Vitamin A Deficiency Impairs Adaptive B and T Cell Responses to a Prototype Monovalent Attenuated Human Rotavirus Vaccine and Virulent Human Rotavirus Challenge in a Gnotobiotic Piglet Model

Kuldeep S Chattha,Linda J Saif,Sukumar Kandasamy,Anastasia N Vlasova,Ding Xiang Liu

doi:10.1371/journal.pone.0082966

Abstract

Rotaviruses (RV) are a major cause of gastroenteritis in children. Widespread vitamin A deficiency is associated with reduced efficacy of vaccines and higher incidence of diarrheal infections in children in developing countries. We established a vitamin A deficient (VAD) gnotobiotic piglet model that mimics subclinical vitamin A deficiency in children to study its effects on an oral human rotavirus (HRV) vaccine and virulent HRV challenge. Piglets derived from VAD and vitamin A sufficient (VAS) sows were orally vaccinated with attenuated HRV or mock, with/without supplemental vitamin A and challenged with virulent HRV. Unvaccinated VAD control piglets had significantly lower hepatic vitamin A, higher severity and duration of diarrhea and HRV fecal shedding post-challenge as compared to VAS control pigs. Reduced protection coincided with significantly higher innate (IFNα) cytokine and CD8 T cell frequencies in the blood and intestinal tissues, higher pro-inflammatory (IL12) and 2-3 fold lower anti-inflammatory (IL10) cytokines, in VAD compared to VAS control pigs. Vaccinated VAD pigs had higher diarrhea severity scores compared to vaccinated VAS pigs, which coincided with lower serum IgA HRV antibody titers and significantly lower intestinal IgA antibody secreting cells post-challenge in the former groups suggesting lower anamnestic responses. A trend for higher serum HRV IgG antibodies was observed in VAD vs VAS vaccinated groups post-challenge. The vaccinated VAD (non-vitamin A supplemented) pigs had significantly higher serum IL12 (PID2) and IFNγ (PID6) compared to vaccinated VAS groups suggesting higher Th1 responses in VAD conditions. Furthermore, regulatory T-cell responses were compromised in VAD pigs. Supplemental vitamin A in VAD pigs did not fully restore the dysregulated immune responses to AttHRV vaccine or moderate virulent HRV diarrhea. Our findings suggest that that VAD in children in developing countries may partially contribute to more severe rotavirus infection and lower HRV vaccine efficacy.

Highlights

Rotavirus (RV) is a leading cause of severe viral gastroenteritis in infants and young children
The area under the curve (AUC) for diarrhea severity and shedding was significantly lower in the vitamin A deficient (VAD) control groups compared to the vitamin A sufficient (VAS) control groups suggesting that vitamin A deficiency may result in more severe human rotavirus (HRV) infection and diarrhea (Table 1)
Neither of the VAD control groups were protected against HRV shedding post-challenge; supplementation of vitamin A in the control VAD group reduced fecal HRV shedding by 1 day (Figure 1A)

Summary

Introduction

Rotavirus (RV) is a leading cause of severe viral gastroenteritis in infants and young children. Biologicals]) are available, which have been recommended by the World Health Organization (WHO) to be included in the national immunization programs of all countries worldwide [2,3] These new second generation RV vaccines have improved the efficacy (~50%) against severe RV diarrhea compared to first generation vaccines (~20%) in low income countries [2]. In this study we measured the impact of VAD and supplemental vitamin A on RV vaccine and infection in a neonatal gnotobiotic pig model of human rotavirus (HRV) diarrhea. To examine the synergism between oral vitamin A supplementation (as recommended by WHO) and AttHRV vaccines and their effects on virulent HRV challenge, we established a VAD pig model, mimicking infants and children with subclinical vitamin A deficiency in developing countries

Materials and Methods

Results

Discussion