Le rétrovirus humain oncogène HTLV-1 : épidémiologie descriptive et moléculaire, origine, évolution et aspects diagnostiques et maladies associées

Abstract

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) was the first oncogenic human retrovirus discovered in 1980. It is estimated that around 10-20 million people are infected with HTLV-1 worldwide. However, HTLV-1 is not a ubiquitous virus. Indeed, HTLV-1 is present throughout the world with clusters of high endemicity including mainly southern Japan, the Caribbean region, parts of South America and intertropical Africa, with foci in the Middle East and Australia. The origin of this puzzling geographical repartition is probably linked to a founder effect in certain human groups. In the high endemic areas, 0.5 to 50% of the people have antibodies against HTLV-1 antigens. HTLV-1 seroprevalence increases with age, especially in women. HTLV-1 has 3 modes of transmission: mother to child, mainly through prolonged breastfeeding (> 6 months); sexual, mainly but not exclusively occurring from male to female; and by blood products contaminated by infected lymphocytes. HTLV-1 is mainly the etiological agent of two very severe diseases: a malignant T CD4+ cell lymphoproliferation of very poor prognosis, named adult T-cell leukemia/lymphoma (ATLL), and a chronic neuro-myelopathy named tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). HTLV-1 is also associated with rare anterior uveitis, infective dermatitis and myositis in some high HTLV-1 endemic areas. The repartition of the different molecular subtypes or genotypes is mainly linked to the geographical origin of the infected persons but not to the associated pathology. HTLV-1 possesses a remarkable genetic stability probably linked to viral amplification via clonal expansion of infected cells rather than by reverse transcription. This stability can be used as a molecular tool to gain better insights into the origin, evolution and modes of dissemination of HTLV-1 and infected populations. HTLV-1 originated in humans through interspecies transmission from STLV-1, a very closely related retrovirus, highly endemic in several populations of apes and Old World monkeys.

Seroprevalence of viral infections in captive rhesus and cynomolgus macaques

“…Our results indicate that infection by the herpesviruses CMV, LCV and RRV and by the retrovirus SFV is frequent and often acquired early in life in the macaque population studied. These results are generally in keeping with published data (Chu et al, 1971;Ishida and Varavudhi, 1992;Ryan and Rose, 2013;Vogel et al, 1994;Calattini et al, 2006;Jones-Engel et al, 2007Muniz et al, 2015) although the macaque colony in Gibraltar was found to be CMV negative, for reasons not fully understood . Transmission is thought to occur via the oral route and/or through bites and scratches.…”

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

“…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).…”

Human T-cell lymphotropic virus-1 infection: three infected generations in the same family

“…The majority of carriers are asymptomatic, with only 3-7% of affected people presenting with clinical manifestations (2) . The clinical spectrum of the disease encompasses infective dermatitis (IDH), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/ TSP), and adult T-cell leukemia lymphoma (ATLL) (3) .…”