BACKGROUND: Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. When host population densities fluctuate, low levels of virulence with limited impact on the host are expected, as this should increase the likelihood of surviving periods of low host density. We examined the effects of Morogoro arenavirus on the survival and recapture probability of multimammate mice (Mastomys natalensis) using a seven-year capture-mark-recapture time series. Mastomys natalensis is the natural host of Morogoro virus and is known for its strong seasonal density fluctuations. RESULTS: Antibody presence was negatively correlated with survival probability (effect size: 5-8% per month depending on season) but positively with recapture probability (effect size: 8%). CONCLUSIONS: The small negative correlation between host survival probability and antibody presence suggests that either the virus has a negative effect on host condition, or that hosts with lower survival probability are more likely to obtain Morogoro virus infection, for example due to particular behavioural or immunological traits. The latter hypothesis is supported by the positive correlation between antibody status and recapture probability which suggests that risky behaviour might increase the probability of becoming infected.

• MeSH
• analýza přežití MeSH
• Arenavirus imunologie   izolace a purifikace   MeSH
• chování zvířat MeSH
• infekce viry z čeledi Arenaviridae mortalita   veterinární   MeSH
• Murinae * MeSH
• nemoci hlodavců mortalita   virologie   MeSH
• protilátky virové krev   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We determined the role of Yersinia pestis virulence markers in an animal model of pneumonic plague. Eleven strains of Y. pestis were characterized using PCR assays to detect the presence of known virulence genes both encoded by the three plasmids as well as chromosomal markers. The virulence of all Y. pestis strains was compared in a mouse model for pneumonic plague. The presence of all known virulence genes correlated completely with virulence in the Balb/c mouse model. Strains which lacked HmsF initially exhibited visible signs of disease whereas all other strains (except wild-type strains) did not exhibit any disease signs. Forty-eight hours post-infection, mice which had received HmsF(-) strains regained body mass and were able to control infection; those infected with strains possessing a full complement of virulence genes suffered from fatal disease. The bacterial loads observed in the lung and other tissues reflected the observed clinical signs as did the cytokine changes measured in these animals. We can conclude that all known virulence genes are required for the establishment of pneumonic plague in mammalian animal models, the role of HmsF being of particular importance in disease progression.

• MeSH
• analýza přežití MeSH
• bakteriální geny MeSH
• bakteriální nálož MeSH
• cytokiny sekrece   MeSH
• DNA bakterií genetika   MeSH
• faktory virulence genetika   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• mor mikrobiologie   mortalita   patologie   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• nemoci hlodavců mikrobiologie   mortalita   patologie   MeSH
• plazmidy analýza   MeSH
• plíce mikrobiologie   MeSH
• polymerázová řetězová reakce MeSH
• proteiny vnější bakteriální membrány genetika   metabolismus   MeSH
• tělesná hmotnost MeSH
• virulence MeSH
• Yersinia pestis genetika   patogenita   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH