Molecular characterisation and ovine live vaccine 1B evaluation toward a Chlamydophila abortus strain isolated from springbok antelope abortion

Chlamydiosis is a zoonosis with a worldwide distribution. The reservoir of susceptible hosts is large and includes birds and both domestic and wild mammals. Chlamydial infection, determined serologically, seems to be widespread among wild ruminants in the Paris zoo (France). In February 2003, an abortion case was reported within the springbok (Antidorcas marsupialis) herd of the zoo. PCR assay using primers targeting the polymorph membrane protein gene (pmp) family was performed on both vaginal swab and placenta samples revealing the presence of Chlamydophila. The inoculation into chicken embryos of an infected placenta extract led to the successful isolation of a C. abortus strain referred to as ASb1. The omp1 gene coding the major outer membrane protein (momp) and the 16S-23S rRNA spacer region of ASb1 were compared to those of various strains by restriction fragment length polymorphism (RFLP). The RFLP analysis showed that this isolate belonged to Chlamydophila abortus species and is highly related to known domestic ruminant's strains causing abortion. The efficacy of a live vaccine 1B, based on a temperature-sensitive mutant of the ovine abortion reference strain AB7, was tested. Protection-challenge experiments in a mouse model show that the ASb1 strain led to mice abortions and that vaccination with 1B vaccine provided them with effective protection.