Multiplication of the IBR, PI-3 and BVD-MD viruses in cell and organ cultures of bovine fetuses after experimental intrauterine infections

The intrauterine infection of four- to nine-month-old bovine foetuses with the PI-3, BVD-MD viruses, performed 7 to 72 days prior to their delivery, did not exert any significant influence upon the susceptibility of primary cell cultures from foetal organs and tissues to further viral infection in vitro. The BVD-MD and IBR viruses multiplied in the primary cell cultures from the organs of a foetus infected with the PI-3 virus seven days before delivery even in the presence of endogenous PI-3 virus. Persisting infection with the PI-3 virus also failed to influence the susceptibility of foetal organ cultures to infection with the IBR and PI-3 viruses in vitro. The IBR virus and endogenous PI-3 virus multiplied simultaneously to high titres in the organ cultures of thymus and lungs whereas in the organ cultures of kidneys, spleen and testes the multiplication of endogenous PI-3 virus was suppressed.