We report the first full-length sequence of an endogenous amphibian retrovirus derived from the African clawed toad Xenopus laevis. The virus, termed Xen1, has one of the largest endogenous retroviral genomes described to date of over 10 kb in length and it also has a relatively complex genomic organisation consisting of LTR-orf1, orf2, gag, pol, env-LTR. Orfs 1 and 2 are novel, duplicated genes of unknown function. Phylogenetic analysis indicates that Xen1 is most closely related to the epsilon -retroviruses WDSV and WEHV types 1 and 2, which are large, complex exogenous retroviruses present within Walleye fish.

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One of the top species in the aquaculture sector, known as striped catfish or Pangasianodon hypophthalmus, is an important and valuable freshwater fish in many countries. Due to the high demand for this species, their number has declined to "threatened" levels.  Hence, the purpose of this study is to analyse the genetic variation of wild and cultured striped catfish collected from five producers in Asian countries; Thailand, Vietnam, Indonesia, India, and Philippines, by using mitochondrial DNA partial region data sequence; CO1 and cytochrome b gene. Population analyses using 395 base pairs length for CO1 and 275 base pairs length of cytochrome b partial region nucleotide sequence have shown no significance difference between wild and cultured striped catfish. Vietnam species had shown a wide range of genetic distance of the intrapopulation compared with other countries in the range of 0.000-0.040 for CO1 gene and 0.003-0.008 for cytochrome b gene. The Neighbour-joining method has also been used to construct phylogenetic trees using CO1 gene; the tree formed few subclades with mixed populations, and the tree using cytochrome b showed only Vietnam species divided into a few sub-populations. For the other four countries, Thailand, Indonesia, India, and Philippines were in the same group. Hence, this study's findings may provide a reference for inter and intra-relationships of P. hypophthalmus that may help in the aquaculture activity of this striped catfish.

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Lentiviruses (genus Lentivirus) are complex retroviruses that infect a broad range of mammals, including humans. Unlike many other retrovirus genera, lentiviruses have only rarely been incorporated into the mammalian germline. However, a small number of endogenous retrovirus (ERV) lineages have been identified, and these rare genomic “fossils” can provide crucial insights into the long-term history of lentivirus evolution. Here, we describe a previously unreported endogenous lentivirus lineage in the genome of the South African springhare (Pedetes capensis), demonstrating that the host range of lentiviruses has historically extended to rodents (order Rodentia). Furthermore, through comparative and phylogenetic analysis of lentivirus and ERV genomes, considering the biogeographic and ecological characteristics of host species, we reveal broader insights into the long-term evolutionary history of the genus.