A recommended method for the preparation of monospecific Brucella sera.

A method is described in detail for the preparation of monospecific sera for typing brucella cultures. The importance of using entirely smooth cultures throughout the procedure is emphasized. A single intravenous injection of living brucellae in rabbits caused an active infection and the early appearance of high-titre antibodies. Sera obtained five to seven days after inoculation contained a higher proportion of specific antibodies than serum obtained ten days after inoculation. Trial absorptions of each serum sample were performed to determine the relative content of homologous and heterologous antibodies, so that the optimum proportions of absorbing cells to serum could be employed for the final absorption. In this manner sera were obtained which at a 1/160 dilution agglutinated the homologous antigen and at a 1/10 dilution did not agglutinate the heterologous antigen.Monospecific sera were used in typing 180 brucella strains isolated in Great Britain and other countries, and over 3000 cultures recovered from experimental infections. With the exception of two strains of Br. melitensis, all cultures were agglutinated to titre with only one of the monospecific sera.