Detection of human IgG antibodies against Mycoplasma genitalium using a recombinant MG075 antigen

Mycoplasma genitalium is a sexually transmitted pathogen, which can cause a range of reproductive tract diseases in both men and women. To disentangle the relationship between M. genitalium infection(s) and subsequent reproductive health complications at the population level, accurate serological tools are needed. The major challenge in developing specific M. genitalium serological tests is the extensive cross-reactivity with the closely related ubiquitous respiratory tract pathogen, M. pneumoniae. In this report, we describe the development of an immunoblot assay based on a recombinant fragment of the M. genitalium MG075 protein present in lipid-associated membrane extracts. A sensitivity of 87.1% was achieved based on testing antibody responses in sera from 101 adults with PCR-confirmed M. genitalium infection. A specificity of 95.2% was obtained through evaluation of sera from 166 children under 15 years of age with and without M. pneumoniae infection, who were unlikely to have been exposed to sexually transmitted M. genitalium. The development of a serological assay capable of accurately distinguishing M. genitalium and M. pneumoniae, will enable a better understanding of associations between M. genitalium and adverse reproductive sequelae.