ROTAVIRUS VACCINES - AN OVERVIEW

Rotavirus vaccine development has focused on the delivery of live atte nuated rotavirus strains by the oral route. The initial ''Jennerian'' approach involving bovine (RIT4237, WC3) or rhesus (RRV) rotavirus vac cine candidates showed that these vaccines were safe, well tolerated, and immunogenic but induced highly variable rates of protection agains t rotavirus diarrhea. The goal of a rotavirus vaccine is to prevent se vere illness that can lead to dehydration in infants and young childre n in both developed and developing countries. These studies led to the concept that a multivalent vaccine that represented each of the four epidemiologically important VP7 serotypes might be necessary to induce protection in young infants, the target population for vaccination. H uman-animal rotavirus reassortants whose gene encoding VP7 was derived from their human rotavirus parent but whose remaining genes were deri ved from the animal rotavirus parent were developed as vaccine candida tes. The greatest experience with a multivalent vaccine to date has be en gained with the quadrivalent preparation containing RRV (VP7 seroty pe 3) and human-RRV reassortants of VP7 serotype 1, 2, and 4 specifici ty. Preliminary efficacy trial results in the United States have been promising, whereas a study in Peru has shown only limited protection. Human-bovine reassortant vaccines, including a candidate that contains the VP4 gene of a human rotavirus (VP4 serotype 1A), are also being s tudied.