Rotavirus-neutralizing Antibodies Research Articles

Rotavirus-neutralizing antibodies inhibit virus binding to integrins α2β1 and α4β1

Rotavirus outer capsid proteins VP5(*), VP8(*) and VP7 elicit neutralizing, protective antibodies. The alpha 2 beta 1 integrin is a cellular receptor for rotavirus that is bound by VP5(*). Some rotaviruses also recognize the alpha 4 beta 1 integrin. In this study, the effects of antibodies to rotavirus on virus binding to recombinant alpha 2 beta 1 and alpha 4 beta 1 expressed on K562 cells were determined. All neutralizing monoclonal antibodies to VP5(*) tested (YO-2C2, 2G4, 1A10) and two to VP7 (RV-3:2, RV-4:2) inhibited rotavirus binding to alpha 2 beta 1. Rotavirus binding to alpha 4 beta 1 was reduced by 2G4 and neutralizing antibody F45:2, directed to VP7. However, a neutralizing antibody to VP8(*) (RV-5:2) and one to VP7 (RV-3:1) did not affect rotavirus binding to these integrins. Virus-cell binding was unaffected by non-neutralizing antibody RVA to the rotavirus inner capsid protein VP6. The attachment of human rotavirus strain Wa to these integrins was inhibited by infection sera with neutralizing activity collected from two children hospitalised with severe rotavirus gastroenteritis. A negative reference serum did not affect rotavirus-cell attachment. As the binding of rotaviruses to alpha 2 beta 1 and alpha 4 beta 1 is inhibited by neutralizing antibodies to VP5(*) and VP7, and serum from children with rotavirus disease, rotavirus recognition of these integrins may be important for host infection.

Vaccination of Thai infants with rhesus-human reassortant tetravalent oral rotavirus vaccine

In a randomized double blind placebo-controlled study, the rhesus-human reassortant tetravalent oral rotavirus vaccine (dose 4 x 10(4) plaque-forming units) was evaluated in Thai infants immunized at ages 2, 4 and 6 months. To investigate dose responses and to compare vaccine-induced and naturally acquired rotavirus immunity in the study population blood specimens were collected before and 1 month after each vaccination and at 12 months of age. No adverse reactions attributable to the vaccine were detected in the vaccinees. Sixty-three of 94 (67%) vaccine recipients showed a seroconversion in rotavirus IgA enzyme-linked immunosorbent assay antibodies after one or more doses, whereas only 15 of 93 (16%) placebo-vaccinated control children showed an IgA enzyme-linked immunosorbent assay antibody response, suggestive of natural rotavirus infection, between 2 and 7 months of age. By measuring rhesus rotavirus-neutralizing antibodies a seroconversion was detected in 49% of the vaccinees and 14% of the controls between 2 and 7 months of age. The geometric mean titers of neutralizing antibodies to human rotavirus serotypes 1, 2, 3 and 4 after the completion of vaccinations and at 12 months of age were higher in the vaccinees than in the controls. It is concluded that, even though maternally acquired rotavirus antibodies are commonly present, the rhesus-human reassortant tetravalent vaccine is immunogenic in many Thai infants ages 2 to 6 months. The immunogenicity of this vaccine is enhanced by multiple doses.

Measurement of rotavirus-neutralizing coproantibody in children by fluorescent focus reduction assay

A fluorescent focus reduction assay suitable for the measurement of rotavirus-neutralizing antibodies in the feces of children was developed. Of 408 stools tested, 7% showed false-positive neutralization, and the number of rotavirus serotypes neutralized by a fecal extract was proportional to the levels of antirotaviral immunoglobulin A in the extract.

