Isolation of antigenic variants of leptospiras from puppies and pigs experimentally infected with Leptospira interrogans serovars canicola and pomona.

Abstract

For the purpose of isolating antigenic variants of leptospiras from domestic animals, Leptospira interrogans serovars canicola and pomona were inoculated into puppies and spesific-pathogen-free (SPF) pigs respectively, and the blood and kidneys of those animals were inoculated onto the solid medium each containing homologous immune serum. Colonies developed on the medium were divided into large, medium and small colonies. Some of these colonies picked at random were antigenically compared with the parent by a screening test using the precipitin-absorption test in gel. In the case of canicola, the antigenic variants were isolated from the blood of 7 of the 10 infected puppies. The antigenic variants were found in a large number of the large colonies from the blood and kidneys, and in a small number of the medium and small colonies from the blood, and none of the medium and small colonies from the kidneys. The antigenic variants were also isolated from the inocula, but they were isolated more frequently from the blood of the puppies than from the inocula. In the case of pomona, the antigenic variants were isolated only from the small colonies from the blood of 2 of the 5 infected pigs. Large colonies were never developed from the specimens of the pigs. The antigenic variants were isolated more frequently from the blood of the pigs than from the inocula. The variants were confirmed to be antigenically diffetent from their parent. The variants originated from the same parent were antigenically similar to one another. These results indicate that canicola Moulton and pomona MLS contained a small percentage of the antigenic variants and that the percentage of the variants was raised significantly, 3 to 7 days after the infection, in the blood of the puppies and pigs.