Passive immunity to contagious bovine pleuropneumonia.

A significant passive protection against contagious bovine pleuropneumonia (CBPP) was demonstrated in cattle. One group of cattle was inoculated with serum from CBPP-recovered cattle, while another group was inoculated with serum from susceptible cattle. The two groups, along with an untreated control group, were challenged with the virulent Gladysdale strain of Mycoplasma mycoides, using the in-contact method. Four out of the five cattle inoculated with serum from animals which had recovered from CBPP were protected, whereas three of five cattle inoculated with serum from susceptible animals and all the untreated animals died of CBPP.