Withdrawal of rotavirus vaccine recommendation. (49/2332)

In July 1999, CDC recommended that health-care providers and parents postpone use of the rhesus rotavirus vaccine-tetravalent (RRV-TV) (RotaShield, Wyeth Laboratories, Inc., Marietta, Pennsylvania), for infants, at least until November 1999. This action was based on reports to the Vaccine Adverse Event Reporting System of intussusception (a type of bowel obstruction that occurs when the bowel folds in on itself) among 15 infants who received rotavirus vaccine. Also at that time, the manufacturer, in consultation with the Food and Drug Administration, voluntarily ceased further distribution of the vaccine.  (+info)

Comparative studies of human rotavirus serotype G8 strains recovered in South Africa and the United Kingdom. (50/2332)

Epidemiological studies on the VP7 serotype prevalence of human rotaviruses in South Africa and the United Kingdom identified several strains which could not be serotyped as G1-G4 by monoclonal antibodies. Further analysis of these strains with a G8-specific monoclonal antibody and with probes for human rotaviruses confirmed them as G8 rotaviruses. These G8 strains exhibited a high degree of sequence identity when compared with each other and with other rotavirus G8 strains. Five South African strains were further characterized as VP6 subgroup I, but with a long RNA electropherotype, which is similar to the G8 strains previously isolated in Finland. In the UK strains, one was VP6 subgroup II with a long RNA electropherotype (similar to the Italian G8 strain). The other two were subgroup I with a short RNA electropherotype. None of these strains exhibited the super-short RNA electropherotype described in the prototype G8 strains recovered from Indonesia (69M).  (+info)

Molecular detection of Norwalk-like caliciviruses in sewage. (51/2332)

In this study, Norwalk-like virus (NLV) RNA was detected by reverse transcriptase PCR (RT-PCR) in sewage water concentrates. Sequence analysis of the RT-PCR products revealed identical sequences in stools of patients and related sewage samples. In 6 of 11 outbreak-unrelated follow-up samples, multiple NLV genotypes were present. Levels as high as 10(7) RNA-containing particles per liter were found. These data show that high loads of NLVs may be present in sewage and warrant further studies addressing the efficacy of NLV removal by sewage water treatment processes.  (+info)

Integrins alpha2beta1 and alpha4beta1 can mediate SA11 rotavirus attachment and entry into cells. (52/2332)

Most mammalian rotaviruses contain tripeptide amino acid sequences in outer capsid proteins VP4 and VP7 which have been shown to act as ligands for integrins alpha2beta1 and alpha4beta1. Peptides containing these sequences and monoclonal antibodies directed to these integrins block rotavirus infection of cells. Here we report that SA11 rotavirus binding to and infection of K562 cells expressing alpha2beta1 or alpha4beta1 integrins via transfection is increased over virus binding to and infection of cells transfected with alpha3 integrin or parent cells. The increased binding and growth were specifically blocked by a monoclonal antibody to the transfected integrin subunit but not by irrelevant antibodies. In our experiments, integrin activation with phorbol ester did not affect virus binding to cells. However, phorbol ester treatment of K562 parent and transfected cells induced endogenous gene expression of alpha2beta1 integrin, which was detectable by flow cytometry 16 h after treatment and quantitatively correlated with the increased level of SA11 virus growth observed after this time. Virus binding to K562 cells treated with phorbol ester 24 h previously and expressing alpha2beta1 was elevated over binding to control cells and was specifically blocked by the anti-alpha2 monoclonal antibody AK7. Virus growth in alpha4-transfected K562 cells which had also been induced to express alpha2beta1 integrin with phorbol ester occurred at a level approaching that in the permissive MA104 cell line. We therefore have demonstrated that two integrins, alpha2beta1 and alpha4beta1, are capable of acting as cellular receptors for SA11 rotavirus.  (+info)

Rotavirus open cores catalyze 5'-capping and methylation of exogenous RNA: evidence that VP3 is a methyltransferase. (53/2332)

Rotavirus open cores prepared from purified virions consist of three proteins: the RNA-dependent RNA polymerase, VP1; the core shell protein, VP2; and the guanylyltransferase, VP3. In addition to RNA polymerase activity, open cores have been shown to contain a nonspecific guanylyltransferase activity that caps viral and nonviral RNAs in vitro. In this study, we examined the structure of RNA caps made by open cores and have analyzed open cores for other capping-related enzymatic activities. Utilizing RNase digestion and thin-layer chromatography, we found that the majority ( approximately 70%) of caps made by open cores contain the tetraphosphate linkage, GppppG, rather than the triphosphate linkage, GpppG, found on mRNAs made by rotavirus double-layered particles. Enzymatic analysis indicated that the GppppG caps resulted from the lack of a functional RNA 5'-triphosphatase in open cores, to remove the gamma-phosphate from the RNA prior to capping. RNA 5'-triphosphatases commonly exhibit an associated nucleoside triphosphatase activity, and this too was not detected in open cores. Caps of some RNAs contained an extra GMP moiety (underlined) and had the structure 3'-GpGp(p)ppGpGpC-RNA-3'. The origin of the extra GMP is not known but may reflect the cap serving as a primer for RNA synthesis. Methylated caps were produced in the presence of the substrate, S-adenosyl-l-methionine (SAM), indicating that open cores contain methyltransferase activity. UV cross-linking showed that VP3 specifically binds SAM. Combined with the results of earlier studies, our results suggest that the viral guanylyltransferase and methyltransferase are both components of VP3 and, therefore, that VP3 is a multifunctional capping enzyme.  (+info)

