Phagocytosis and intracellular killing of Pasteurella multocida by porcine alveolar macrophages after infection with pseudorabies virus.

The purpose of this study was to determine if pseudorabies virus (PrV) interfered with normal alveolar macrophage phagocytic functions. Porcine alveolar macrophages (PAM) obtained by pulmonary lavage were exposed to PrV. At 1 hour postinfection, cells were challenged with Pasteurella multocida labeled with 3[H] thymidine. The phagocytosis assay was performed by measuring total radioactivity 1 hour after Pm challenge in a soft-beta spectrophotometer. Intracellular killing was measured by counting viable bacteria 3 hours after P. multocida challenge. Phagocytic values of PrV-infected and control PAM ranged from 11% to 20%, a non-significant difference. Values for intracellular killing for PrV-infected PAM ranged from 7.1 X 10(5) to 1 X 10(6) in contrast to 5.1 X 10(1) to 1.8 X 10(2) for the control PAM. This difference in killing function was significantly lower in PrV-infected PAM than in control cells (P less than 0.01). This alteration of macrophage function may be a factor in the pathogenesis of PrV-Pm mediated pneumonia in pigs.

Single-dilution indirect solid-phase radioimmunoassay for the detection of anti-pseudorabies immunoglobulin G in swine sera.

A single-dilution indirect solid-phase radioimmunoassay (IRIA) was developed for the detection of low levels of anti-pseudorabies immunoglobulin G in swine sera. The assay derived increased sensitivity from the use of a second amplifying antibody. The IRIA was examined for its stoichiometry, amplification by secondary antibody, advantage of a single-dilution assay vs an end-point titration, sensitivity, and specificity. The assay had a near linear dose-response relationship with positive sera (serum-neutralization titer less than or equal to 1:16) and lacked a dose response with negative sera. With addition of the secondary antibody, the IRIA was enhanced 8.5-fold in net specific binding, and the end-point titer was amplified 32-fold. The single-dilution assay was proved to be a feasible test, compared with end-point titration. Anti-pseudorabies virus titers were at least 128-fold higher by IRIA than those by serum-neutralization test. Evidence indicated that there may be minimal or no cross-reactivity of IRIA antigen with anti-infectious bovine rhinotracheitis sera. The single-dilution IRIA was a rapid and sensitive test for anti-pseudorabies virus immunoglobulin G in swine sera.

Serological survey for Aujeszky's disease in native sows of Canada.

A serological survey was initiated to uncover subclinical foci of infection with pseudorabies virus. A total of 2819 serum samples, collected from sows during February to November 1977, were found negative for antibodies to pseudorabies virus.