No abstract

Theiler murine encephalomyelitis viruses (TMEVs) are picornaviruses that cause enteric and neurological disease in mice. The GDVII strain and other members of the GDVII subgroup are highly virulent and cause an acute, fatal polioencephalomyelitis following intracerebral inoculation, whereas the DA stain and other members of the TO subgroup cause a persistent, demyelinating infection. We previously produced a full-length, infectious DA cDNA clone. We now describe the generation of a full-length, infectious GDVII cDNA clone and the subsequent production of intratypic chimeric cDNAs and intratypic recombinant viruses. Inoculation ofthe recombinant viruses into mice demonstrated that a major determinant of TMEV neurovirulence is within the GDVII 1B (capsid protein VP2)-2C coding region, most likely in the GDVII 1B (VP2)-2A coding region. Genomic sequences 5' to this region of GDVU RNA also contribute to expression of the full neurovirulence phenotype. These data demonstrate the multigenic nature of TMEV neurovirulence, as has been reported for other viruses.Neurovirulence, the ability of a virus to kill following central nervous system infection, has been a topic of considerable interest for virologists. Infections with picornaviruses, such as poliovirus, have provided useful systems for the study of neurovirulence. For over three decades investigators have sought a molecular basis for the attenuation of neurovirulence seen in poliovirus vaccine strains. The recent development of recombinant viruses generated from infectious chimeric parental and vaccine poliovirus cDNA clones, as well as the use of site-directed mutagenesis of infectious clones, have provided the means to delineate the molecular determinants of poliovirus neurovirulence (reviewed in refs. 1 and 2). Investigations have identified specific nucleotides in the 5' noncoding region and elsewhere in the genome as critical for poliovirus neurovirulence. These manipulations have been especially informative given the relatively small size of the picornavirus genome and the large amount of molecular and structural information that is presently available regarding poliovirus and other picornaviruses.The study of Theiler murine encephalomyelitis viruses (TMEVs), a group of mouse picornaviruses most similar at the sequence level to cardioviruses, provides a valuable model system to investigate neurovirulence. One important feature ofTMEVs is that the mouse serves as both the natural and the experimental host. Another special advantage of the TMEV model relates to the natural division of TMEV strains into two subgroups on the basis of their differing biological activities (3, 4). The GDVII strain and other members of the GDVII subgroup of TMEVs are highly neurovirulent; intracerebral inoculation of a weanling mouse with one plaqueforming unit (pfu) causes an acute, fatal polioencephalomyelitis. In contrast, the DA strain and other members of the TO subgroup of TMEVs are less neurovirulent and produce a different disease following intracerebral inoculation...

The DA strain and other members of the TO subgroup of Theiler's murine encephalomyelitis viruses cause a persistent demyelinating infection, whereas the GDVII strain and other GDVII subgroup strains cause an acute lethal polioencephalomyelitis. We generated an infectious DA cDNA clone inserted into a transcription vector. Virus derived from transfection of transcripts produced a demyelinating disease indistinguishable from that of wild-type virus. The infectious clone provides a critical reagent for the production of interstrain recombinant viruses to help identify genetic loci responsible for the biological activities of the strains.

No abstract

The peptidic compound, N-acetyl-Arg-Lys-Lys-Arg-Arg-Gln-Arg-Arg-Arg-Cys(biotin)-NH2 (Tat10-biotin), contains the 9-amino acid sequence from the basic domain of the Tat protein responsible for specific interaction with TAR RNA. The cysteine residue provides an attachment site for biotin, which acts as a cellular uptake enhancer. Tat10-biotin binds a fragment of TAR RNA (deltaTAR) avidly and specifically, as measured in an electrophoretic gel shift assay. Tat10-biotin inhibited tat gene-induced expression of a stably transfected chloramphenicol acetyl transferase (CAT) reporter gene linked to the HIV-1 long terminal repeat (LTR) in a model cell assay, but did not inhibit phorbol ester-induced expression of CAT, thereby demonstrating a Tat-dependent mechanism of inhibition. Inhibition of HIV-1 replication after acute infection of MT2 cells was demonstrated by absence of HIV-induced syncytium formation and cytotoxicity, as well as by suppression of reverse transcriptase production. These results suggest that a peptide or peptide mimetic capable of competing with the TAR RNA-binding domain of Tat protein might be useful as a therapeutic agent for AIDS.