutation was found in the hly gene of L. monocytogenes isolates that were associated with the 1985 California outbreak and were the epidemic phage type. When 158 L. monocytogenes isolates from the collection at the Centers for Disease Control and Prevention were screened, the mutation was found only in one other strain that had been isolated in California 3 years before the epidemic. Although the California epidemic clone was lactose negative, other L. monocytogenes serotype 4b isolates that were lactose negative did not possess the unique mutation observed in that epidemic clone.

Bacterial Proteins↗
PubMed1990

O-serotyping of Yersinia ruckeri with special emphasis on European isolates.

Yersinia ruckeri is the aetiological agent of enteric redmouth disease (ERM), an acute to chronic bacteraemic infection of salmonid fish. The O-serotypes of 127 isolates of Y. ruckeri obtained from Europe (96 isolates), North America (23 isolates), Australia (six isolates) and South Africa (two isolates), as well as four reference strains, were determined by slide agglutination test and microplate agglutination assay. A serotyping scheme is proposed based on heat-stable O-antigens; the serotypes were designated O1, O2, O5, O6 and O7. The proposed scheme is compared to serotyping schemes described by other authors. All five O-serotypes were present in both Europe and North America, whereas only serotype O1 isolates were identified in Australia and South Africa. These findings suggest that European and North American populations of Y. ruckeri are interrelated, thus supporting previous evidence which suggests that the organism was introduced into Europe from North America by the importation of asymptomatic infected carrier fish. Conversely, the results suggest that Australia and South Africa are more isolated from the dissemination of Y. ruckeri. Serotypes O5, O6 and O7 have not previously been recognized in Europe and these findings will have important implications on the diagnosis of ERM and on the vaccination of fish against this disease. It is suggested that the Australian isolate previously described as serotype III is a rough-type mutant and that other isolates described in the literature as serotype III have been incorrectly serotyped and are, in fact, serotype O1. To avoid further confusion it is suggested that the scheme described here be adopted for serological studies of Y. ruckeri.

Agglutination Tests↗
PubMed1994

Streptococcus bovis infections in pigeons: virulence of different serotypes.

In a first experiment, the relative virulence for pigeons of 5 strains of S. bovis was assessed by experimental inoculations. Two S. bovis serotype 1 strains, one serotype 2 strain and two serotype 3 strains were examined. One of the serotype 1 strains and the serotype 2 strain were isolated from pigeons that died from septicaemia. The other strains were isolated from cloaca samples of healthy pigeons. For each strain, 10-20 pigeons were intravenously inoculated with 1 x 10(9) CFU. Morbidity after infection with the serotype 1 and 2 strains varied between 75% and 90%. Disease signs included inability to fly, lameness, emaciation, production of slimy, green droppings, polyuria and sudden death. In groups of pigeons inoculated with the serotype 3 strains, morbidity was 0% and 6%, respectively. Results demonstrate that serotype 3 strains are less virulent for pigeons than serotype 1 and 2 strains. In a second experiment, bacteriological and histological examinations were performed on organs of pigeons serially killed between 1 and 10 days after experimental inoculation with an S. bovis serotype 3 strain of low virulence. Results were compared with results of studies carried out with a highly virulent serotype 1 strain. Notwithstanding bacterial spread and replication in various organs of inoculated pigeons, clinical disease was not observed and histological lesions were scarce and of limited extent.

Animals↗
PubMed2006

Cross-immunity and antibody responses to different immobilisation serotypes of Ichthyophthirius multifiliis.

Vaccination of channel catfish with either of two serotypes of the parasitic ciliate Ichthyophthirius multifiliis conferred protection against challenge infection by either serotype. Fish were vaccinated by intracoelomic injection with live theronts of isolate G5 (serotype D) or isolate G12 (a new serotype), which express different surface immobilisation antigens. Vaccination with live G12 theronts conferred complete protection against subsequent challenge by both serotypes while vaccination with G5 theronts elicited only partial protection against both serotypes. Vaccination with trophont lysates did not protect against challenge infection. Sera from vaccinated fish were tested in immobilisation assays, ELISAs, and Western blots. Serum antibodies recognised only immobilisation antigens of the serotype used for vaccination in immobilisation assays or on Western blots. No antigens common to both serotypes were identified by Western blots. In contrast, serum antibodies bound antigens in cell lysates from both serotypes by ELISA, demonstrating that antibodies recognising both serotypes are produced in response to infection, which presumably confer observed cross-serotype protection.

Animals↗
PubMed2006

Combined sigB allelic typing and multiplex PCR provide improved discriminatory power and reliability for Listeria monocytogenes molecular serotyping.

Conventional serotyping has traditionally been used to subtype Listeria monocytogenes, but has several limitations, including low discriminatory power and poor reproducibility. Molecular serotyping methods have been developed for L. monocytogenes, but generally show limited discriminatory power and high misclassification rates. We selected 157 Listeria isolates to evaluate a combination of a previously described multiplex PCR assay and sigB allelic typing as an alternative molecular serotyping and subtyping strategy for L. monocytogenes. While the multiplex PCR assay differentiated five L. monocytogenes subtypes (Simpson's Index of Discrimination [SID]=0.78), including classification of the most common disease-associated serotypes (1/2a, 1/2b, 1/2c, and lineage I 4b) into four distinct groups, it misclassified 3.8% of the isolates studied here. sigB allelic typing differentiated 29 subtypes (SID=0.87) and also allowed identification of lineage III L. monocytogenes, which could not be differentiated from the other Listeria spp. by the multiplex PCR assay. sigB allelic typing failed to differentiate serotype 1/2c and 1/2a isolates and one sigB allelic type included serotype 4b and 1/2b isolates. A molecular serotyping approach that combines multiplex PCR and sigB sequence data showed increased discriminatory power (SID=0.91) over either method alone as well as conventional serotyping (SID=0.87) and classifies the four major serotypes (i.e., 1/2a, 1/2b, 1/2c, and 4b) into unique subgroups with a lower misclassification rate as compared to the multiplex PCR assay. This combined approach also differentiates lineage I serotype 4b isolates from the genetically distinct serotype 4b isolates classified into lineage III.

Alleles↗
PubMed2001

Study of antigenic heterogeneity among Actinobacillus pleuropneumoniae serotype 7 strains.

Actinobacillus pleuropneumoniae serotype 7 strains were studied for their antigenic heterogeneity using rabbit polyclonal hyperimmune sera against all the known twelve reference strains of A. pleuropneumoniae and a battery of different serological tests such as coagglutination (COA), immunodiffusion (ID), indirect hemagglutination (IHA), counterimmunoelectrophoresis (CIE), rapid dot-ELISA (RDE), serum soft-agar (SSA) and growth agglutination (GA). Reference serotype 7 strain (WF83) showed cross-reactivity with reference serotype 1B strain but not with other serotypes. Field serotype 7 strains showed cross-reactivities with serotypes 1A, 1B, 4, 9, 10, and 11 in COA, ID, and CIE tests, but not in IHA test. Two field strains of serotype 7 (90-3182 and 86-1411) which appeared to be different from the typical serotype 7 strains were selected for further antigenic characterization by SDS-PAGE, Western blot, and Tricine SDS-PAGE assays, and identified as serotypes 1 and 7, respectively. For serotyping atypical strains, it is suggested to use Western blot assay as a confirmatory test to identify serotype-specific capsular and somatic antigens.

Actinobacillus pleuropneumoniae↗