Performance characteristics of Allele-Specific PCR (ASPCR) in detecting drug resistance mutations among non-B HIV-1 Variants.

Allele-Specific Polymerase Chain Reaction (ASPCR) is an affordable point-mutation assay whose validation could improve the detection of HIV-1 drug resistance mutations (DRMs) in resource-limited settings (RLS). We assessed the performance of ASPCR onforty-four non-B HIV-1 plasma samples from patients who were ARV treated in failure in N'Djamena-Chad. Viral RNA was reverse-transcribed and amplified using LightCycler® FastStart DNA MasterPLUS SYBR Green I. Detection of six major DRMs (K70R, K103N, Y181C, M184V, T215F, T215Y) was evaluated on Roche LightCycler®480 automated system (with dilutions 0.01-100%). ASPCR-results were compared to Sanger-sequencing (gold-standard). Correlations of mutation curves were excellent (R2 >0.97); all DRMs were detected with desirable mutant/wild-type threshold differences (ΔCt≥9) except K70R(ΔCtK70R=6; ΔCtK103N=13; ΔCtM184V=9; ΔCtT215F=12; ΔCtT215Y=12; ΔCtY181C=9) and positive controls were below required thresholds. Also, ASPCR reproducibility on DRMs was assessed by using dilutions of intra-assay and inter-assay coefficient of variations respectively with a threshold of less than 50(i.e.<0.50 variation) which are;: K70R (0.02-0.28 vs. 0.12-0.37), K103N (0.08-0.42 vs. 0.12-0.37), Y181C (0.12-0.39 vs. 0.31-0.37), M184V (0.13-0.39 vs. 0.23-0.42), T215F (0.05-0.43 vs. 0.04-0.45) and T215Y (0.13-0.41 vs. 0.19-0.41). DRM detection-rate by ASPCR vs Sanger was respectively: M184V (63.6% vs. 38.6%); T215F (18.1% vs. 9.1%); T215Y (6.8% vs. 2.3%); K70R (4.5% vs. 2.3%). K103N (22.7% vs. 13.6%); Y181C (13.6% vs. 11.4%). Correlations of mutation curves were excellent (R2 >0.97); all DRMs were detected with desirable mutant/wild-type threshold differences (ΔCt≥9) except K70R(ΔCtK70R=6; ΔCtK103N=13; ΔCtM184V=9; ΔCtT215F=12; ΔCtT215Y=12; ΔCtY181C=9) and positive controls were below required thresholds. Also, ASPCR reproducibility on DRMs was assessed by using dilutions of intra-assay and inter-assay coefficient of variations respectively with a threshold of less than 50(i.e.<0.50 variation) which are;: K70R (0.02-0.28 vs. 0.12-0.37), K103N (0.08-0.42 vs. 0.12-0.37), Y181C (0.12-0.39 vs. 0.31-0.37), M184V (0.13-0.39 vs. 0.23-0.42), T215F (0.05-0.43 vs. 0.04-0.45) and T215Y (0.13-0.41 vs. 0.19-0.41). DRM detection-rate by ASPCR vs Sanger was respectively: M184V (63.6% vs. 38.6%); T215F (18.1% vs. 9.1%); T215Y (6.8% vs. 2.3%); K70R (4.5% vs. 2.3%). K103N (22.7% vs. 13.6%); Y181C (13.6% vs. 11.4%). ASPCR appears more efficient for detecting DRMs on diverse HIV-1 non-B circulating in RLS like Chad.

Presence of neutralizing SARS-CoV-2 antibodies in asymptomatic population of N'Djamena, Chad.

INTRODUCTION: Neutralizing antibodies (NAbs) are an important specific defence against viral infections, as these antibodies bind to specific receptor(s) and block the viral entry. NAbs assessments are therefore useful in determining individual or herd immunity to SARS-CoV-2. This study aims to deepen the investigation by assessing the positivity rate of neutralizing anti-spike antibodies to understand the real protection of the studied population against SARS-CoV-2. METHODS: This study involved 260 plasma samples from a larger cohort of 2,700 asymptomatic volunteer donors, enrolled between August and October 2021 in health facilities of N'Djamena. In this study four different kits and techniques including the pseudotype assay have been used and compared with detect the SARS-CoV-2 antibodies. Pseudotyped vesicular stomatitis virus (VSV), was used both the identify and measure the NAbs that to evaluate the performance of two cheaper and easy to use commercial kits, specific for the detection of receptor-binding domain antibodies (anti-RBD) against the SARS-CoV-2 spike protein. RESULTS: The VSV spike neutralization assay showed that 59.0% (n = 59) samples were positive for NAbs with titers ranging from 1:10 to 1:4800. While 23 out the 41 negative NAbs samples were detected positive using anti-RBD (Abbott) test. Furthermore, a direct and significant strong correlation was found between NAbs and anti-RBD, specifically with Abbott kit. Taken together, the Roche and Abbott methods indicated agreement at the high concentrations of antibodies with the VSV-pseudovirus method. Abbott and Roche indicated a good sensitivity, but the Abbott system test appeared to have better specificity than the Roche test. CONCLUSION: Our findings indicated a high presence of NAbs against SARS-CoV-2 spike protein among asymptomatic individuals in N'Djamena. This could be one of the reasons for the low severity of Covid-19 observed in this area, given the key role of NAbs in blocking SARS-CoV-2 infection.

