Impact of Zika Virus Emergence in French Guiana: A Large General Population Seroprevalence Survey.

BACKGROUND: Since the identification of Zika virus (ZIKV) in Brazil in May 2015, the virus has spread throughout the Americas. However, ZIKV burden in the general population in affected countries remains unknown. METHODS: We conducted a general population survey in the different communities of French Guiana through individual interviews and serologic survey during June-October 2017. All serum samples were tested for anti-ZIKV immunoglobulin G antibodies using a recombinant antigen-based SGERPAxMap microsphere immunoassay, and some of them were further evaluated through anti-ZIKV microneutralization tests. RESULTS: The overall seroprevalence was estimated at 23.3% (95% confidence interval [CI], 20.9%-25.9%) among 2697 participants, varying from 0% to 45.6% according to municipalities. ZIKV circulated in a large majority of French Guiana but not in the most isolated forest areas. The proportion of reported symptomatic Zika infection was estimated at 25.5% (95% CI, 20.3%-31.4%) in individuals who tested positive for ZIKV. CONCLUSIONS: This study described a large-scale representative ZIKV seroprevalence study in South America from the recent 2015-2016 Zika epidemic. Our findings reveal that the majority of the population remains susceptible to ZIKV, which could potentially allow future reintroductions of the virus

Reconstructing Mayaro virus circulation in French Guiana shows frequent spillovers

Funder: This study was supported by the “European Regional Development Fund” under EPI-ARBO grant agreement (GY0008695), the “Regional Health Agency of French Guiana”, the “National Center of Spatial Studies”. CF acknowledges funding from Calmette and Yersin allocated by the “Pasteur Institut Department of International Affairs”. N.H. and S.C. acknowledge financial support from the AXA Research Fund, the Investissement d’Avenir program, the Laboratoire d’Excellence Integrative Biology of Emerging Infectious Diseases program (Grant ANR-10-LABX-62-IBEID), the Models of Infectious Disease Agent Study of the National Institute of General Medical Sciences, the INCEPTION project (PIA/ANR-16-CONV-0005), the European Union’s Horizon 2020 research and innovation programme under ZIKAlliance grant agreement No 734548.Abstract: Characterizing the circulation of Mayaro virus (MAYV), an emerging arbovirus threat, is essential for risk assessment but challenging due to cross-reactivity with other alphaviruses such as chikungunya virus (CHIKV). Here, we develop an analytical framework to jointly assess MAYV epidemiology and the extent of cross-reactivity with CHIKV from serological data collected throughout French Guiana (N = 2697). We find strong evidence of an important sylvatic cycle for MAYV with most infections occurring near the natural reservoir in rural areas and in individuals more likely to go to the forest (i.e., adult males) and with seroprevalences of up to 18% in some areas. These findings highlight the need to strengthen MAYV surveillance in the region and showcase how modeling can improve interpretation of cross-reacting assays

Spatial Distribution and Burden of Emerging Arboviruses in French Guiana.

Despite the health, social and economic impact of arboviruses in French Guiana, very little is known about the extent to which infection burden is shared between individuals. We conducted a large multiplexed serological survey among 2697 individuals from June to October 2017. All serum samples were tested for IgG antibodies against DENV, CHIKV, ZIKV and MAYV using a recombinant antigen-based microsphere immunoassay with a subset further evaluated through anti-ZIKV microneutralization tests. The overall DENV seroprevalence was estimated at 73.1% (70.6-75.4) in the whole territory with estimations by serotype at 68.9% for DENV-1, 38.8% for DENV-2, 42.3% for DENV-3, and 56.1% for DENV-4. The overall seroprevalence of CHIKV, ZIKV and MAYV antibodies was 20.3% (17.7-23.1), 23.3% (20.9-25.9) and 3.3% (2.7-4.1), respectively. We provide a consistent overview of the burden of emerging arboviruses in French Guiana, with useful findings for risk mapping, future prevention and control programs. The majority of the population remains susceptible to CHIKV and ZIKV, which could potentially facilitate the risk of further re-emergences. Our results underscore the need to strengthen MAYV surveillance in order to rapidly detect any substantial changes in MAYV circulation patterns

Seroprevalence of anti-SARS-CoV-2 IgG at the first epidemic peak in French Guiana, July 2020.

Funder: National Research AgencyFunder: Regional Health Agency of French GuianaFunder: Institut Pasteur Urgence COVID-19 fundraisingBACKGROUND: While Latin America has been heavily affected by the pandemic, only a few seroprevalence studies have been conducted there during the first epidemic wave in the first half of 2020. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was performed between 15 July 2020 and 23 July 2020 among individuals who visited 4 medical laboratories or 5 health centers for routine screening or clinical management, with the exception of symptomatic suggestive cases of covid-19. Samples were screened for the presence of anti-SARS-CoV-2 IgG directed against domain S1 of the SARS-CoV-2 spike protein using the anti-SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) from Euroimmun. CONCLUSIONS/SIGNIFICANCE: The overall seroprevalence was 15.4% [9.3%-24.4%] among 480 participants, ranging from 4.0% to 25.5% across the different municipalities. The seroprevalence did not differ according to gender (p = 0.19) or age (p = 0.51). Among SARS-CoV-2 positive individuals, we found that 24.6% [11.5%-45.2%] reported symptoms consistent with COVID-19. Our findings revealed high levels of infection across the territory but a low number of resulting deaths, which can be explained by French Guiana's young population structure

Implication des canaux calciques TRP dans les phénomènes de prolifération hépatocytaire

