Neuropathology induced by infection with Friend murine leukemia viral clone A8-V depends upon the level of viral antigen expression.
A8-V is a neuropathogenic clone isolated from the Friend murine leukemia virus which causes spongiosis in the rat brain after infection at birth. Serial studies using chimeric viruses derived from the A8-V and the 57 virus (57-V), which is a non-neuropathogenic strain of Friend murine leukemia virus, proved that the long terminal repeat (LTR) and 5' leader (LTR-leader/A8) derived from A8-V, in addition to the env gene (env/A8) of A8-V, are necessary for the neuropathogenesis of A8-V. The enhancer element within the LTR of A8-V (LTR/A8) has been supposed to contribute to the severe manifestation of spongiosis by inducing high levels of viral production in the brain after A8-V infection. However, the recombinant viruses R7c and R7f, which lack the enhancer element of A8-V, induced spongiosis with high incidence rates, although the isolated viral titers of the infected brain display very low levels, which are even comparable to the 57-V infection. Immunohistochemical studies demonstrated that infection with neuropathogenic chimerae, R7c and R7f, induced increased expression of viral antigens than that produced by infection with non-neuropathogenic chimeric virus, Rec5, despite the fact that R7c, R7f and Rec5 all exhibited similar levels of viral proliferation in the brain postinfection. Thus, neuropathology induced by A8 infection is not dependent upon the viral proliferation rate but rather the level of viral antigen expression.
Watanabe
Rihito
R
Department of Bioinformatics, Faculty of Engineering, Soka University, Tangi-cho 1-236, Hachioji, Tokyo 192-8577, Japan. rihito@t.soka.ac.jp
Takase-Yoden
Sayaka
S
D000818:Animals; D000956:Antigens, Viral / Q000096:biosynthesis*; D001927:Brain Diseases / Q000276:immunology / Q000473:pathology* / Q000821:virology*; D002999:Clone Cells; D004742:Enhancer Elements, Genetic; D005622:Friend murine leukemia virus / Q000235:genetics; D007150:Immunohistochemistry; D009457:Neuroglia / Q000821:virology; D051381:Rats; D011917:Rats, Inbred Lew; D012192:Retroviridae Infections / Q000378:metabolism / Q000473:pathology*; D014412:Tumor Virus Infections / Q000378:metabolism / Q000473:pathology*
D000956:Antigens, Viral