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A bile agar migration (BAM) test was used to determine the viability of Dictyocaulus viviparus larvae in lungworm vaccines. Percentage migration values for 10 batches of vaccine varied from 8.8 to 33.2 per cent compared with 99 per cent of unirradiated larvae tested under similar conditions. On the other hand a conventional viability count (CVC), based on subjective assessment of larval shape, gave figures of 95.1 to 98.7 per cent for the 10 vaccine batches. The BAM test may therefore have potential for providing a more discriminatory assessment of vaccine quality than CVC.

SummaryThe nature of the antibodies detectable by the microscopic agglutination test for bovine leptospirosis was examined. Density gradient ultracentrifugation, gel filtration and disulphide-bond-reduction experiments indicated that antileptospiral agglutinating activity was present in both IgM and IgG immunoglobulin fractions. This was confirmed by selective precipitation of specific antibody classes and ion-exchange chromatography.

A total of 2994 sera, from approximately equal numbers of aborting and normal calving cows, were examined for leptospiral antibodies using a complement fixation test. An analysis of the results indicated that approximately 10% of abortions were associated with leptospiral antibodies.

The sporicidal effect of peracetic acid on Bacillus anthracis spores was investigated. A complete sporicidal effect was observed at a concentration of 3 per cent. This concentration is recommended for the treatment of infected pastures and soil.

Subcutaneous injection of 235 micrograms endotoxin from E coli 08: K87, K88ab into two sows 14 days before the expected farrowing date elicited a toxic shock reaction but the sows recovered and farrowed normally. No reaction was observed in two other sows which had received endotoxin-free 0.9 per cent saline. In a subsequent pregnancy, the same four sows were injected subcutaneously with 23 mg of the same endotoxin preparation. Those which had previously received endotoxin exhibited a severe shock reaction and aborted after 28 and 40 hours, respectively, while the other two sows showed a milder reaction and farrowed normally.

A total of fifty production batch samples from six different vaccines for pigs, sheep and cattle were monitored for their endotoxin content. All vaccines recommended for parenteral administration into pregnant animals were aqueous and cellular with the exception of one comprising enterotoxin only. The Limulus amoebocyte lysate test was used for endotoxin determination. Total endotoxin of the vaccine was estimated and a method has been devised to estimate the enterotoxin bound either to the cells or the adjuvant. The highest endotoxin levels obtained for pigs, sheep and cattle vaccines were 47.9 micrograms ml-1, 4.7 micrograms ml-1 and 2.4 micrograms ml-1 respectively. All these vaccines have been found to be safe in pregnant animals. The non-cellular vaccine containing enterotoxin only had an endotoxin level of 0.47 microgram ml-1.

Fifteen batches of E. coli vaccines for pigs, from three different manufacturers, were subjected to a quantitative form of the in vitro Limulus-amoebocyte-lysate (LAL) test for their free endotoxin content. A batch of vaccine associated with abortions in pregnant sows was found to contain a much higher level of free endotoxin than batches of vaccine not associated with abortion. The evidence of these assays suggests that they will be useful in the quality control of E. coli vaccines.

WE report here the presence of virulent anthrax bacilli in aborted tissues. This is significant in that it suggests that the foetus becomes infected during the bacteraemia/pyrexia phase of the dam, and that the bacilli continue to multiply in and cause the death of the foetus despite the recovery with treatment in the parent cow. Since abortion may be a sequel to the infection in pregnant animals which survive, the products of such abortions must be regarded as potential vectors of anthrax both for man and other animals.