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PubMed2004

Multilocus sequence typing of serotype III group B streptococcus and correlation with pathogenic potential.

Serotype III group B streptococcus (GBS) causes more invasive disease in infants than do other serotypes in North America. We used multilocus sequence typing to identify clones within 28 invasive serotype III GBS isolates identified from a population-based study and 55 serotype III GBS colonizing isolates from a cohort of women from the same population. Ten allelic sequence types (STs) were identified and primarily involved 2 profiles: ST-19 (57.1% of invasive isolates and 58.2% of colonizing isolates) and ST-17 (32.1% of invasive isolates and 29.1% of colonizing isolates). On concatenation, the 10 allelic profiles converged into 3 groups. Group 1 consisted of ST-19 complex, ST-36, and ST-1, and was closely related to reference genome 2603V/R (serotype V). Group 2 consisted of ST-17 complex. Group 3 consisted of ST-23 complex and was closely related to the serotype III genome strain NEM 316. Neither of the major sequence types or groups was more commonly associated with invasion (P=.61) or with lower levels of maternal capsular polysaccharide-specific IgG (0.89 microg/mL and 0.39 microg/mL, respectively) for ST-19 and ST-17 (P=.86). The close association of genomic strain 2603V/R (serotype V) with ST-19 suggests that the phenomenon of capsule switching may have occurred.

Alleles↗

PubMed2005

Serum serotype-specific pneumococcal anticapsular immunoglobulin g concentrations after immunization with a 9-valent conjugate pneumococcal vaccine correlate with nasopharyngeal acquisition of pneumococcus.

BACKGROUND: Immunization with pneumococcal conjugate vaccines (PCVs) reduces nasopharyngeal colonization by Streptococcus pneumoniae. We attempted to correlate postvaccination serum serotype-specific pneumococcal anticapsular immunoglobulin (Ig) G concentrations with new acquisitions of vaccine-type (VT) serotypes and the VT-related serotype 6A. METHODS: A total of 132 day care center attendees aged 12-35 months received a 9-valent PCV (PnCRM9) and were followed for 2 years for new nasopharyngeal acquisitions of S. pneumoniae. A total of 132 control subjects received a meningococcus type C conjugate vaccine. Serum serotype-specific pneumococcal anticapsular IgG concentrations were determined at 1 month after complete immunization. RESULTS: A logistic regression model of the probability of having a new acquisition of S. pneumoniae (for serotypes 9V, 14, 19F, and 23F) as a function of the IgG concentration showed a negative coefficient, indicating that higher IgG concentrations led to a decreasing probability of having a new acquisition, and achieved statistical significance for serotypes 14 and 19F. Similarly, a new acquisition of serotype 6A was shown to be significantly inversely related to the anti-6B IgG concentration. An effect of the IgG concentration on duration of carriage was not demonstrated. CONCLUSION: The magnitude of herd protection against S. pneumoniae provided by a PCV may depend on the magnitude of IgG concentrations.

Antibodies, Bacterial↗

PubMed2006

Diversity and antibiotic resistance among nonvaccine serotypes of Streptococcus pneumoniae carriage isolates in the post-heptavalent conjugate vaccine era.

BACKGROUND: In response to the selective pressure of pneumococcal conjugate vaccine, increased asymptomatic carriage of antibiotic-nonsusceptible nonvaccine serotypes (NVTs) has been observed. Possible mechanisms include de novo acquisition of resistance, serotype switching, introduction of new clones, and expansion of existing clones. METHODS: To investigate the process of increased antibiotic nonsusceptibility among replacing serotypes, we applied multilocus sequence typing to samples of 126 and 222 pneumococci collected in 2001 and 2004, respectively, from the nasopharynges of children <7 years of age in 16 Massachusetts communities. RESULTS: We found no evidence of penicillin resistance due to either serotype switching or de novo acquisition. Nonetheless, resistance increased through the expansion of previously recognized clones of NVTs, particularly in serotypes 19A, 15A, and 35B. In 19A, several unrelated clones increased in frequency, whereas, in the other 2 serotypes, single resistant lineages were responsible for the increased prevalence of resistant strains. CONCLUSIONS: The decreased prevalence of antibiotic resistance with the introduction of heptavalent pneumococcal conjugate vaccine is likely to be partially eroded over time as vaccine-included serotypes are replaced by resistant clones of NVTs. The clinical significance of this will depend on the pathogenic potential of replacing clones to cause local (e.g., otitis media) or invasive disease.

Anti-Bacterial Agents↗

PubMed1997

Epidemiology of pneumococcal serotypes and conjugate vaccine formulations.

