A gorilla reservoir for human T-lymphotropic virus type 4

Abstract

Of the seven known species of human retroviruses only one, human T-cell lymphotropic virus type 4 (HTLV-4), lacks a known animal reservoir. We report the largest screening for simian T-cell lymphotropic virus (STLV-4) to date in a wide range of captive and wild non-human primate (NHP) species from Cameroon. Among the 681 wild and 426 captive NHPs examined, we detected STLV-4 infection only among gorillas by using HTLV-4-specific quantitative polymerase chain reaction. The large number of samples analyzed, the diversity of NHP species examined, the geographic distribution of infected animals relative to the known HTLV-4 case, as well as detailed phylogenetic analyses on partial and full genomes, indicate that STLV-4 is endemic to gorillas, and that rather than being an ancient virus among humans, HTLV-4 emerged from a gorilla reservoir, likely through the hunting and butchering of wild gorillas. Our findings shed further light on the importance of gorillas as keystone reservoirs for the evolution and emergence of human infectious diseases and provide a clear course for preventing HTLV-4 emergence through management of human contact with wild gorillas, the development of improved assays for HTLV-4/STLV-4 detection and the ongoing monitoring of STLV-4 among gorillas and for HTLV-4 zoonosis among individuals exposed to gorilla populations.

High Prevalences and a Wide Genetic Diversity of Simian Retroviruses in Non-human Primate Bushmeat in Rural Areas of the Democratic Republic of Congo

“…Further screening did not reveal STLV-2 in monkeys from DRC. Similarly, STLV-4 was recently identified in gorillas (LeBreton et al 2014), but was not observed in NHP from our study. Prevalences varied also per species, ranging here from 5% in De Brazza and wolf's monkeys to 40% in Allen's swamp monkeys.…”

“…The four HTLV types, 1 to 4, in humans have each simian counter-parts (STLV-1 to 4) (Le Breton et al 2014; Gessain 2011; Gessain et al 2013). HTLV-1 and 2 are relatively widespread and are estimated to infect around 20 million people, but HTLV-3 and HTLV-4 have only been documented in a handful of indivuduals in central Africa (Gessain et al 2012; Mahieux et al 2011; Richard et al 2016).…”

The United States Agency for International Development Emerging Pandemic Threats PREDICT Project—Global Detection of Emerging Wildlife Viral Zoonoses

“…[19][20][21][22][23][24] As well, PREDICT researchers found strong evidence for western lowland gorillas (Gorilla gorilla gorilla) as the nonhuman primate reservoir for Human T-lymphotropic virus in western Africa, and discovered a new simian immunodeficiency virus strain in a naturally infected chimpanzee (Pan troglodytes troglodytes) with AIDS-like symptoms. 25,26 Hepatitis B virus (HBV) was found to be circulating among gorillas and chimpanzees and among subspecies of chimpanzees, refuting the previously held assumption that HBV genotypes are host-specific, with implications for the potential for spillover in this group of viruses. 27 Furthermore, PREDICT documented anthropozoonoses-human to primate transmission of viruses-including a human metapneumovirus that caused fatal respiratory disease in wild mountain gorillas (Gorilla beringei beringei) and human herpes simplex-1 virus that caused classic stomatitis in confiscated eastern lowland gorillas (Gorilla beringei graueri).…”

Infection with human retroviruses other than HIV-1: HIV-2, HTLV-1, HTLV-2, HTLV-3 and HTLV-4

“…A decade later, some cases of humans carrying HTLV-3 and 4 were also described in Cameroon, and although the epidemiology of these two viruses has not been fully studied, it is hypothesized that they might be widespread in Central Africa, although with low prevalence rates [128,129]. Finally in 2014, STLV-4, the simian counterpart of HTLV-4, was described in a gorilla from Cameroon [130]. Genetic homology of HTLV-3 and 4 with HTLV-1 is high, as they share the same gene structure (gag, pro, pol, env, tax and rex genes), suggesting that these viruses might also share the same pathogenicity mechanisms and routes of transmission [131].…”