乳牛布氏杆菌病的血清琼脂扩散试验

A STUDY ON AGAR GEL DIFFUSION PRECIPITATION TEST IN BOVINE BRUCELLOSIS

琼脂扩散沉淀试验目前已广泛应用于微生物学研究及疾病的诊断,但应用于布氏杆菌病诊断的资料还不多。为了阐明此种试验的实用价值,我们做了一些初步试验。本文报导我们试用于乳牛布氏杆菌病诊断的方法及其结果。

This communication presents data of agar gel diffusion precipitation test for brucellosis of 1076 dairy cows' sera from 3 farms of different infective status.A 2.5% phenol extration of Br.melitensis was used as antigen.The results of the test indicated that a part of sera from cows whose serum contained brucella agglutinin in titers of 1:50—1:100,and most of the sera from cows whose serum contained agglutinin in titers of 1:200 and above were positive to the test; while those from cows vaccinated with the strain 19 within 6 months were all negative in spite of high serum brueella agglutinin titers.All sera from healthy cows tested were negative. In one farm,two formerly separately isolated groups of past reactors were gathered to- gether in one isolation unit,showing indications of flaring up of the infection.This herd was tested in three times with intervals of 2-6 weeks:once before the two groups were brought to-gether and twice after they were intermingled.Results of these tests showed that posi- tive agar gel diffusion precipitation would occur in sera of cows when their serum agglutinin titers were increasing,even when the titers were still in a low level stage. In view of the negative results of all strain 19 vaccinated cows tested and positive re- actions among the sera of cows when the infection became progressive,the authors consider that the agar gel diffusion precipitation test may be used as an aid in differentiation of vaccinated animals from naturally infected ones,and it may also serve as a token of presence of an active brucellar infection in a dairy herd.