Retrovirus insertion into herpesvirus in vitro and in vivo.

Abstract

Retroviruses and herpesviruses are naturally occurring pathogens of humans and animals. Coinfection of the same host with both these viruses is common. We report here that a retrovirus can integrate directly into a herpesvirus genome. Specifically, we demonstrate insertion of a nonacute retrovirus, reticuloendotheliosis virus (REV), into a herpesvirus, Marek disease virus (MDV). Both viruses are capable of inducing T lymphomas in chickens and often coexist in the same animal. REV DNA integration into MDV occurred in a recently attenuated strain of MDV and in a short-term coinfection experiment in vitro. We also provide suggestive evidence that REV has inserted into pathogenic strains of MDV in the past. Sequences homologous to the REV long terminal repeat are found in oncogenic MDV but not in nononcogenic strains. These results raise the possibility that retroviral information may be transmitted by herpesvirus and that herpesvirus expression can be modulated by retroviral elements. In addition, retrovirus may provide a useful tool to characterize herpesviral function by insertional mutagenesis.

Reticuloendotheliosis Virus Sequences within the Genomes of Field Strains of Fowlpox Virus Display Variability

“…This event, however, has usually resulted in only a solitary REV LTR or one having a 23-bp repeated sequence at its 5Ј terminus that is retained during subsequent replication of the altered herpesviruses (10,12,14). In contrast, when the recipient was the herpesvirus of turkeys, a stable integrant having an intact provirus was found in addition to ones containing individual proviruses with internal deletions (11).…”

“…Although no genetic exchange between these viruses has been documented, it should be noted that homologs of several FPV genes are present in the genome of another avian herpesvirus, Marek's disease virus (4). Moreover, short nucleotide stretches exhibiting Ͼ70% homology with the R and U3 regions of the long terminal repeat (LTR) of the avian retrovirus reticuloendotheliosis virus (REV) have been found in the DNA of two serotype I oncogenic strains of Marek's disease virus (10). Likewise, remnants of the REV LTR have been retained in the genomes of all FPV vaccine strains so far examined (9,15,22).…”

Complete Genome Sequence of a Recombinant Marek's Disease Virus Field Strain with One Reticuloendotheliosis Virus Long Terminal Repeat Insert

“…The GX0101 strain in this report was the first recombinant MDV field strain containing the reticuloendotheliosis virus (REV) long terminal repeat (LTR) insert (17), and it is a very virulent MDV with higher horizontal transmission ability (1,12). However, other recombinant MDV strains with the REV LTR, such as RM1, obtained in cell cultures were attenuated and did not cause tumors (2,3,15).…”

Detection of reticuloendotheliosis virus infection using the polymerase chain reaction

“…Additional applications of the PCR include: retrospective diagnosis using DNA recovered from formalin-fixed, paraffin-embedded tissue sections (Kallio et al, 1991); certification of avian vaccines, detection of REV proviral insertion into the genomes of MDV (Isfort et al, 1992); and other avian viruses and qualification of specific pathogen-free flocks. The possible residence of proviral REV sequences in other avian species or parasites that infect chickens can also be addressed using the PCR.…”