Publications by authors named "Gessain A"

Foamy viruses (FVs) constitute a subfamily of retroviruses. Their envelope (Env) glycoprotein drives the merger of viral and cellular membranes during entry into cells. The only available structures of retroviral Envs are those from human and simian immunodeficiency viruses from the subfamily of orthoretroviruses, which are only distantly related to the FVs.

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  • - High seroreactivities to Ebola (EBOV) and Sudan (SUDV) orthoebolavirus antigens were found in rural populations of Cameroon, particularly among Pygmies, despite no reported outbreaks.
  • - The study did not find a direct link between the risk of NHP (nonhuman primates) bites and seroreactivity, but indicated that exposure may vary among different ethnic groups.
  • - These findings suggest a possible silent circulation of orthoebolaviruses or other unknown filoviruses in forested regions, emphasizing the need for increased surveillance and research in these areas.
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In Europe, most HTLV-1-infected individuals originate from highly endemic regions such as West Indies, sub-Saharan Africa, and South America. The only genuine endemic region for HTLV-1 in Europe is Romania where ATL series have been reported among Romanian patients. Our objective is to better understand the origin of this endemic focus based on a study of the genetic diversity of HTLV-1 in Romanians.

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Across 133 confirmed mpox zoonotic index cases reported during 1970-2021 in Africa, cases occurred year-round near the equator, where climate is consistent. However, in tropical regions of the northern hemisphere under a dry/wet season cycle, cases occurred seasonally. Our findings further support the seasonality of mpox zoonotic transmission risk.

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Background: Adult T-cell leukemia/lymphoma (ATL), one of the most aggressive cancers in the world, occurs in 5% of the 10 million people living with HTLV-1 worldwide. French Guiana, a French overseas territory in South America, is one of the highest endemic areas of HTLV-1 worldwide. Here, we describe the demographic and clinical characteristics and outcome of ATL in this area.

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  • - Infection with simian foamy viruses (SFVs) can result in lifelong infections in humans but typically do not cause severe disease or human-to-human transmission, making them an interesting case study for zoonotic retroviruses.
  • - Researchers studied neutralizing antibodies (nAbs) in SFV-infected individuals from Central Africa, focusing on the viral envelope protein's variable regions, which are crucial for nAb targeting and do not exhibit major immune escape mechanisms.
  • - Three primary regions crucial for nAb binding were identified, and they play a role in preventing the virus from changing shape or binding to human cells, effectively blocking infection.
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  • Monkeypox virus (MPXV) became a big concern in 2022, causing over 86,000 infections worldwide, and could spread more if not controlled.
  • Public health strategies like isolation and vaccination have helped, but cases are still appearing in 28 countries as of March 2023.
  • There's a need for better vaccines and treatments, more data, and international cooperation to manage the outbreak and protect vulnerable groups from getting infected.
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Previous human cases or epidemics have suggested that Monkeypox virus (MPXV) can be transmitted through contact with animals of African rainforests. Although MPXV has been identified in many mammal species, most are likely secondary hosts, and the reservoir host has yet to be discovered. In this study, we provide the full list of African mammal genera (and species) in which MPXV was previously detected, and predict the geographic distributions of all species of these genera based on museum specimens and an ecological niche modelling (ENM) method.

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Human monkeypox virus is spreading globally, and more information is required about its epidemiological and clinical disease characteristics in endemic countries. We report the investigation of an outbreak in November 2021 in Central African Republic (CAR). The primary case, a hunter, fell ill after contact with a non-human primate at the frontier between forest and savannah.

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The surface envelope glycoprotein (Env) of all retroviruses mediates virus binding to cells and fusion of the viral and cellular membranes. A structure-function relationship for the HIV Env that belongs to the Orthoretrovirus subfamily has been well established. Structural information is however largely missing for the Env of Foamy viruses (FVs), the second retroviral subfamily.

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The African continent is considered the largest high endemic area for the oncogenic retrovirus HTLV-1 with an estimated two to five million infected individuals. However, data on epidemiological aspects, in particular prevalence, risk factors and geographical distribution, are still very limited for many regions: on the one hand, few large-scale and representative studies have been performed and, on the other hand, many studies do not include confirmatory tests, resulting in indeterminate serological results, and a likely overestimation of HTLV-1 seroprevalence. For this review, we included the most robust studies published since 1984 on the prevalence of HTLV-1 and the two major diseases associated with this infection in people living in Africa and the Indian Ocean islands: adult T-cell leukemia (ATL) and tropical spastic paraparesis or HTLV-1-associated myelopathy (HAM/TSP).

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We analyzed monkeypox disease surveillance in Central African Republic (CAR) during 2001-2021. Surveillance data show 95 suspected outbreaks, 40 of which were confirmed as monkeypox, comprising 99 confirmed and 61 suspected monkeypox cases. After 2018, CAR's annual rate of confirmed outbreaks increased, and 65% of outbreaks occurred in 2 forested regions bordering the Democratic Republic of the Congo.

