Comparative Analysis of Infants' Response to Newly Included Indian Rotavirus Vaccines

Neutralizing virus infectivity is considered a primary immunological defense against rotavirus infection. In India, the National Immunization Programme includes RR [monovalentlive attenuated rotavirusvaccinethat contains a human RV G1P strain]and RT [pentavalent bovine-human reassortant vaccine containing five human-bovine reassortant strains ( G1, G2, G3, G4, and P[8])], as well as two newer vaccines: RV [a monovalent vaccine developed from neonatal bovine-human reassortant strain 116E, G9P] and RS [a thermostable bovine-human reassortant multivalent vaccine (G1, G2, G3, G4, G9)]. The objective of astudy was to compare the neutralizing antibody (NAbs) responses against the most common rotavirus types (G1-G4, G9, and G12) in infants vaccinated with RV and RS.

The study entailed collection of convalescent serum samples from healthy infants vaccinated with either RV and RS. Nabtiters against reference human rotavirus strains (G1P[8], G2P[4], G3P[8], G4P[6], G9P[8], and G12P[11]) were determined.

It was noted thatRS-vaccinated infants, the geometric mean titers (GMTs) of NAbs against homotypic strains were significantly higher than those against heterotypic strains. NAbs against RV strains G1P[8] and G9P[8] were significantly higher compared to G3P[8], G2P[4], and G4P[6]. Only 30.5% of infants showed serum cross-NAbs to the fully heterotypic G12P[11] strain. For RV, 80.6% of recipients seroconverted to the partial homotypic G9P[8] strain, and 77.4% were seropositive against the heterotypic G1P[8] strain. Lower heterotypic responses were observed for RV G2P[4], G3P[8], and G4P[6] strains. Further, only 35.48% of sera cross-neutralized the partial heterotypic G12P[11] strain. Comparative analysis revealed significantly higher serum NAbs against G1P[8], G3P[8], G4P[6], and G9P[8] in the RS group compared to the RV group.

The findings indicated that the multivalent RS vaccine may provide broader protection against common rotaviruses. Meanwhile, bothRV and RS vaccines showed relatively low cross-neutralization against the G12P[11] strain––highlighting the need to include the G12 component in future rotavirus vaccines.

The results provide important insights into the homotypic and heterotypic responses among rotavirus-vaccinated children in India. It demonstrates that a multivalent vaccine like RS may offer broader coverage against common rotavirus types. 

Source: Ranshing SS, Walimbe AM, Bavdekar AR, et al. Available at SSRN 4793116.