1982 Volume 56 Issue 8 Pages 671-678
Experiments were performed in mice to assess the protective effect against S. enteritidis infection of SPA purified from S. enteritidis strain 2547. Single injection of purified SPA, 0.05μg i.p., provided protection in 80% of mice against death from infection by challenge with 104 LD50 of the organism 14 days after injection (previous report).
When normal mice were challenged with 100 LD50 of the organism after passive transfer of mouse anti-serum to purified SPA, 90% of the mice survived, whereas all normal controls receiving passive transfer of normal mouse serum died following the challenge. Bacterial enumeration in these animals showed growth of the pathogen to 105 organism/ml in the blood and 108/g in the spleen and liver of the controls at 3 days after infection. The pathogen did not multiply to reach such high blood and visceral levels and gradually diminished in number to become completely eliminated in 30 days after challenge in the immune serum injected group.
There was little or no bactericidal effect of the immune serum, but a significant increase of bactericidal rate was evident as compared to controls when the immune serum was combined with normal macrophages and incubated with the challenging pathogen, followed by enumeration of viable bacteria.
Normal mice given the immune serum by passive transfer after intraperitoneal injection of carrageenan for suppression of macrophage function, all died following a subsequent change with the pathogen.
The data obtained have demonstrated the IgM was the component taking a principal part in this protection against S. enteritidis infection, among other antibodies contained in the immune serum.
