Experimental Infection with Mycobacterium Avium, Serotype 2, in Pigs

Abstract

The immunizing effect of BCG vaccination against infection with M. avium was evaluated in pigs on the basis of clinical and pathological findings and numbers of acid-fast organisms in the tissues.

In experiments with small and large challenge doses i.v. (10⁻² and 5 mg) the vaccinated animals were found to be partially protected. As compared to non-vaccinates, a reduction of viable organisms was found in vaccinates examined 28-31 or 70-73 days after challenge (Table 4), and fewer positive tissues were found in vaccinates than in non-vaccinates (Table 3). The most obvious results were seen in the experiment with a challenge dose of 10⁻² mg i.V., where the number of organisms was consistently smaller in vaccinates than in non-vaccinates (Table 4). In contact infection experiments, the observations in both vaccinated and non-vaccinated pigs were limited and the results difficult to evaluate. There seemed to be a protection, as judged by histopathological and cultural findings. kw|Keywords|k]Mycobacterium avium, Serotype 2; k]BCG vaccination; k]challenge, intravenous, oral; k]pigs

Sammendrag

I forsøg med lille og stor challenge dosis, i.v. (10⁻² og 5 mg) fandtes en beskyttende effekt af vaccinen. Ved dyrkningsunders0gelser fandtes terre bakterier hos vaecinerede dyr undersøgt 28–31 eller 70–73 dage efter challenge (tabel 4), og patologisk-anatomiske under-søgelser viste faerre positive organer hos de vaccinerede dyr (tabel 3). De mest overbevisende resultater fandtes i forsøget, hvor 10⁻² mg anvendtes som challenge, idet der her sås systematisk faerre bakterier hos de vaccinerede dyr (tabel 4). I forsøg med kontaktsmitte var fundene meget begrsensede både hos vaccinerede og ikke-vaccinerede dyr, og en sikker konklusion kan ikke udledes af forsøgene. Der synes dog at vaere en beskyttende effekt af BCG vaccinen bed0mt på resultater af dyrkning og patologisk-anatomiske undersøgelser.