The incidence of bacteremia and meningitis due to Streptococcus pneumoniae is highest among preschool-age children, particularly those < 2 years of age. Clinical trials of capsular polysaccharide vaccines among young children have been disappointing. Conjugation of bacterial polysaccharides to proteins can increase antibody responses following vaccination of young children. Most conjugate vaccines proposed to date have been seven-valent. To identify serotypes most commonly associated with infection in young children, we serotyped pneumococcal isolates submitted to the CDC through national surveillance from 3884 children < 6 years old with pneumococcal bacteremia (n = 3169), meningitis (n = 401), or otitis media (n = 314) from 1978 to 1994. Seven serotypes (14, 6B, 19F, 18C, 23F, 4, and 9V) accounted for 3045 (78%) isolates. A conjugate pneumococcal vaccine protecting against these seven serotypes and serologically cross-reactive serotypes could potentially prevent 86% of bacteremia, 83% of meningitis, and 65% of otitis media cases. The proportion of isolates covered by such a vaccine increased from 78% to 87% from 1978 to 1994. Of 70 isolates submitted during 1992-1994 which were nonsusceptible to penicillin (minimal inhibitory concentration [MIC] > 0.1 microgram/mL, 56 (80%) were among the seven most prevalent serotypes. All 21 isolates resistant to penicillin (MIC > or = 2.0 micrograms/mL) were among these seven serotypes.

Adolescent↗

PubMed2006

Incidence and duration of group B Streptococcus by serotype among male and female college students living in a single dormitory.

Group B Streptococcus causes a variety of morbid and sometimes fatal conditions affecting individuals of all age groups. There are nine known serotypes of this Gram-positive coccus but few estimates of the incidence and duration of its colonization and none by serotype in the literature. In 2001, the authors conducted a prospective cohort study among 257 men and women living in a single dormitory in Ann Arbor, Michigan. The 3-week incidence with any serotype was 11.3% (+/-3.9%) among women and 8.8% (+/-3.0%) among men; 3-week incidence rates were highest for serotype V (4.7% for women and 3.5% for men) and type Ia (2.3% for women and 2.4% for men), with no significant differences by gender. The estimated average duration of any group B Streptococcus colonization was longer for women (13.7 weeks) than men (8.5 weeks); serotype Ia was carried an average of 6.5 weeks longer in women, and serotype III was carried 4.9 weeks longer. Colonization with more than one serotype occurred significantly less than would be expected by chance (p <<< 0.001). Based on the overall incidence, transmission occurred between roommate pairs at the rate expected. Group B Streptococcus colonization is frequent and dynamic, but it is not transmitted by casual contact.

Adolescent↗

PubMed1979

A study of 666 strains of Candida albicans: correlation between serotype and susceptibility to 5-fluorocytosine.

The minimal inhibitory concentrations (MICs) of 5-fluorocytosine (5-FC) and the serotypes were determined for 666 strains of Candida albicans isolated from white patients in Canada. Of these strains, 495 (74.3%) were serotype A and 71 (25.7%) were serotype B. Resistance to 5-FC (MIC, greater than or equal to 25 microgram/ml) was observed in 11.3% of the serotype A strains and in 49.7% of the strains of serotype B. Most specimens were from the urogenital and respiratory tracts. The results showed the difference between the distribution of the two serotypes of C. albicans in North America and that in Europe. Serotyping of C. albicans strains by indirect immunofluorescence is a rapid means of predicting the de novo sensitivity of this year to 5-FC. The specificity of this technique for the isolated strains was approximately 79%.

Animals↗

PubMed1990

Serotyping of human group A rotavirus with oligonucleotide probes.

Rotaviruses (RV) in stools of children with diarrhea in Thailand were serotyped by monoclonal enzyme immunoassay (MEIA), and RNA extracted from these specimens were tested for hybridization with oligonucleotides constructed from the nucleotide sequences of VP7 of human serotypes 1, 2, 3, and 4. Of 178 specimens that contained RV as identified with a monoclonal antibody to group A RV, 84% (149/178) hybridized with serotype-specific oligonucleotides, and 42% (74/178) were serotyped by MEIA (P less than .001). Of the 74 specimens that were serotyped by MEIA, 92% (35/38) of type 1, 97% (34/35) of type 2, and the one type 4 RV hybridized with the HuG1Ac, HuG2Ac, and HuG4Ac oligonucleotides, respectively. RV strains identified in children in Thailand in 1987 and 1988 to which a serotype could be assigned by either method were either type 1, type 2, or, less often, type 4. Testing RV for hybridization with oligonucleotides for genes encoding VP7 is an alternate method of determining RV serotypes.

