title: Subclinical Tick-Borne Encephalitis Virus in Experimentally Infected Apodemus agrarius.
abstract: OBJECTIVE
  In this study, we investigated the dose dependence of tick-borne encephalitis virus (TBEV) infection in one of the reservoirs, i.e. Apodemus agrarius, a small rodent species.
  
  
  METHODS
  The animals were challenged with TBEV per os and intramuscularly with infectious doses ranging from 1 to 1,500 plaque-forming units (pfu). Clinical signs were recorded and clinical and pathological features were evaluated by histological, immunohistochemical, and serological methods.
  
  
  RESULTS
  High perorally administered infectious doses resulted in virus replication in the brain, which is the first sign of subclinical viral encephalitis in the Apodemus genus. The animals seroconverted at infectious doses greater than 100 pfu, and all animals remained asymptomatic.
  
  
  CONCLUSIONS
  Our work shows the first evidence that subclinical TBEV encephalitis may occur in Apodemus species, depending on the virus load of the inoculum. The antiviral response of the local innate immune system may influence the resistance of Apodemus individuals to lower infectious doses. Per oral/nasal infection seems to be more dangerous for the host than other routes of infection.
authors.affiliation: Institute for Veterinary Medical Research, Agricultural Research Center of the Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Egyed
authors.forename: Viktor
authors.initials: V
authors.lastname: Zöldi
authors.forename: Levente
authors.initials: L
authors.lastname: Szeredi
mesh_terms: D000818:Animals; D004669:Encephalitis Viruses, Tick-Borne / Q000472:pathogenicity* / Q000502:physiology; D004675:Encephalitis, Tick-Borne / Q000473:pathology / Q000821:virology*; D006801:Humans; D008297:Male; D051189:Murinae; D014779:Virus Replication