Neutralizing antibody (NAb) responses to different rotavirus serotypes were compared in 64 convalescentphase serum samples from hospitalized rotavirus-positive children less than 2 years of age and their mothers. Compared to the child patients, the mothers showed significantly higher NAb positivity to animal rotavirus serotypes G3 simian (96.88%), G6 bovine (85.94%), and G10 bovine (25.0%) and to human rotavirus serotypes G8 (79.69%) and G3 (57.81%) (P < 0.01 for each) but not to human serotypes G1, G2, G4, and G9 (P > 0.05). The overall prevalence of NAb among the child patients was low for human rotavirus serotypes G1 (20.31%) and G3 (21.8%). The comparative NAb response in individual mother-child paired serum samples was analyzed against each rotavirus serotype. A substantial number of child patients showed higher NAb titers than their mothers to serotypes G1, G2, G4, and G9, indicating that these serotypes are the major serotypes causing rotavirus diarrhea among the children of Pune, India. In these cases, the mothers were either negative or had lower titers of NAbs than their children. Correlation was observed between the infecting serotype and child patient serum that showed a homologous NAb response at a higher level than that of the mother. It appears that when the level of NAb to a particular serotype is higher among child patients than among their mothers, that serotype is the infecting serotype, and that low titers of NAb among the mothers predispose the children to infection with that serotype, if the serotype is in circulation.

Rotavirus specific immunoglobulin levels were estimated and compared between mothers undergoing delivery from two socio-economic groups (n = 56 each) by direct/capture ELISA. IgG geometric mean titers (GMTs) of cord blood/mothers serum at delivery were significantly higher in the higher socio-economic group (HSG) as compared to the lower socio-economic group (LSG) (P < 0.01). Thirty-four mother-infant pairs (17 from each group) were followed-up up to 6 months for the occurrence of rotavirus infections. All follow-up LSG infants were low birth weight as against none from the HSG. Detection of virus by ELISA/RT-PCR and considering IgM/IgA seroconversion as an index of infection, 11 and 17 infants from HSG and LSG respectively had rotavirus infections. Two infants from LSG were hospitalized for severe rotavirus diarrhea but none from the HSG. Lower IgG levels in the LSG mother-infant pairs as compared to those of HSG, suggests a possible role of under nutrition in development of antibodies and immunity. Infants from the HSG who did not have rotavirus infections had significantly higher IgG GMTs in cord blood and serum samples at 6 months, than those HSG infants who had symptomatic/asymptomatic rotavirus infections (P < 0.05). In conclusion, fewer rotavirus infections occur when cord blood contains higher level of IgG antibodies, suggesting a role of protective immunity.

Rotavirus specific, serum IgM/IgA/IgG levels among hospitalized children and their respective mothers were determined. Children were grouped as having rotavirus diarrhoea (RVD) and non-rotavirus diarrhoea (NRVD) on the basis of fecal excretion measured by ELISA and RT-PCR. Although IgM seropositivity was observed among children of both the groups, it was significantly higher in the acute as well as convalescent phase serum samples (P < 0.05 for both) of RVD group. Five out of ten acute sera from the NRVD group were positive for IgM and seven showed IgA/IgG seroconversion indicating rotavirus infection among these children in the past. It was noted that, three out of 24 mothers' sera from RVD group, showed presence of IgM in the serum collected during convalescence of their children. The observation suggests, subclinical rotavirus infection among mothers probably contacted from their children. This is supported by the seroconversion for IgA/IgG among these three mothers. Such a phenomenon was not noticed among the mothers from NRVD group. In general, IgA positivity did not vary significantly among the children from both the groups. IgA seropositivity was significantly higher (P < 0.001) from children of RVD group as compared to healthy group of children following rotavirus infection. From RVD group, all the child patients and 12 mothers out of 24 (50%) showed IgA/IgG seroconversion. None of the mothers from NRVD group showed seroconversion. Serum samples of healthy children and adults, showed IgM positivity at equal level (10%), but a significant difference (P < 0.01) was observed in IgA positivity. In conclusion, subclinical transmission of rotavirus infection from children to their mothers may occur. Seroconversion alone cannot be considered as a marker of rotavirus diarrhoea in children. Moreover, about 40-50% of subjects lacked rotavirus specific IgA at protective levels, making them susceptible to rotavirus infection.

An epidemic of diarrhoea in Jawhar, a tribal area of Thane district, Maharashtra, India was investigated. Within a period of approximately 2 months 490 cases of acute diarrhoea were reported among children under 5 years of age, with a case fatality rate of 0.40%. Twenty-seven out of 39 (69.23%) rectal swabs/faecal specimens obtained from hospitalized paediatric patients up to 2 years of age from Jawhar were positive by ELISA for rotavirus. Of these, seven were in the age group of < or = 6 months. Seven ELISA-positive faecal specimens were positive for serotype G3 by RT PCR. Out of 15 serum samples collected from these patients, 12 showed the presence of rotavirus-specific IgM. Rotavirus appears to be the aetiological agent of this widespread outbreak in Jawhar, Thane district, Maharashtra state, India.