DEVELOPMENT OF AN INTRAPERITONEAL IMPLANT CHAMBER FOR THE STUDY OF INVIVO-GROWN PASTEURELLA-HAEMOLYTICA IN CATTLE

An intraperitoneal implant chamber was developed for the study of the in vivo growth of Pasteurella haemolytica in calves. The chamber had a volume of approximately 100 mi and featured an external sampling port which allowed multiple and sequential sampling of the chamber content s. A single polycarbonate diffusion membrane with a pore size of 0.22 mu m allowed host peritoneal fluid to diffuse into the chamber and mai ntained the bacterial population free of white blood cells. Chambers w ere implanted into the peritoneal cavities of four five-month-old dair y-cross carves, demonstrated to be sere-negative by indirect haemagglu tination assay. Three days later, four different P. haemolytica isolat es, of serotypes Al or A2, were inoculated into the chambers. In all c ases, there was a slow decline in the viable bacterial numbers within the chambers. Western blot analysis of the antibody content of the cha mber fluids revealed IgG antibodies to P. haemolytica OMPs in the flui d prior to inoculation and both 9 and 15 days after inoculation. Furth ermore, there was no significant change in the IgG antibody content of the chamber fluid, either quantitatively or qualitatively, during the course of the experiment. Analysis of the bactericidal activity of pr e-inoculation chamber fluid against the corresponding bacterial isolat e suggested that an antibody-dependent complement-mediated process was not responsible for the decline in bacterial numbers. Overall, the ch amber design was demonstrated to be extremely effective for in vivo st udies of P. haemolytica in calves, allowing easy and regular sampling of the chamber contents and maintaining bacteria free of white blood c ells. Although there was a slow decline in bacterial numbers over time , sufficient numbers of cells could be obtained for analysis of cell-s urface antigens.