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Published on: December 8, 2011
Immunity to mycoplasmal infection of the genital tract: a mouse model
Abstract:
Thirty-three TO mice, 24 of which had received progesterone, were infected originally by Mycoplasma pulmonis given vaginally. Thirty-one of the mice were free of the organisms in the genital tract 236 days later at which time all of them were treated again with progesterone and rechallenged with M. pulmonis vaginally. All 31 mice were resistant. In contrast, of 21 TO mice of the same age that were not infected originally 15 (71%) became infected persistently after vaginal rechallenge. In similar experiments, 12 CBA mice, nine of which had received progesterone, were infected originally. Ten of these mice were free of the organisms genitally 2 years later, at which time all of them were rechallenged vaginally. Only two mice (20%) were reinfected, whereas six (86%) out of seven mice, not infected originally, were reinfected. Autopsy examination revealed that neither infection nor immunity was confined to the lower genital tract. Thus, M. pulmonis organisms were not detected in the upper tract of five TO mice that remained mycoplasma-free vaginally after rechallenge. The contribution of oropharyngeal M. pulmonis infection, which occurred in most of the mice, to the solid, long-lasting genital-tract resistance was difficult to assess, but in two mice, at least, immunity was not afforded by such infection.
Insights
Mice previously infected with Mycoplasma pulmonis developed strong genital tract resistance. This immunity persisted even after progesterone treatment and rechallenge, indicating a long-lasting immune response.
Area of Science:
- Immunology
- Microbiology
- Veterinary Science
Background:
- Mycoplasma pulmonis is a common pathogen affecting the respiratory and genital tracts of rodents.
- Understanding host immune responses is crucial for developing effective control strategies against Mycoplasma infections.
Purpose of the Study:
- To investigate the development of long-lasting resistance in mice following vaginal infection with Mycoplasma pulmonis.
- To assess the impact of progesterone treatment on Mycoplasma pulmonis infection and subsequent immunity.
Main Methods:
- Mice (TO and CBA strains) were initially infected vaginally with Mycoplasma pulmonis.
- Mice were treated with progesterone and rechallenged with M. pulmonis at different time points (236 days and 2 years).
- Infection status and immune resistance were evaluated through vaginal swabs and autopsy examinations.
Main Results:
- Mice with prior M. pulmonis infection demonstrated significant resistance to rechallenge, with nearly all remaining infection-free.
- Naïve mice, when rechallenged, showed high rates of persistent infection (71% in TO mice, 86% in CBA mice).
- Progesterone treatment did not abrogate the established resistance in previously infected mice.
Conclusions:
- Prior vaginal infection with Mycoplasma pulmonis confers solid, long-lasting resistance against subsequent genital tract reinfection in mice.
- The immune memory established by M. pulmonis infection is robust and not easily overcome by progesterone treatment or rechallenge.
- Further research is needed to elucidate the mechanisms underlying this durable immunity and the role of oropharyngeal infection.