Neutralization assay for human group C rotaviruses using a reverse passive hemagglutination test for endpoint determination. (54/2332)

A novel neutralization assay for human group C rotavirus (CHRV) was developed by using a reverse passive hemagglutination (RPHA) test for endpoint determination. In this assay, the neutralization (N)-RPHA test, serial twofold dilutions of sera were mixed with a solution of CHRV that yielded an RPHA test titer of 8 at 3 days after infection. The mixtures were incubated at 37 degrees C for 1 h and were inoculated onto CaCo-2 cell monolayers in a 96-well microplate. Maintenance medium containing 100 microgram of pancreatin per ml was placed in each well. The plate was sealed with sticky plastic film and was incubated at 37 degrees C for 3 days under continuous rotation. Then, the RPHA test titer of each well was determined. The neutralization titer was expressed as the reciprocal of the maximum dilution of the serum that exhibited a fourfold (75%) or greater reduction in the RPHA test titer (8 to 2 or less). Seroconversion of neutralizing antibody was demonstrated by this method in four sets of paired serum specimens from patients with diarrheal disease caused by CHRV. The seroprevalence of CHRV in the general population in Okayama Prefecture was 26.8% by immunofluorescence and 25.5% by the N-RPHA test. The N-RPHA test described here is the first system used to assay for a neutralization antibody against CHRV and is applicable in both clinical and epidemiological settings.  (+info)

VP7 and VP4 genotyping of human group A rotavirus in Buenos Aires, Argentina. (55/2332)

Specific and sensitive tests for the detection and typing of group A rotavirus strains are needed for a more comprehensive knowledge of the epidemiology of rotaviral infection. In this study 500 stool specimens taken from 1996 to 1998 from children with acute diarrhea in Buenos Aires were examined. Group A rotavirus was unequivocally demonstrated in 62% of the samples tested by enzyme-linked immunosorbent assay (ELISA) for detection of VP6 antigen, polyacrylamide gel electrophoresis of double-stranded RNA, and reverse transcription-PCR (RT-PCR) for amplification of the VP7:G (1, 062 bp) and VP4:P (876 bp) genes. Only five positive specimens were found by RT-PCR but not by ELISA. G and P typing was carried out by nested amplification of variable sequences of the VP7 and the VP4 genes with six G- and five P-type-specific primers (multiplex PCR). Results obtained by this method showed the prevalence of the following G and P types: G1, 39%; G2, 43%; G4, 4%; P[8], 16%; P[4], 71%. Unexpectedly, the G-P type combination most frequently found was G2P[4] (43%) rather than G1P[8] (12%), which is the most commonly found worldwide. Unusual strains of the type G1P[4] accounted for 14% of the total, while mixed infections with more than one type were found in 10% of the samples. Detection of fecal rotavirus-specific immunoglobulin M (IgM) and IgA antibodies in consecutive samples of two patients taken at daily intervals demonstrated that high levels of IgM and IgA antibodies were detected on day 1 after the onset of disease and that the samples remained positive for about 10 days, after which virus shedding was no longer observed. Multiplex PCR offers a sensitive and specific alternative to determine the prevalence of group A rotavirus G and P types and to identify the emergence of uncommon strains, whereas detection of fecal IgM and IgA antibodies represents a useful supplement to virus detection for the diagnosis of current or recently acquired infections.  (+info)

Genotype profiles of rotavirus strains from children in a suburban community in Guinea-Bissau, Western Africa. (56/2332)

The P (VP4) and G (VP7) genotypes of 167 group A rotavirus strains obtained during the period 1996 to 1998 from 149 children living in a suburban community in Guinea-Bissau, western Africa, were determined by the reverse transcription-PCR technique. A total of nine combinations including five different P types and five different G types were identified. The globally common genotype pairs P[8], G1; P[4], G2; P[8], G3 and P[8], G4 were underrepresented in this study area. We found a substantial year-to-year variation in the occurrence of the genotype combinations. In 1996 and 1997, P[6], G2 was the most frequent, whereas P[8], G1 was more common in 1998. The unusual type P[9], G3 and a few mixed infections were detected. Sixteen percent of the rotavirus-positive samples were nontypeable.  (+info)