EFFICACY OF RHESUS ROTAVIRUS VACCINE MMU-18006 AGAINST GASTROENTERITIS DUE TO SEROTYPE-1 ROTAVIRUS

We conducted a clinical trial of rhesus rotavirus vaccine MMU-18006 (R RV, serotype 3) to assess the immunogenicity, transmissibility and boo ster effect of this vaccine in a welfare nursery in Sapporo, from Sept ember 1986 to October 1988. After the trial, in March 1989, an outbrea k of gastroenteritis due to a wild strain of serotype 1 rotavirus (RV- 1) occurred in the study population. Infants were divided into three g roups based on vaccination history: five booster vaccinees, 18 one-dos e vaccinees and 18 control infants who did not receive vaccine. There was a significant relationship between asymptomatic infection and high er levels of preoutbreak antibody titres against KU (serotype 1) but n ot RRV. Significant protection front rotavirus illness was observed bo th in the booster vaccine group and in the one-dose vaccine group but not the control group. Rotavirus-specific serum IgA immune response wa s considered to be one of the indicators of recent rotavirus infection , and did not correlate with resistance to rotavirus illness. Our resu lts revealed that protection from rotavirus illness was serotype-speci fic and that previous rotavirus infection, including vaccination, was important to induce the heterotypic immune response, and that ageing o r booster inoculation of RRV might play a role in the protection again st serotype 1 rotavirus infection. From our findings, a booster admini stration was thought to be important to induce effective heterotypic i mmunity and should be included in a future rotavirus vaccine trial to obtain sufficient protection against four major serotypes of rotavirus .