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Infection of wild and laboratory animals with Machupo and Latino viruses
Abstract:
Natural infection with Machupo and Latino viruses occurs only in the cricetine rodent Calomys callosus. Machupo virus induces fatal infection in suckling mice and hamsters, and in adult guinea-pigs, marmosets, and rhesus monkeys. Latino virus kills only suckling hamsters; it produces chronic but non-viraemic infection in Calomys rodents.Machupo virus, in contrast, induces a viraemic immunotolerant infection in suckling Calomys, and a split response in animals more than 9 days of age. Tolerant infection is associated with haemolytic anaemia and splenomegaly, lesions not observed in animals able to clear viraemia and produce circulating neutralizing antibodies. Experimental increase in the fraction of tolerant response was obtained by decreasing the virus dose or by phenotypic inbreeding of rodents. Long-term effects of tolerant infection included mild runting, decreased survival time, and almost total sterility among females, largely caused by fatal virus infection of embryos.
Insights
Machupo virus causes fatal infections in various animals, but Calomys callosus rodents develop a unique tolerant infection. This tolerant response leads to severe health issues and reproductive failure in these rodents.
Area of Science:
- Virology
- Immunology
- Rodent models
Background:
- Machupo and Latino viruses infect the rodent Calomys callosus.
- Machupo virus is fatal in multiple animal models, while Latino virus primarily affects suckling hamsters.
- Calomys callosus rodents exhibit distinct responses to Machupo virus infection.
Purpose of the Study:
- To investigate the immune response of Calomys callosus to Machupo virus.
- To understand the mechanisms behind Machupo virus-induced immunotolerance in rodents.
- To identify the long-term consequences of Machupo virus infection in Calomys callosus.
Main Methods:
- Experimental infection of Calomys callosus with Machupo virus.
- Analysis of immune responses, including viraemia and antibody production.
- Assessment of clinical signs, pathological lesions, and reproductive outcomes.
Main Results:
- Machupo virus induces a viraemic, immunotolerant infection in suckling Calomys callosus.
- Older Calomys callosus exhibit a split immune response.
- Tolerant infections are linked to hemolytic anemia, splenomegaly, reduced survival, and female sterility due to embryonic viral infections.
- Decreasing virus dose or inbreeding rodents increased the tolerant response.
Conclusions:
- Calomys callosus serves as a natural reservoir for Machupo virus, developing a unique immunotolerant infection.
- Machupo virus infection in this rodent model has severe long-term health and reproductive consequences.
- Understanding this host-pathogen interaction is crucial for managing arenaviral diseases.