Foamy viruses are complex retroviruses whose replication strategy resembles that of conventional retroviruses. However, foamy virus replication also resembles that of hepadnaviruses in many respects. Because hepadnaviruses replicate in an integrase-independent manner, we were interested in investigating the characteristics of human foamy virus (HFV) integration. We have shown that HFV requires ...

The human genome harbors numerous distinct families of so-called human endogenous retroviruses (HERV) which are remnants of exogenous retroviruses that entered the germ line millions of years ago. We describe here the hitherto little-characterized betaretrovirus HERV-K(HML-5) family (named HERVK22 in Repbase) in greater detail. Out of 139 proviruses, only a few loci represent full-length provir...

The recent development and advancement of next-generation sequencing (NGS) technologies have enabled the characterization of the human genome at extremely high resolution. In the retrovirology field, NGS technologies have been applied to integration-site analysis and deep sequencing of viral genomes in combination with PCR amplification using virus-specific primers. However, virus-specific prim...

We examined 14 different feline leukemia virus proviruses from the productively infected human cell line RD(FeLV)-2 after cloning in the modified lambda vector Charon 4A. Each isolate was characterized by restriction digestion and Southern blot analysis. The DNA of each isolate was tested for competence to express virus after uptake by sensitive animal cells (transfection). All but one isolate ...

We have studied whether the origin of retroviral onc genes, by transduction of sequences from cellular proto-onc genes, involves DNA or RNA recombination. By using altered Harvey sarcoma proviruses as models for transduction intermediates, we have investigated the mechanism of regeneration of transforming virus from truncated proviruses with only a single 5' long terminal repeat (LTR) but with ...

Bovine leukemia virus (BLV) is a retrovirus responsible for lymphoproliferative disorders in cattle. Although infections of BLV in animals are well known, little is known about its capacity to infect humans. This study investigated the presence of anti-BLV antibodies and BLV proviruses in human and cattle samples. An indirect enzyme-linked immunosorbent assay (ELISA) was used to detect anti-BL...

Bovine leukemia virus (BLV) is a retrovirus responsible for lymphoproliferative disorders in cattle. Although infections of BLV in animals are well known, little is known about its capacity to infect humans. This study investigated the presence of anti-BLV antibodies and BLV proviruses in human and cattle samples. An indirect enzyme-linked immunosorbent assay (ELISA) was used to detect anti-BL...

Human endogenous retrovirus K (HERV-K) is the most intact retrovirus in the human genome. However, no single HERV-K provirus in the human genome today appears to be infectious. Since the Gag protein is the central component for the production of retrovirus particles, we investigated the abilities of Gag from two HERV-K proviruses to support production of virus-like particles and viral infectivi...

A conserved property of retroviral proviruses is the presence of a direct repeat in the host DNA immediately flanking the viral sequence; each virus generates a repeat with a characteristic length. By sequencing the viral/host DNA junctions from five HIV-1 proviral clones, we have confirmed that integration of HIV results in the generation of a five basepair direct repeat. A target sequence in ...

The HIV-1 Vif protein counteracts the antiviral activity exhibited by the host cytidine deaminases APOBEC3G and APOBEC3F. Here, we show that defective vif alleles can readily be found in HIV-1 isolates and infected patients. Single residue changes in the Vif protein sequence are sufficient to cause the loss of Vif-induced APOBEC3 neutralization. Interestingly, not all the detected defects lead ...