Simultaneous vaccination of cattle with foot-and-mouth disease and vesicular stomatitis live virus vaccines.

Four- to six- month-old cattle were simultaneously vaccinated with foot-and-mouth disease (FMD) and vesicular stomatitis (VS) live virus vaccines by injection of FMD vaccine in one side of the body and VS vaccine in the other side. These cattle were again vaccinated with FMD and VS vaccines given simultaneously three and nine months after the first vaccination. The antibody levels of the vaccinated animals were studied by serum protection test in suckling mice and results were compared with those obtained when cattle are vaccinated either with FMD alone or with VS vaccine alone. It appears that an interference mechanism is responsible for the lack or the low levels of antibody formation observed in the animals simultaneoulsy vaccinated with the two vaccines.