SARS-CoV-2 seroprevalence and associated factors among outpatient attendees at health facilities in different provinces in Chad.

Background: Chad with 7,698 confirmed cases of infection and 194 deaths since the beginning of the COVID-19 pandemic, is one of the African countries with the lowest reported case numbers. However, this figure likely underestimates the true spread of the virus due to the low rate of diagnosis. The high rate of asymptomatic infections reflects the reality of SARS-CoV-2 transmission in Chad.

Evidence of Zika virus circulation in human and livestock in Chad.

Zika virus (ZIKV) is a major public health problem worldwide. After several reported outbreaks, the current extent of infections caused by this orthoflavivirus in the Sahel remains to be explored. We investigated the prevalence of neutralizing antibodies against ZIKV in the general population, in HIV-infected individuals and in livestock in Chad using a seroneutralization assay that ensures high specificity level.

Diversity, geographical distribution and predictive factors of Hepatitis C virus genotypes and subtypes in Rwanda.

Background: Existing data on the prevalence of hepatitis C virus (HCV) genotypes and subtypes in Rwanda need to be strengthened. The aim of this study was to identify HCV genotypes and subtypes among HCV-infected patients, as well as their geographical distribution in Rwanda, and to identify the social and economic factors that could influence HCV epidemiology which would make it possible to target national preventive and management actions for infected patients.

Methods: This study included 560 patients with confirmed chronic HCV infection.

Predictors of COVID-19 vaccine hesitancy in Chad: A cross-sectional study.

Vaccination against the COVID-19 virus is currently the best option to combat the SARS-CoV-2 pandemic worldwide. However, in addition to logistical and economic barriers, hesitancy to be vaccinated threatens to jeopardize efforts to contain the disease. An increasing number of people in Africa are delaying or rejecting recommended vaccines.

Human innate lymphoid cell activation by adenoviruses is modified by host defense proteins and neutralizing antibodies.

Innate lymphoid cells (ILCs), the complements of diverse CD4 T helper cells, help maintain tissue homeostasis by providing a link between innate and adaptive immune responses. While pioneering studies over the last decade have advanced our understanding how ILCs influence adaptive immune responses to pathogens, far less is known about whether the adaptive immune response feeds back into an ILC response. In this study, we isolated ILCs from blood of healthy donors, fine-tuned culture conditions, and then directly challenged them with human adenoviruses (HAdVs), with HAdVs and host defense proteins (HDPs) or neutralizing antibodies (NAbs), to mimic interactions in a host with pre-existing immunity.

Th17 CD4+ T-Cell as a Preferential Target for HIV Reservoirs.

Among CD4+ T-cells, T helper 17 (Th17) cells play a sentinel role in the defense against bacterial/fungal pathogens at mucosal barriers. However, Th17 cells are also highly susceptible to HIV-1 infection and are rapidly depleted from gut mucosal sites, causing an imbalance of the Th17/Treg ratio and impairing cytokines production. Consequently, damage to the gut mucosal barrier leads to an enhanced microbial translocation and systemic inflammation, a hallmark of HIV-1 disease progression.

Syphilis diagnosis and serological response to Benzathine Penicillin G among patients attending HIV clinics in N'Djaména, Chad.

Background: Syphilis is endemic in the Sub-Saharan zone and disproportionately affects at-risk populations such as men who have sex with men, sex workers and HIV infected individuals. In this study, we measure the impact of syphilis among people living with HIV in the Republic of Chad, where no data are currently available.

Method: Outpatients attending 2 HIV clinics in N'Djamena, Republic of Chad, were tested for syphilis.

A review of 65 years of human adenovirus seroprevalence.

: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence.

Combination of metformin with sodium selenite induces a functional phenotypic switch of human GM-CSF monocyte-derived macrophages.

Objectives: We evaluated the effects of metformin (Met, 1,1‑dimethylbiguanide hydrochloride) combined or not with sodium selenite (Ss, NaSeO) on the functional activities of LPS-activated GM-CSF monocyte-derived macrophages (GM-MDM).

Materials And Methods: Human GM-MDMs from three healthy donors were treated with Met or Ss alone, or with the combination of Met and Ss, and assayed for various biological activities and cytokines expression.

Results: Met alone and Ss alone had significantly different effects on phagocytosis and killing capacities and IL-β production, but had similar effects on the downregulation of inducible nitric oxide synthase (iNOS) activity, relative nicotinamide adenine dinucleotide reduced (NADH) dehydrogenase (Complex I), intracellular free calcium ions (Ca), and on the upregulation of arginase activity.

Thymoquinone Potently Enhances the Activities of Classically Activated Macrophages Pulsed with Necrotic Jurkat Cell Lysates and the Production of Antitumor Th1-/M1-Related Cytokines.

