Theiloviruses (TMEV, RTV)

RNA virus, nonenveloped.
 
Prevalence
Common in laboratory colonies, and wild rats and mice.
 
Diagnosis
Serology or PCR.
 
Disease
Disease in mice can result from the rare occurrence of viraemia, which occurs most frequently around 6 – 10 weeks of age. In most cases, natural infection with theiloviruses is asymptomatic.
 
Strains
Several strains have been identified.
 
Screening
Regular serological testing is recommended.
 
Transmission
TMEV and RTV are shed through the faecal – oral route.
 
Duration
In the case of TMEV, animals are persistently infected and virus is shed for approximately two months after infection.
 
Durability
Environment should be chemically decontaminated with the help of detergents and oxidising agents. Materials in contact with animals should be autoclaved or cold sterilised.
 
Significance
Rare as a natural infection of contemporary mice and rats. TMEV can interfere with research on the nervous system, immune system and musculoskeletal system. Little is currently known about the effects of RTV on research in rats and consequently an infection should be treated with caution.
 
Control
Culling and replacing infected animals. Hysterectomy rederivation and embryo transfer.
 
Reading
  • Infectious Diseases of Mice and Rats. National Research Council 1991.
  • Charles River Laboratories website, www.criver.com