pestis within its host depends on evasion of the host’s innate immune system, and on circumventing phagocytosis and antimicrobial effectors. Genetic background, like CCR5 gene and Class I Major Histocompatibility Complex polymorphisms, seems important for this resistance l. rattus and Rattus norvegicus, a higher resistance to the disease is observed in rats from endemic areas compared to those from plague-free zones. The black rat, Rattus rattus, is its main reservoir in rural areas. Madagascar is the country worst affected by plague in the world with an average of 500 human cases annually especially in the central highlands. Few studies have demonstrated differences in plague resistance in wild rodents originated or not from separate field populations as reported in Western United States, in South Africa and in Madagascar. Host resistance to plague is influenced by many factors including rodent species, genetic factors, and prior immunity. Plague, a flea-borne zoonosis, is caused by Yersinia pestis and is mainly associated with rodents. In Madagascar, these results support the role of black rat as long term reservoir of infected fleas supporting maintenance of plague transmission. In addition, F1 rats from endemic areas exhibited higher survival rates than those from non-endemic ones, suggesting a selection of a resistant lineage. During challenge, cytokine profiles support activation of specific immune response associated with the bacteria control. pestis greatly increase survival of rats to subsequent challenge with a lethal dose. Survival rate and antibody immune responses were analyzed. For this purpose, laboratory-born rats were obtained from wild black rats originating either from plague-endemic or plague-free zones, and were challenged with Y. We investigate the hypothesis that lineages of rats can acquire resistance to plague and that previous contacts with the bacteria will affect their survival, allowing maintenance of infected fleas. However we previously reported that black rats from endemic areas can survive the infection whereas those from non-endemic areas remained susceptible. The rat is assumed to die shortly after infection inducing migration of the fleas. In Madagascar, plague ( Yersinia pestis infection) is endemic in the central highlands, maintained by the couple Rattus rattus/flea.
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