ABSTRACT
The development and introduction of rotavirus vaccines into global immunization programs has been a high priority for many international immunization agencies. Vaccine development was started with animal rotaviruses which can be distinguished from human strains on the bases of type specific surface antigens. Bovine (WC3), rhesus (RRV), and lamb (LLR) rotaviruses were the potential candidates for vaccine development. They established the efficacy of animal rotavirus vaccines in infants against severe rotavirus diarrhea, but failed to show consistent efficacy in other trials. Animal rotavirus vaccines were improved by the development of animal-human reassortant vaccines containing the attenuation properties of animal strains and individual genes encoding the outer capsid proteins of human strains. Attenuated human rotavirus vaccine development was designed based on the results of extensive studies on natural rotavirus infections conferring the protection against subsequent infections and reduction of diarrhea severity and heterotypic protections. RIX4414 was a potential candidate for attenuated human rotavirus vaccine. Two live oral rotavirus vaccines are currently licensed in many countries; Rota-Teq(MSD) combines bovine(WC3)-human reassortant strains containing five human serotypes. Rotarix(GSK) is derived from the attenuated human rotavirus strain(RIX4414). Each vaccine has proven highly effective in preventing severe rotavirus diarrhea in children and safe from the possible complication of intussusceptions.