Antibodies, Monoclonal↗

PubMed1990

Serotype variation of human group A rotaviruses in two regions of the USA.

The first longitudinal study of group A rotavirus serotype distribution in the USA is reported. ELISAs incorporating neutralizing monoclonal antibodies specific for the VP7 protein of serotypes 1, 2, 3, and 4 were used to determine the antigenic variation of group A rotaviruses in two collections of stool specimens. Stool samples were collected from children hospitalized during 1979-1989 at Texas Children's Hospital, Houston, and from children from a more rural population hospitalized during 1981-1989 in the north-central USA. The predominant serotype varied from year to year in Houston, with serotypes 1, 3, and 4 each predominant in 1 or more years. In the north-central population only serotype 1 was predominant each year. Within a single rotavirus season in the Houston area, serotypes were not equally distributed by week of the season or county of residence. These differences in the distribution of serotypes have broad implications for the design and interpretation of vaccine programs.

Age Factors↗

PubMed1995

Serotype distribution of Streptococcus pneumoniae infections among preschool children in the United States, 1978-1994: implications for development of a conjugate vaccine.

Conjugation of pneumococcal polysaccharide antigens to a protein carrier may improve protective immunity after vaccination of young children, an age group with high incidence of Streptococcus pneumoniae infection and poor immune responses to polysaccharide vaccines. To identify serotypes most commonly associated with infection in young children, pneumococcal isolates were serotyped from 3884 children < 6 years old (including 3007 < 2 years old) with pneumococcal bacteremia (n = 3169), meningitis (n = 401), or otitis media (n = 314). The isolates were submitted as part of a national surveillance during 1978-1994. Seven serotypes (14, 6B, 19F, 18C, 23F, 4, and 9V) accounted for 3045 isolates (78%). A conjugate pneumococcal vaccine protecting against these seven serotypes and serologically cross-reactive serotypes could potentially prevent 86% of bacteremia and 83% of meningitis but only 65% of otitis media cases. The proportion of isolates covered by such a vaccine increased from 78% to 87% during 1978-1994. Surveillance for pneumococcal serotypes causing infection is needed to detect shifts in serotype distribution over time.

Bacterial Vaccines↗

PubMed2004

Whole genome comparisons of serotype 4b and 1/2a strains of the food-borne pathogen Listeria monocytogenes reveal new insights into the core genome components of this species.

The genomes of three strains of Listeria monocytogenes that have been associated with food-borne illness in the USA were subjected to whole genome comparative analysis. A total of 51, 97 and 69 strain-specific genes were identified in L.monocytogenes strains F2365 (serotype 4b, cheese isolate), F6854 (serotype 1/2a, frankfurter isolate) and H7858 (serotype 4b, meat isolate), respectively. Eighty-three genes were restricted to serotype 1/2a and 51 to serotype 4b strains. These strain- and serotype-specific genes probably contribute to observed differences in pathogenicity, and the ability of the organisms to survive and grow in their respective environmental niches. The serotype 1/2a-specific genes include an operon that encodes the rhamnose biosynthetic pathway that is associated with teichoic acid biosynthesis, as well as operons for five glycosyl transferases and an adenine-specific DNA methyltransferase. A total of 8603 and 105 050 high quality single nucleotide polymorphisms (SNPs) were found on the draft genome sequences of strain H7858 and strain F6854, respectively, when compared with strain F2365. Whole genome comparative analyses revealed that the L.monocytogenes genomes are essentially syntenic, with the majority of genomic differences consisting of phage insertions, transposable elements and SNPs.

Base Composition↗

PubMed1980

Cryptococcus neoformans serotype groups encountered in Oklahoma.

Eighty clinical and 28 soil isolates of C. neoformans obtained in Oklahoma were separated into A-D and B-C serotype groups utilizing creatinine-dextrose agar with bromthymol blue. Previously, serotype B-C clinical isolates have been frequent only in patients from Southern California where as many as 50% of the isolates are of this type. In contrast, in patients from the rest of the United States the B-C frequency has been only 6%. Of the 80 C. neoformans isolates from Oklahoma patients, 12 (15%) were serotype B-C. One-half of these 12 Oklahoma patients with serotype B-C isolates had no history of any travel to California, and were long-time residents of Oklahoma. All 28 soil isolates of C. neformans from Oklahoma in this study were serotype A-D. Since serotype B-C recovery from a soil sample has never been reported, attempts are in progress to isolate serotype B-C from the environments of these patients from Oklahoma.