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The Vanuatu archipelago served as a gateway to Remote Oceania during one of the most extensive human migrations to uninhabited lands ∼3,000 years ago. Ancient DNA studies suggest an initial settlement by East Asian-related peoples that was quickly followed by the arrival of Papuan-related populations, leading to a major population turnover. Yet there is uncertainty over the population processes and the sociocultural factors that have shaped the genomic diversity of ni-Vanuatu, who present nowadays among the world's highest linguistic and cultural diversity.

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  • Zika virus (ZIKV), a mosquito-borne flavivirus, emerged in the Pacific in 2007 and has since spread to the Americas, being mainly asymptomatic but potentially causing severe neurological issues.
  • Current research has discovered two peptides from claudin proteins (CL7.1 and CL1.1) that effectively inhibit ZIKV infection in human cell lines by disrupting viral E-mediated membrane fusion.
  • Additionally, CL1.1 was found to also block infection from yellow fever and Japanese encephalitis viruses, indicating potential for developing new antiviral therapies targeting multiple flaviviruses.
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Background: A link between chronic inflammation and several noncommunicable diseases (NCDs) has been established. Although chronic infection with the human T-cell leukemia virus type 1 (HTLV-1) is the recognized cause of several inflammatory diseases and these are associated with a high number of HTLV-1-infected cells in peripheral blood (proviral load [PVL]), possible interactions between PVL and NCDs have not been studied at a community level.

Methods: Adult Aboriginal residents of 7 remote communities were invited to complete a health survey between 25 August 2014 and 30 June 2018.

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  • - Central Africa, particularly Cameroon, has a high prevalence of HTLV-1, yet no preventive measures are in place to combat its transmission, which can occur through various means such as sexual contact, mother-to-child, and contaminated blood products.
  • - A study conducted from 2019 to 2021 found that out of 3,400 participants, the HTLV-1 infection rate was 1.1%, with higher risks associated with factors like Pygmy ethnicity, a history of surgery, and bites from nonhuman primates.
  • - The findings indicate both iatrogenic (from healthcare practices) and zoonotic (from animals) transmission of HTLV-1, highlighting the need for further research to develop public health
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  • Human T-cell lymphotrophic virus type-1 (HTLV-1) and human immunodeficiency virus (HIV-1) co-infection is common in Gabon, and co-infected individuals tend to progress more rapidly to AIDS.
  • * The study involved 299 individuals, revealing a 7.7% prevalence of HTLV-1 infection, with women and older age being risk factors for co-infection.
  • * Results indicated higher CD4+ cell counts and a lower HIV-1 viral load in co-infected individuals compared to those with just HIV-1, emphasizing the need for improved prevention and management strategies for co-infections.
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Monkeypox is an emerging and neglected zoonotic disease whose number of reported cases has been gradually increasing in Central Africa since 1980. This disease is caused by the monkeypox virus (MPXV), which belongs to the genus Orthopoxvirus in the family Poxviridae. Obtaining molecular data is particularly useful for establishing the relationships between the viral strains involved in outbreaks in countries affected by this disease.

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Zika virus (ZIKV) is a mosquito-borne RNA virus belonging to the genus of the family. During the 60 years following its discovery in 1947, ZIKV caused little concern for public health as the associated infection was reported as mostly asymptomatic or inducing mild symptoms. However, since 2013, severe neurological symptoms have been associated with ZIKV infection, compelling the World Health Organization to declare a Public Health Emergency of International Concern.

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  • Zoonotic simian foamy viruses (SFV) lead to lifelong infections in humans but do not cause severe health issues or human-to-human transmission.
  • The study investigated the immune response of SFV-infected individuals, focusing on their ability to produce neutralizing antibodies against both cell-free virus and potential cell-to-cell transmission.
  • Despite finding that these antibodies can bind to the infected cells, the research concluded that they do not prevent the cell-to-cell spread of SFV, indicating different mechanisms of viral transmission.
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Objective: A single study conducted about three decades ago on hepatitis D virus (HDV) infection among Baka pygmies in Cameroon reported a very high anti-HDV antibodies prevalence of 46%, but HDV genetic diversity has not been studied in this population. The genetic diversity of strains from endemic ancient populations may help to understand the origin and evolutionary history of viruses. This study aimed to investigate the HDV seroprevalence and the genetic diversity in three remote Cameroonian Pygmies with chronic HBV infection.

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Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences.

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Infection with the human T cell leukaemia virus type 1 (HTLV-1) subtype C is endemic among Aboriginal people in central Australia. To provide insights into the risk factors for transmission, we conducted the first large-scale, community-based prevalence study in seven remote Aboriginal communities. Residents >2 years old were invited to participate in the study between August 2014 and June 2018.

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