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Horizontal transmission of murine retroviruses
Abstract:
Both a feral mouse ecotropic virus (WM-E) and Friend ecotropic virus (F-MuLV) were transmitted horizontally among adult mice. Infection resulted in the production of antiviral antibody in the recipients, with no evidence of viremia or clinical disease. However, persistent low-level virus replication was detectable in the spleens of these mice as long as 8 months after initial infection. External secretions, including saliva, semen, and uterine secretions from viremic mice contained high concentrations of infectious virus. Nevertheless, transmission occurred only from viremic males to either males or females. Male-to-male transmission appeared to occur by parenteral inoculation of infectious saliva during fighting behavior. Evidence is presented that infection of females was by the venereal route. Of four mouse strains examined, NFS/N, IRW, and C57L females were all susceptible to venereal infection, whereas AKR mice were not. Since AKR mice are susceptible to infection by WM-E administered parenterally, this resistance appeared to be mediated by local viral interference due to the high-level expression of endogenous Akv gp70 within the female reproductive tract. Although both WM-E and F-MuLV were transmitted from viremic males to females, infection by WM-E was significantly more efficient than that by F-MuLV. This difference correlated with a distinct difference in cellular tropism of WM-E and F-MuLV within the epididymis of viremic males. F-MuLV gp70 was expressed only within stromal elements, whereas WM-E gp70 was seen largely within the epithelial lining cells and luminal contents of the duct. No evidence of virus expression within germ cells was observed. The possible influence of virus expression by epithelial cells of the female reproductive tract on infection of embryos is discussed.
Insights
Horizontal transmission of mouse ecotropic viruses occurred between adult mice, with persistent low-level replication detected. Viremic males transmitted viruses via saliva and semen, with females susceptible through venereal routes, except for AKR mice due to viral interference.
Area of Science:
- Virology
- Mouse Models
- Retroviruses
Background:
- Horizontal transmission of retroviruses like feral mouse ecotropic virus (WM-E) and Friend ecotropic virus (F-MuLV) among adult mice is a significant concern.
- Understanding transmission routes and host resistance mechanisms is crucial for controlling viral spread and disease.
- Previous studies have highlighted the role of external secretions in viral shedding but detailed routes of transmission require further investigation.
Purpose of the Study:
- To investigate the horizontal transmission dynamics of WM-E and F-MuLV between adult mice.
- To identify the routes of viral transmission and factors influencing susceptibility.
- To explore the role of endogenous viral elements in conferring resistance to infection.
Main Methods:
- Adult mice were inoculated with WM-E or F-MuLV to establish viremia.
- Transmission studies were conducted between infected and susceptible mice via direct contact, saliva, semen, and uterine secretions.
- Viral replication was monitored in spleens, and viral presence in secretions was quantified.
- Susceptibility of different mouse strains (NFS/N, IRW, C57L, AKR) to venereal and parenteral infection was assessed.
- Immunohistochemistry was used to examine viral tropism in the male reproductive tract.
Main Results:
- Horizontal transmission occurred from viremic males to females (venereal route) and males (parenteral, via saliva during fighting).
- Infection led to antibody production but no viremia or clinical disease, with persistent low-level splenic replication.
- AKR females showed resistance to venereal infection, attributed to local viral interference from endogenous Akv gp70 expression.
- WM-E transmission to females was more efficient than F-MuLV, correlating with WM-E's tropism for epididymal epithelial cells and luminal contents, unlike F-MuLV's stromal tropism.
Conclusions:
- Male mice can efficiently transmit WM-E and F-MuLV horizontally through saliva and semen, primarily via venereal routes in females.
- Host resistance, exemplified by AKR mice, can be mediated by endogenous viral elements interfering with superinfection.
- Differential tropism of viruses within the male reproductive tract influences transmission efficiency, with implications for understanding retroviral spread and host-pathogen interactions.