Investment in SARS-CoV-2 sequencing in Africa over the past year has led to a major increase in the number of sequences generated, now exceeding 100,000 genomes, used to track the pandemic on the continent. Our results show an increase in the number of African countries able to sequence domestically, and highlight that local sequencing enables faster turnaround time and more regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and shed light on the distinct dispersal dynamics of Variants of Concern, particularly Alpha, Beta, Delta, and Omicron, on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve, while the continent faces many emerging and re-emerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century.

Many studies suggest that the focal distribution of nasopharyngeal carcinoma (NPC) may be influenced not only by host genetics, diet and environments but also by interplay with Epstein-Barr virus (EBV) genetics. Specific EBV gene variants (the A and C types, the BamHI f configuration, a C terminal 30 bp deletion and a N terminal loss of an XhoI site in the BNLF1 gene) have been explored in high incidence areas in southern Asian NPC patients. In contrast, in Tunisia where NPC represents the most frequent type of Head and Neck cancer the distribution of these polymorphisms remains poorly investigated. In order to characterize the epidemiology of EBV variants in Tunisian NPC patients, we have investigated the A or B type of the EBV nuclear antigen (EBNA)2 gene, the C or D type of the BamHI W1/I1 region, the F/f variants of the BamHI F region and the presence or the absence of the XhoI site, 30 bp deletion and Taq1 site in the BNLF1 gene in 47 NPC biopsies, 12 being younger than 30 and 35 older than 30. Our results show a unique genetic profile of the tumor EBV strains regarding the A and D types, the prototype F and retention of the XhoI restriction site in the N terminal region of BNLF1 gene. With regard to the C terminal region of this gene, four genetic profiles were detected: (1) the occurrence of the 30 bp deletion in association with the Taq1 site in 39 cases (83%), (2) the presence of the Taq1 site by itself in 5 cases, (3) the occurrence of the 30 bp deletion by itself in 2 cases and (4) the occurrence of a new deletion of 81 bp covering the 30 bp deletion in association with the Taq1 site in one case. With the exception of the 81 bp deletion, which has not been previously described in the literature, the summarized results have shown the same genetic profile in Tunisian NPC tumor isolates as tumor isolates from other North African and Mediterranean countries. Hence, the observed EBV polymorphisms are not fully specific of to the Tunisian NPCs. Nevertheless, the notion of a divergence between North African and Asian tumor EBV isolates is reinforced by this study.

No abstract

No abstract

Objectives Since the onset of the COVID-19 pandemic, cases of reinfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported, raising additional public health concerns. SARS-CoV-2 reinfection was assessed in healthcare workers in Tunisia, as they are at the greatest exposure to infection by different variants. Methods We conducted whole-genome sequencing of the viral RNA from clinical specimens at the initial infection and suspected second infection from four healthcare workers, working at the Habib Bourguiba University Hospital (Sfax, Tunisia), who were retested positive for SARS-CoV-2 by RT-PCR after recovery from a first infection. A total of 8 viral RNAs from the patients’ respiratory specimens were obtained, which allowed us to characterize the differences between viral genomes from initial infection and positive retest. The serology status for total Ig, IgG, and IgM against SARS-CoV-2 was also determined and followed after the first infection. Results We confirmed by whole-genome sequencing of the viral samples that all four cases experienced a reinfection event. The interval between the two infection events ranged from 45 to 141 days and symptoms were milder in the second infection for two patients and more severe for the two remaining cases. Reinfection occurred for all four cases, despite the presence of antibodies for three of them. Conclusion This study adds to the rapidly growing evidence of COVID-19 reinfection, where viral sequences were used to confirm infection by distinct isolates of SARS-CoV-2 in healthcare workers. These findings suggest that individuals, who are exposed to different SARS-CoV-2 variants, might not acquire sufficiently protective immunity through natural infection and emphasis the necessity of their vaccination and the regular follow-up of their immune status both in quantitative and qualitative terms.