Les cellules des vertébrés ont développé un système intracellulaire de régulation qui utilise les ions calciques (Ca2+) pour contrôler de nombreux phénomènes physiologiques tels la prolifération cellulaire. Le fait que la croissance cellulaire dépende du Ca2+ extracellulaire suggère que l'entrée de Ca2+ joue un rôle important lors des événements mitogéniques. L'exacte nature moléculaire des canaux impliqués dans cette entrée reste encore matière à débats. Les gènes des canaux TRP (Transient Receptor Potential) encodent pour une vingtaine de canaux plus ou moins sélectifs au calcium. La sous-famille des TRPC comprend 6 membres chez l'homme dont certains, comme TRPC1 et TRPC6, ont déjà été impliqués dans les phénomènes de prolifération (Golovina, Platoshyn et al. 2001; Sweeney, Yu et al. 2002). Le criblage des ADNc codant pour les TRP dans des foies sains et tumoraux, chez l'homme et chez la souris, nous a permis de déterminer que TRPC6 est plus particulièrement impliqué dans les phénomènes de prolifération dans ce tissu. Nous avons développé un anticorps spécifique afin de suivre l'expression et la localisation de la protéine TRPC6. Chez la souris XVIInc/Z, l'induction chimique de tumeurs hépatiques, s'accompagne de l'expression du canal membranaire TRPC6 au niveau de la zone tumorale. L'étude des courbes de croissance de différentes lignées surexprimant stablement le canal TRPC6, l'utilisation de petits ARN interférents dirigés contre TRPC6 et la mesure de l'entrée de calcium dans ces conditions, nous ont permis de définir la relation entre influx calcique et prolifération cellulaire. Ces travaux montrent que le canal TRPC6 humain est un acteur de l'entrée capacitative, elle-même impliquée dans les phénomènes de prolifération hépatocytaire.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Kinetics of Zika Viral Load in Semen

International audienceTo the edito

Capacitative calcium entry and transient receptor potential canonical 6 expression control human hepatoma cell proliferation

International audienceStore-operated calcium entry (SOCE) is the main Ca 2؉ influx pathway involved in controlling proliferation of the human hepatoma cell lines Huh-7 and HepG2. However, the molecular nature of the calcium channels involved in this process remains unknown. Huh-7 and HepG2 cells express transient receptor potential canonical 1 (TRPC1) and TRPC6, as well as STIM1 and Orai1, and these 4 channels are the most likely candidates to account for the SOCE in these cells. We generated stable TRPC6-overexpressing or TRPC6-knockdown Huh-7 clones, in which we investigated correlations between the presence of the protein, the rate of cell proliferation, and SOCE amplitude. TRPC6-overexpressing Huh-7 cells proliferated 80% faster than did untransfected cells and their SOCE amplitude was 160% higher. By contrast, proliferation rate was 50% lower and SOCE amplitude 85% lower in TRPC6-knockdown clones than in untransfected cells. OAG (olyl acetyl glycerol)-induced calcium entry was similar in all cells, and small interfering RNA (siRNA) against TRPC1 had no effect on SOCE amplitude, highlighting the relationship among SOCE, TRPC6 and cell proliferation in Huh-7 cells. SOCE amplitude was reduced by STIM1 and Orai1 knockdowns, suggesting possible cooperation between these proteins and TRPC6 in these cells. Endothelial growth factor and hepatocyte growth factor increased TRPC6 expression and SOCE amplitude in Huh-7 cells, and cyclin D1 expression was decreased by STIM1, Orai1, and TRPC6 knockdowns. Conclusion: TRPC6 was very weakly expressed in isolated hepatocytes from healthy patients and expressed more strongly in tumoral samples from the liver of a cancer patient, strongly supporting a role for these calcium channels in liver oncogenesis

Coxsackievirus A24 Variant Associated with Acute Haemorrhagic Conjunctivitis Cases, French Guiana, 2017

International audienc

Sévérité des grippes saisonnières post-pandémiques en milieu tropical de 2012 à 2015 (PADS02-06).

International audienc

The use of serum spotted onto filter paper for diagnosing and monitoring Chikungunya virus infection

AbstractBackgroundThe recent emergence of Chikungunya Virus (CHIKV) in the Americas constitutes a major public health problem on this continent, where the mosquito vector is widespread. The rapid diagnosis of suspected cases is essential for the monitoring and control of this ongoing outbreak. However, this requires reliable tools that are difficult to establish in areas without specialized laboratories.ObjectivesThe aim was to evaluate the performances of serum samples spotted onto filter paper for molecular and serological diagnosis of Chikungunya infection.Study designAnalyses were performed from frozen sera and serum spotted onto filter paper provided from 121 Chikungunya suspected cases collected at a biological laboratory on Saint-Martin Island.ResultsThis approach performed well in comparisons with standard methods, with a sensitivity of 100% and a specificity of 93.6% for the combined technical approaches (RT-PCR and serological results). Comparisons of serum samples spotted onto filter paper and frozen samples showed a concordance rate of 94.8% in molecular tests and 98.2% in serological tests.ConclusionsThis simple sampling technique could overcome the problems of the lack of efficient CHIKV diagnosis tools in remote regions, providing good results regardless of the molecular or serological approach used. This simple filter paper-based method can be used to diagnose both chikungunya and dengue infections, as previously demonstrated following transport at ambient temperature to specialized laboratories. Given the set-up costs and high performance of this method, it could be recommended for the monitoring and control of Chikungunya virus expansion in the Americas and in other affected regions