Comparison of rotavirus immunoglobulin A coproconversion with other indices of rotavirus infection in a longitudinal study in childhood

In order to determine the sensitivity and reliability of antirotaviral fecal immunoglobulin A (IgA) as an indicator of rotavirus reinfection, the antibody responses to rotavirus of 44 infants with severe rotavirus gastroenteritis recruited on admission to a hospital were studied. Feces were collected daily during hospitalization and weekly thereafter, and sera were obtained every 4 months, for 6 to 32 months (median, 17 months). Antirotaviral IgG, IgA, and IgM were measured by enzyme immunoassay in all samples. Rotavirus antigen, rotavirus-neutralizing antibody, and total IgA were measured in feces. The results showed that use of an IgA index (ratio of specific IgA to total IgA) was unnecessary to identify copro-IgA conversion to rotavirus. The other markers of rotavirus infection tested showed a high level of predictive accuracy of coproconversion in rotavirus-neutralizing antibody. Copro-IgM, serum IgM, and virus in feces were insensitive measures of neutralizing antibody coproconversion. Seroconversion in IgG or IgA was detected in 46% of neutralizing coproconversions. The most sensitive marker, present in 92% of neutralizing coproconversions, was antirotaviral fecal IgA conversion. This correlation of fecal IgA with fecal neutralizing antibody suggests that coproconversions in IgA represent true elevations in antirotaviral IgA with neutralizing capacity. A coproconversion in IgA appears to indicate genuine rotavirus infection. Copro-IgA conversions in feces collected weekly are likely to be more sensitive markers of rotavirus reinfection than are seroconversion and virus detection combined in epidemiological studies of acute diarrhea in children and in rotavirus vaccine trials.

Noninfectious rotavirus (strain RRV) induces an immune response in mice which protects against rotavirus challenge

We found that female adult mice parenterally inoculated with noninfectious rotavirus (simian strain RRV) developed virus-specific neutralizing antibodies in the serum; newborn mice from these dams were protected against RRV-induced gastroenteritis. In addition, mice parenterally inoculated with noninfectious RRV developed virus-specific cytotoxic T-lymphocyte precursors in the spleen. Replication of rotavirus in intestinal epithelial cells was apparently not required to induce rotavirus-neutralizing antibodies or rotavirus-specific cytotoxic T lymphocytes. Parenteral immunization of infants and young children with noninfectious rotaviruses may induce an immune response which protects against rotavirus challenge.

Influence of immunomodulatory agents on bovine humoral and cellular immune responses to parenteral inoculation with bovine rotavirus vaccines

Sodium diethyldithiocarbamate (DTC), mycobacterium cell wall extract (MCWE, Regressin TM), killed Corynebacterium parvum ( C. parvum, Immunoregulin TM) and muramyldipeptide (MDP) were each combined with purified, live bovine rotavirus and inoculated into 3 month-old Holstein-Friesian calves in order to examine their ability to potentiate specific humoral and cellular immune responses. The vaccinated calves were boosted twice at 3 and 6 weeks after initial vaccine inoculation. The rotavirus was administered intramuscularly either in an aqueous suspension or in a water-in-oil (WIO) emulsion, prepared with incomplete Freund's adjuvant (IFA). DTC and C. parvum were given by the intravenous route, while MCWE and MDP were incorporated directly in the rotavirus suspension. Two groups of calves were also vaccinated either with rotavirus and IFA or with rotavirus emulsified in mineral oil and a mannide oleate compound (MOC, Montanide 888 TM). A control group of calves was given phosphate-buffered saline (PBS) solution emulsified with IFA. The different vaccine preparations were then compared by studying the kinetics of serum rotavirus-neutralizing antibody production and of proliferative response by blood lymphocytes following in vitro stimulation with bovine rotavirus. The results showed that: (1) the bovine rotavirus should be incorporated in a WIO emulsion in order to induce a cell-mediated immune response as detected by the rotavirus-specific in vitro stimulation test with blood lymphocytes, and to produce higher neutralizing antibody titers in the serum; (2) the vaccines prepared with the mineral oil-MOC complex or IFA both induced comparable levels of humoral and cellular immune responses. The use of mineral oil and MOC as adjuvant may be preferred to IFA, because of the facility of preparing the vaccine and of the low viscosity of the resulting WIO emulsion: (3) the addition of MDP to the WIO emulsion prepared with IFA resulted in a higher cell-mediated immune response as determined by the in vitro blood lymphocyte transformation index specific for bovine rotavirus.