Adult↗

PubMed1986

Structural studies on teichoic acids in cell walls of several serotypes of Listeria monocytogenes.

Structural studies were carried out on the teichoic acids in cell walls of Listeria monocytogenes serotypes 3a, 4b, 4f, 6, and 7. The structure of the dephosphorylated repeating units, obtained by treatment with 46% hydrogen fluoride or alkaline hydrolysis, was examined by methylation analysis, acetolysis, and 1H-NMR spectroscopy. The results of Smith degradation of the teichoic acids and 13C-NMR spectroscopy led to the following most likely structures of the repeating units of the teichoic acids:----1-[N-acetylglucosaminyl(alpha 1----4)]ribitol-5-phosphate----for serotype 3a,----4-[galactosyl(alpha 1----6)][glucosyl(beta 1----3)]N -acetylglucosaminyl(beta 1----2)ribitol-5-phosphate----for serotype 4b,----4-[galactosyl(alpha 1----6)][N -acetylglucosaminyl(alpha 1----3)]N-acetylglucosaminyl(beta 1----2)ribitol -5-phosphate----for serotype 4f,----4-N-acetylglucosaminyl(beta 1----4)ribitol -5-phosphate----for serotype 6, and----1-ribitol-5-phosphate----for serotype 7. About 40% of the repeating units of the teichoic acid from serotype 4f were not substituted at C-3 of beta-N-acetylglucosaminyl residues.

Carbohydrate Conformation↗

PubMed2005

Neutralizing antibodies against poliovirus serotypes among children in southwest Nigeria.

In May 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by the year 2000. Despite the reported success in national immunization days, acute flaccid paralysis surveillance and accelerated efforts to meet the deadline including 'mopping-up' were executed in 1999 and subsequent years. Nigeria remains one of the major reservoirs for wild poliovirus transmission. Neutralizing antibody titre to the three poliovirus serotypes was determined among children from different communities in southwest of Nigeria, and analysed by age, gender and location. About 0.5-2 ml of blood sample was collected by venepuncture from each child. Aliquot of serum from each blood sample was inactivated prior to neutralization test by the beta method for poliovirus antibodies. A total of 347 (59.6 per cent) out of 500 and 82 children enrolled for the study had at least antibody titre of 1:8 against each of the three poliovirus serotypes. Immunity level to the three poliovirus serotypes increased with age and peaked in children aged 4-6 years. Seven (53.8 per cent) out of 13 unvaccinated children tested in the study had detectable neutralizing antibody to the three serotypes. Immunity pattern of P2 > P1 and P3 was observed but no correlation between gender and antibody to the poliovirus serotypes. The populations had 59.6 per cent herd immunity for the three poliovirus serotypes. In a country with high incidence of poliomyelitis this situation leaves a high number of non-immunized children at the risk of infection with one or more poliovirus serotypes.

Antibodies, Viral↗

PubMed2002

Different serotypes of endotoxin (lipopolysaccharide) cause different increases in albumin extravasation in rats.

Endotoxin (lipopolysaccharide [LPS] from cell membranes of gram-negative bacteria) is frequently used in experimental models of septic shock that are characterised by hypotension, peripheral vasodilation, and edema formation, as well as greatly enhanced flux of macromolecules and fluid from plasma to tissues. The edema formation and increased albumin extravasation (Ealb) could be caused by increased permeability and/or increased capillary net filtration pressure. We have measured interstitial fluid pressure (Pif) and Ealb after i.v. injection of two different serotypes of LPS in female Wistar Møller rats (200-250 g) in pentobarbital anaesthesia. Two experimental groups and one control group were studied (n = 8 in each group). Group 1, serotype 0111:B4, received 3 mg/kg LPS, Group 2, serotype 0127:B8, received 1.5 mg/kg LPS, and controls received saline vehicle (0.4 mL). Five minutes after injection of LPS or saline vehicle, human serum albumin labelled with 125I (125I-HAS; 0.05 MBq) was injected i.v. and was followed 55 min later by 131I-HSA (0.05 MBq). Five minutes thereafter the rats were killed and tissue samples were obtained from skin, muscle, and small intestine. Ealb was estimated as the difference between the plasma equivalent distribution volumes of 125I-HSA and 131I-HSA. The pattern of extravasation between the groups was the same in all the tissues studied. Group 1 serotype (0111:B4) and controls had much lower Ealb than Group 2 serotype (0127:B8; P < 0.05). Ealb differed among the tissues both in relative and absolute numbers, being largest in the intestine and smallest in skeletal muscle. We previously demonstrated a lowering of Pif after LPS injection using serotype (0127:B8). The present results demonstrate that the same serotype of LPS also causes a significant increase of Ealb, and is therefore likely caused by the lowering of Pif.

