Rotaviruses detected by reverse transcription polymerase chain reaction in acute gastroenteritis during a trial of rhesus-human reassortant rotavirus tetravalent vaccine: implications for vaccine efficacy analysis.

Abstract

Rotaviruses are routinely diagnosed by detection of rotavirus antigen in stools using an enzyme immunoassay (EIA). A sensitive method, like reverse transcription polymerase chain reaction (RT-PCR), may reveal more rotaviruses, but the clinical significance of such findings is not well established. To study whether RT-PCR can detect more episodes of rotavirus-associated gastroenteritis than EIA and to determine how rotavirus RT-PCR findings might change efficacy analysis of a rotavirus vaccine trial, in which the outcome measure was rotavirus gastroenteritis diagnosis with EIA. We applied RT-PCR for detection of rotaviruses in gastroenteritis episodes encountered in an efficacy trial of rhesus-human reassortant rotavirus tetravalent (RRV-TV) vaccine, in a total of 2398 infants. During a follow-up, covering two rotavirus epidemic seasons, 256 cases of rotavirus associated gastroenteritis were detected by EIA; 226 were in the primary efficacy analysis period that included children who had received three doses of vaccine or placebo. With RT-PCR, 84 (33%) more cases of rotavirus gastroenteritis were diagnosed than with EIA, 65 of these were in the primary efficacy analysis period. Clinically, cases of rotavirus gastroenteritis diagnosed by RT-PCR were much milder (median severity score 6 on a 20-point scale) than those diagnosed by EIA (median score 11), P < 0.0001. RT-PCR revealed proportionally more G2 and G4 rotaviruses than EIA. G1 rotaviruses detected by RT-PCR were almost equally divided between RRV-TV (25) vaccine and placebo (28) groups, whereas an apparent vaccine protective effect was seen in the distribution of G2 (one in the RRV-TV and eight in the placebo group) and G4 rotaviruses (six in the RRV-TV and 14 in the placebo group). RT-PCR is a useful tool in the diagnosis of rotavirus gastroenteritis, particularly for cases associated with other than the epidemiologically dominant G-type. Application of RT-PCR contributes to the overall appraisal of performance of rotavirus vaccine.