HIV-1, the cause of AIDS, is composed of four phylogenetic lineages, groups M, N, O, and P, each of which resulted from an independent cross-species transmission event of simian immunodeficiency viruses (SIVs) infecting African apes. Although groups M and N have been traced to geographically distinct chimpanzee communities in southern Cameroon, the reservoirs of groups O and P remain unknown. Here, we screened fecal samples from western lowland (n = 2,611), eastern lowland (n = 103), and mountain (n = 218) gorillas for gorilla SIV (SIVgor) antibodies and nucleic acids. Despite testing wild troops throughout southern Cameroon (n = 14), northern Gabon (n = 16), the Democratic Republic of Congo (n = 2), and Uganda (n = 1), SIVgor was identified at only four sites in southern Cameroon, with prevalences ranging from 0.8–22%. Amplification of partial and full-length SIVgor sequences revealed extensive genetic diversity, but all SIVgor strains were derived from a single lineage within the chimpanzee SIV (SIVcpz) radiation. Two fully sequenced gorilla viruses from southwestern Cameroon were very closely related to, and likely represent the source population of, HIV-1 group P. Most of the genome of a third SIVgor strain, from central Cameroon, was very closely related to HIV-1 group O, again pointing to gorillas as the immediate source. Functional analyses identified the cytidine deaminase APOBEC3G as a barrier for chimpanzee-to-gorilla, but not gorilla-to-human, virus transmission. These data indicate that HIV-1 group O, which spreads epidemically in west central Africa and is estimated to have infected around 100,000 people, originated by cross-species transmission from western lowland gorillas.

Bats carry a great diversity of zoonotic viruses with a high-impact on human health and livestock. Since the emergence of new coronaviruses and paramyxoviruses in humans (e.g. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Nipah virus), numerous studies clearly established that bats can maintain some of these viruses. Improving our understanding on the role of bats in the epidemiology of the pathogens they harbour is necessary to prevent cross-species spill over along the wild/domestic/human gradient. In this study, we screened bat faecal samples for the presence of Coronavirus and Paramyxovirus in two caves frequently visited by local people to collect manure and/or to hunt bats in Zimbabwe. We amplified partial RNA-dependent RNA polymerase genes of Alpha and Betacoronavirus together with the partial polymerase gene of Paramyxovirus. Identified coronaviruses were related to pathogenic human strains and the paramyxovirus belonged to the recently described Jeilongvirus genus. Our results highlighted the importance of monitoring virus circulation in wildlife, especially bats, in the context of intense human-wildlife interfaces in order to strengthen prevention measures among local populations and to implement sentinel surveillance in sites with high zoonotic diseases transmission potential.