Analysis of Variance↗

PubMed1985

Genetic relationships of the dengue virus serotypes.

Previous studies have compared RNA genomes from the different dengue virus serotypes by cDNA-RNA hybridization using dengue-1 virus- and dengue-2 virus-specific cDNA probes. These probes revealed that there is a close genetic relationship between dengue virus serotypes 1 and 4. In this communication, the cDNA-RNA hybridization results using dengue-3- and dengue-4-specific cDNA probes to determine the genetic relatedness of all four dengue virus serotypes are reported. The results indicate that serotypes 1 and 4 are genetically very closely related (sharing about 70% of their genomes as detected by both the dengue-1 and dengue-4 cDNA probes), as are serotypes 3 and 4 (sharing about 50% of their genomes as detected by both the dengue-3 and dengue-4 cDNA probes). Serotype 2 does not seem to be very closely related to the other dengue virus serotypes by cDNA-RNA hybridization analysis.

Base Sequence↗

PubMed1991

Proliferative responses of T cells primed against human rhinovirus to other rhinovirus serotypes.

Lymphocytes from mice immunized with human rhinovirus (HRV) serotypes 1A or 15 proliferated in vitro in response to HRV and the activated cells were shown to be helper T (Th) cells. Lymphocytes from mice primed with HRV-1A responded to seven of eight heterologous virus serotypes, the responses to other minor cell receptor group viruses being greater than to those belonging to the major cell receptor group. A similar bias was seen with cells from mice primed with HRV-15 in that they responded preferentially to other major receptor group viruses. This pattern of cross-serotype recognition was shown to be similar in three inbred mouse strains and was not dependent upon the major histocompatibility complex haplotype. These results have revealed that there are determinants within the viral proteins of a number of serotypes of HRV that are recognized by Th cells primed against a single HRV serotype. Thus, at the level of Th cell recognition of HRV, a cross-serotype reactivity is seen which is not reflected in the B cell antibody response to virus, which is generally highly serotype-specific.

Animals↗

PubMed2000

Chimeras in noncoding regions between serotypes I and II of segment A of infectious bursal disease virus are viable and show pathogenic phenotype in chickens.

Two serotypes, I and II, have been identified for infectious bursal disease virus (IBDV), a member of the family BIRNAVIRIDAE: Here, the generation by reverse genetics of IBDV chimeras in segment A of the bisegmented genome is reported. The 5- and 3'-noncoding regions (NCRs) of a serotype II strain were exchanged with the NCRs of a full-length cDNA clone of segment A of a serotype I strain. Isolated chimeric viruses were characterized in cell culture and susceptible chickens. The results show that IBDV chimeras in segment A were able to replicate in cell culture and that VP1 encoded by a serotype I segment B is functionally active with serotype I NCRs as well as with serotype II NCRs. Chimeric viruses infected susceptible chickens and caused mild depletion of bursal cells. Thus, the noncoding regions of segment A are not responsible for the different pathotypes of IBDV serotypes I and II.

Animals↗

PubMed2002

Genetic clustering of all 102 human rhinovirus prototype strains: serotype 87 is close to human enterovirus 70.

Human rhinoviruses (HRV), common agents of respiratory infections, comprise 102 designated serotypes. The genetic relationships of HRV prototype strains and the possibility of using genetic identification of a given HRV field strain were studied. Genomic sequences in the VP4/VP2 region were obtained from all 102 prototype strains. Phylogenetic analysis included 61 recently isolated Finnish field strains. Seventy-six out of the 102 prototype strains clustered in the HRV genetic group A and 25 in group B. Serotype 87 clustered separately and together with human enterovirus 70. The 'percentage' interserotypic differences were generally similar to those between different enterovirus serotypes, but for six pairs of HRV serotypes they were less than 10%. The maximum variation in genetic group A was 41% at the nucleotide level and 28% at the amino acid level, and in genetic group B 34% and 20%, respectively. Judging from the observed interserotypic differences, the 61 Finnish field isolates might represent as many as 19 different serotypes. One cluster of the field strains did not directly associate with any of the prototype strains and might represent a new serotype. However, larger numbers of field isolates of known serotype need to be characterized, possibly also in the VP1 region, to evaluate the feasibility of genetic typing of HRV strains.

Capsid↗