Serological relationships between rotaviruses from different species as studied by complement fixation and neutralization.

Human, piglet, mouse, foal, lamb, calf and rabbit rotaviruses all infected, but could not readily be subcultured in LLC MK2 cells. Cells infected with mouse and calf rotaviruses reacted by indirect immunofluorescence (FA) with convalescent serum from children, piglets, mice, foals, lambs, calves or rabbits, taken after rotavirus infection. Human, calf, piglet, mouse and foal rotaviruses reacted with human, calf, mouse, foal and lamb convalescent serum by complement fixation (CF). It was not possible to distinguish between different rotaviruses by CF or FA. Neutralization tests, however, detected species-specific rotavirus antigens. Any virus was neutralized by a much higher dilution of homologous species convalescent serum than by any heterologous serum. With the exception of the mouse virus there was very little cross reaction. However, in sera with a very high neutralizing titre for the homologous virus the titre was proportionately raised against heterologous virus. It is, therefore, now possible to type to species an unknown rotavirus by a neutralization test in LLC MK2 cells using convalescent serum from each species.