Studies of the complement fixation reaction in virus systems. VI. In vesicular stomatitis in horses, cattle, and swine.

This research article explores how sera from different animals (horses, cattle, and swine) behave when exposed to types of the vesicular stomatitis virus. Detailed examinations include analyzing activities of these sera during complement fixation tests, observing any similarity or differences in antibody development timing, and investigating factors contributing to observed phenomena.

Introduction and Methodology

• The research focuses on exploring the behavior of animal sera (from horses, swine, and cattle) when exposed to either the New Jersey or Indiana types of vesicular stomatitis virus.
• These sera were collected before the animals’ inoculation with the virus and at periodic intervals thereafter.
• Complement-fixation methods were used to test blood serum using antigens derived from chick embryo tissues infected with the respective viruses.

Findings in Horses

• In horses, a complement-fixing activity with VS antigen emerged around 6-8 days after the infection, peaking in 10-14 days.
• This activity remained relatively constant for 7-10 days and then began to decline.
• There was no recorded cross-fixation between the types of vesicular stomatitis virus.

Findings in Cattle

• The sera from cattle did not exhibit any fixation in direct complement-fixation tests with homologous antigen at any time.
• To detect the presence of non-complement-fixing antibodies in the bovine sera, it became necessary to use an indirect complement-fixation method. This involved using hyperimmune guinea pig or convalescent horse serum to recognize residual antigen.
• The timing of antibody development, as indicated by the emergence of inhibitory activity in these indirect tests, corresponded with what was observed in horses using direct complement-fixation tests.

Findings in Swine

• Serum from convalescent pigs showed significant prozone effects, displayed as increased hemolysis at lower serum dilutions.
• This increase in hemolysis could be attributed to certain substances present in regular as well as convalescent swine serum. It is not due to non-complement-fixing antibodies similar to those in convalescent bovine serum.
• Elements like natural hemolysins for sheep red cells, the third component of complement, and possibly other constituents like lipids, seemingly contribute to this increased hemolysis or reduced fixation of complement.