[Epidemiolological, Clinical, Etiological, Therapeutic And Evolutive Aspects Of Spontaneous Pneumothoraxes In The Internal Medicine Department Of The University Hospital Center Of Abéche (CHU-A) In Chad]. / Aspects Epidemiolologiques, Cliniques, Etiologiques, Therapeutiques Et Evolutifs Des Pneumothorax Spontanes Au Service De Medecine Interne Du Centre Hospitalier Universitaire d'Abéché (CHU-A) Au Tchad.

INTRODUCTION: Pneumothorax are frequent reasons for hospitalization in African pneumological settings. The objective of this work was to describe the epidemiological-clinical, etiological, therapeutic and evolutionary aspects of pneumothorax at the Center Hospitalier Universitaire d'Abéché (CHU-A) in Chad. MATERIALS AND METHODS: This was a prospective and descriptive study conducted in the internal medicine department, from January 1, 2020 to December 31, 2021 concerning cases of pneumothorax. RESULTS: A total of 40 cases of pneumothorax were collected, representing a hospital frequency of 2.38%. The most affected age group was that of 26-45 years (40%) with a male predominance (M/F ratio=2.33). The main contributing factors were smoking (32.5%) and being underweight (55.5%). Acute bacterial pneumonia (57.5%) and tuberculosis (27.5%) were the main etiologies of secondary pneumothorax. Pleural drainage (62.5%), combined with non-specific antibiotic therapy (57.5%) or antituberculous treatment (27.5%) were the main means of management. The evolution was favorable at 90%. We had recorded a hospital mortality of 7.5%. CONCLUSION: Pneumothorax remains frequent in our hospital settings. The dominant etiologies were acute bacterial pneumonia and tuberculosis. The evolution is sometimes interspersed with complications such as residual pneumothorax or pachypleuritis.

BUT: Les pneumothorax sont des motifs fréquents d'hospitalisation en milieux pneumologiques africains. L'objectif de ce travail était de décrire les aspects épidémiologiques, cliniques, étiologiques, thérapeutiques et évolutifs des pneumothorax spontanés au service de médecine interne du Centre Hospitalier Universitaire d'Abéché (CHU-A) au Tchad. MATÉRIEL ET MÉTHODES: Il s'agissait d'une étude prospective et descriptive réalisée dans le service de médecine interne, incluant les patients pris en charge pour pneumothorax spontané, allant du 1er janvier 2020 au 31 décembre 2021. RÉSULTATS: Au total, 40 cas de pneumothorax étaient colligés représentant une fréquence hospitalière de 2,4%. La tranche d'âge la plus touchée était celle de 26-45 ans (40%) avec une prédominance masculine (ratio H/F=2,33). Les principaux facteurs favorisant étaient le tabagisme (32,5%), et l'insuffisance pondérale (55,5%). La pneumopathie aiguë bactérienne (57,5%) et la tuberculose (27,5%) constituaient les principales étiologies du pneumothorax secondaire. Le drainage pleural (62,5%), associé à l'antibiothérapie non spécifique (57,5%) ou au traitement antituberculeux (27,5%) étaient les principaux moyens de prise en charge. L'évolution était favorable à 90%, et la mortalité hospitalière était de 7,5%. CONCLUSION: Le pneumothorax spontané reste une urgence surtout s'il est compressif ou suffocant ou associé à d'autres lésions. Sa prévention repose sur l'éviction des principaux facteurs favorisant qui sont le tabagisme et la dénutrition. Son traitement de référence qui est le drainage pleural impose des politiques sanitaires dans nos pays pour son accessibilité à tous.

[Recrudescence of yellow fever in Chad: case report of the last confirmed case in the health district of Lai-Chad]. / Recrudescence de la fièvre jaune au Tchad: à propos du dernier cas confirmé dans le district sanitaire de Lai-Tchad.

Yellow fever (YF) is a viral haemorrhagic fever caused by yellow fever virus transmitted by Aedes mosquitoes. Since 2013, in Chad, four cases of yellow fever have been detected and confirmed as part of the national fever surveillance program. We here report the last clinical case confirmed in the health district of Lai. The patient was a 57-year-old man with no significant medical and surgical history and unknown immunisation status. He consulted on April 21st, 2020 for fever, moderate to low abundance jaundice and epistaxis (nosebleed) and painful hepatomegaly. Paraclinical examinations, such as RT-PCR, objectified yellow fever virus in post-mortem tissue sample. Thus, confirmed yellow fever cases in this district, the low level of vaccination coverage, the circulation of the virus and the presence of vector in the country should warn of a real threat of reemergence of yellow fever in Chad.