Antitumor activity of classically activated macrophage (Mϕ) may be impaired within the tumors, spleen, and bone marrow. Thus, it is possible to boost its antitumor activity after its pulsing with necrotic tumor cell lysates combined with an adjuvant. We set out to determine the potential adjuvant effects of thymoquinone (TQ; 2-isopropyl-5-methyl-1,4-benzoquinone, CHO) on both functional activities of classically activated Mϕs, pulsed or not with necrotic Jurkat T cell line lysates (NecrJCL), and the balance of antitumor cytokines (ATCs) versus immunosuppressive cytokines (ISCs) during crosstalk with autologous human CD4 T cells.

Humoral immune response to adenovirus induce tolerogenic bystander dendritic cells that promote generation of regulatory T cells.

Following repeated encounters with adenoviruses most of us develop robust humoral and cellular immune responses that are thought to act together to combat ongoing and subsequent infections. Yet in spite of robust immune responses, adenoviruses establish subclinical persistent infections that can last for decades. While adenovirus persistence pose minimal risk in B-cell compromised individuals, if T-cell immunity is severely compromised reactivation of latent adenoviruses can be life threatening.

Immune-Complexed Adenovirus Induce AIM2-Mediated Pyroptosis in Human Dendritic Cells.

Human adenoviruses (HAdVs) are nonenveloped proteinaceous particles containing a linear double-stranded DNA genome. HAdVs cause a spectrum of pathologies in all populations regardless of health standards. Following repeat exposure to multiple HAdV types, we develop robust and long-lived humoral and cellular immune responses that provide life-long protection from de novo infections and persistent HAdV.

[Is there a risk of zoonotic disease due to adenoviruses?].

Every year brings another round of zoonotic viral infections. Usually they fall under the radar, but the occasional lethal epidemic brings another scare to the public and new urgency to the medical community. The types of these viruses (DNA vs.

Ebola virus vaccine: benefit and risks of adenovirus-based vectors.

In 2014, an outbreak of Ebola virus spread rapidly in West Africa. The epidemic killed more than 10,000 people and resulted in transmissions outside the endemic countries. WHO hopes for effective vaccines by the end of 2015.

Human coagulation factor X-adenovirus type 5 complexes poorly stimulate an innate immune response in human mononuclear phagocytes.

Unlabelled: One of the first lines of host defense against many viruses in vertebrates is the innate immune system, which detects pathogen-associated molecular patterns (PAMPs) using pathogen recognition receptors (PRR). The dynamic interactions between pathogens and hosts create, in some cases, species-specific relationships. Recently, it was shown that murine factor X (mFX)-armored human adenovirus (HAd) stimulated a mFX-Toll-like receptor 4 (TLR4)-associated response in mouse macrophages in vitro and in vivo.

A real-time PCR assay for quantification of canine adenoviral vectors.

The pre-existing humoral and cellular immunity found in the great majority of the population raises concerns about the clinical efficacy and safety of vectors derived from ubiquitous human adenovirus serotypes. To alleviate these concerns, canine adenovirus type 2 vectors (CAV-2) were developed. Owing to their extraordinary neuronal tropism and efficient axonal retrograde transport, CAV-2 vectors hold great promise for the treatment of neurodegenerative diseases.

The cell adhesion molecule "CAR" and sialic acid on human erythrocytes influence adenovirus in vivo biodistribution.

Although it has been known for 50 years that adenoviruses (Ads) interact with erythrocytes ex vivo, the molecular and structural basis for this interaction, which has been serendipitously exploited for diagnostic tests, is unknown. In this study, we characterized the interaction between erythrocytes and unrelated Ad serotypes, human 5 (HAd5) and 37 (HAd37), and canine 2 (CAV-2). While these serotypes agglutinate human erythrocytes, they use different receptors, have different tropisms and/or infect different species.

Contrasting effects of human, canine, and hybrid adenovirus vectors on the phenotypical and functional maturation of human dendritic cells: implications for clinical efficacy.

Antipathogen immune responses create a balance between immunity, tolerance, and immune evasion. However, during gene therapy most viral vectors are delivered in substantial doses and are incapable of expressing gene products that reduce the host's ability to detect transduced cells. Gene transfer efficacy is also modified by the in vivo transduction of dendritic cells (DC), which notably increases the immunogenicity of virions and vector-encoded genes.

Interferon-lambda-treated dendritic cells specifically induce proliferation of FOXP3-expressing suppressor T cells.

The lambda interferons (IFN-lambdas), also known as IL-28 and IL-29, are coexpressed with IFN-beta after Toll-like-receptor (TLR) stimulation in human monocyte-derived dendritic cells (DCs). IFN-lambda shares with type I IFNs an intracellular signaling pathway that drives the expression of a common set of genes. However, IFN-lambda signaling is initiated through a membrane receptor system distinct from that of type I IFNs.

Interferon-alpha and -beta differentially regulate osteoclastogenesis: role of differential induction of chemokine CXCL11 expression.

In humans, type I interferon (IFN) is a family of 17 cytokines, among which the alpha subtypes and the beta subtype are differentially expressed. It has been suggested that IFN-beta activates a specific signaling cascade in addition to those activated by all type I IFNs. Nevertheless, no true biological relevance for a differential activity of alpha and beta IFN subtypes has been identified so far.