Measurement of the efficacy of vaccines and antimicrobial therapy against infection with Toxoplasma gondii

To facilitate studies of vaccines and antimicrobial agents effective agains t Toxoplasma gondii infection, an assay system was developed to semi-quanti tate parasitaemia using PCR amplification of T. gondii DNA obtained from th e blood of mice infected with the parasite. A competitive internal standard DNA fragment of the B1 gene of T. gondii was generated and used in PCR so that the amplified product could be semi-quantitated and false negative res ults could be avoided. The PCR assay system was used to analyse the levels of parasitaemia in immunised and antimicrobial agent treated mice at variou s times after infection with T, gondii. The results of these studies indica te that this highly sensitive detection method is a rapid and reliable proc edure that can be employed to assess the abilities of vaccines or antimicro bial agents to provide protection early following T. gondii infection. (C) 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.