Immune response to three doses of quadrivalent rotavirus vaccine: 1-year follow-up

The VP6 protein of rotavirus interacts with a large fraction of human naive B cells via surface immunoglobulins

Immunity to human group A rotavirus (RV), a major cause of viral gastroenteritis in infants, involves B lymphocytes that provide RV-specific antibodies. Additionally, some arguments suggest that naive B cells could be implicated in the first steps of the immune response against RV. The aim of our study was to analyze the interaction of VP6 and VP7 RV capsid proteins with human B cells depending on the immune status of the individual, i.e., naive or RV experienced. For this purpose, a two-color virus-like particle flow cytometry assay was devised to evaluate the blood B-lymphocyte reactivity to VP6 and VP7 proteins from healthy RV-exposed adults, recently infected infants, and neonates at birth. Both VP6 and VP7 interactions with B cells were mediated by surface immunoglobulins and probably by their Fab portions. VP7-reactive B lymphocytes were mainly detected from RV-experienced patients and almost exclusively in the CD27-positive memory cell fraction. Conversely, VP6-reactive B lymphocytes were detected at similar and high frequencies in adult, infant, and neonate samples. In adult samples, VP6 reacted with about 2% of the CD27-negative (CD27(neg)) naive B cells. These results demonstrated that the VP6 RV protein interacted with a large fraction of naive B lymphocytes from both adults and neonates. We propose that naive B cell-VP6 interaction might influence the strength and quality of the acquired immune response and should be considered for elaborating RV vaccine strategies.

The role of serum antibodies in the protection against rotavirus disease: an overview

A critical observation in understanding immunity to rotavirus is that children infected with wild virus or vaccinated with oral live vaccines develop a humoral immune response and are protected against severe disease upon reinfection. Nevertheless, much controversy exists as to whether these serum antibodies are directly involved in protection or merely reflect recent infection, leaving the protective role to mucosal or cell-mediated immunity or to other as-yet-undefined mechanisms. We have reviewed data from a variety of studies in humans, including challenge experiments in adult volunteers, longitudinal studies of rotavirus infection in young children, and clinical trials of animal and animal-human reassortant rotavirus vaccines in infants. These data suggest that serum antibodies, if present at critical levels, are either protective themselves or are an important and powerful correlate of protection against rotavirus disease, even though other host effectors may play an important role as well.

Rhesus rotavirus-based quadrivalent vaccine is efficacious despite age, socioeconomic conditions and seasonality in Venezuela

This report describes the results of additional analyses of the trial carried out with the rhesus rotavirus-based quadrivalent vaccine in Venezuela. In the present study, we re-examined the data from this previous rotavirus vaccine trial to assess the statistical interaction between vaccine efficacy and (i) the duration of efficacy into the second year of life, (ii) socioeconomic conditions, and (iii) rotavirus seasonality. We found that among Venezuelan children, the rotavirus vaccine confers protection against severe diarrhea during the first 2 years of life independently of socioeconomic conditions and seasonality.