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Background COVID-19, the coronavirus disease that emerged in December 2019, caused drastic damage worldwide. At the beginning of the pandemic, available data suggested that the infection occurs more frequently in adults than in infants. In this review, we aim to provide an overview of SARS-CoV-2 infection in children before and after B.1.617.2 Delta and B.1.1.529 Omicron variants emergence in terms of prevalence, transmission dynamics, clinical manifestations, complications and risk factors. Methods Our method is based on the literature search on PubMed, Science Direct and Google Scholar. From January 2020 to July 2022, a total of 229 references, relevant for the purpose of this review, were considered. Results The incidence of SARS-CoV-2 infection in infants was underestimated. Up to the first half of May, most of the infected children presented asymptomatic or mild manifestations. The prevalence of COVID-19 varied from country to another: the highest was reported in the United States (22.5%). COVID-19 can progress and become more severe, especially with the presence of underlying health conditions. It can also progress into Kawasaki or Multisystem Inflammatory Syndrome (MIS) manifestations, as a consequence of exacerbating immune response. With the emergence of the B.1.617.2 Delta and B.1.1.529 Omicron variants, it seems that these variants affect a large proportion of the younger population with the appearance of clinical manifestations similar to those presented by adults with important hospitalization rates. Conclusion The pediatric population constitutes a vulnerable group that requires particular attention, especially with the emergence of more virulent variants. The increase of symptomatic SARS-CoV-2 infection and hospitalization rate among children highlights the need to extend vaccination to the pediatric population.

The SARS-CoV-2 Omicron variant has exhibited a rapid progression around the world, but its molecular insights in North Africa remain understudied. This study characterizes the genetic diversity, dynamics, and evolutionary trends of the Omicron variant in Tunisia over a 33-month period (December 2021–August 2024). In total, 928 high-quality whole-genome sequences were considered in this study, of which 559 were retrieved from the GISAID database and 369 were generated in our laboratory. Phylogenetic analysis of the dominant subvariants (BA.1, BA.2, and BA.5) was performed using IQ-TREE. BA.2 was the predominant subvariant (38%), followed by BA.1 (24.0%), Omicron recombinants (19%), and BA.5 (18%). BA.2 diversified into JN, KP, and BN sub-lineages. Recombinants were dominated by XBB (98.8%), primarily including EG.4, XBB.1.5, and XBB.2.3.11, with rare detection of XDK and XDQ. Phylogenetic analysis revealed local clusters in BA.1, BA.2, and BA.5 alongside imported strains. Tunisia’s Omicron wave was mainly driven by BA.2 and its recombinants, with evidence of localized viral evolution and sporadic introductions. The detection of rare recombinants underlines the importance of integrating regional genomic surveillance with epidemiological data in order to help guide future public health strategies.

Background Coronavirus Disease 2019 (COVID-19) is a viral pandemic disease that may induce severe pneumonia in humans. In this paper, we investigated the putative implication of 12 vaccines, including BCG, OPV and MMR in the protection against COVID-19. Sequences of the main antigenic proteins in the investigated vaccines and SARS-CoV-2 proteins were compared to identify similar patterns. The immunogenic effect of identified segments was, then, assessed using a combination of structural and antigenicity prediction tools. Results A total of 14 highly similar segments were identified in the investigated vaccines. Structural and antigenicity prediction analysis showed that, among the identified patterns, three segments in Hepatitis B, Tetanus, and Measles proteins presented antigenic properties that can induce putative protective effect against COVID-19. Conclusions Our results suggest a possible protective effect of HBV, Tetanus and Measles vaccines against COVID-19, which may explain the variation of the disease severity among regions.

Background The COVID-19 has put emphasis on pivotal needs for diagnosis and surveillance worldwide, with the subsequent shortage of diagnostic reagents and kits. Therefore, it has become strategic for the countries to access diagnostics, expand testing capacity, and develop their own diagnostic capabilities and alternative rapid accurate nucleic acid diagnostics that are at lower costs. Here, we propose a visual SARS-CoV-2 detection using a one-step fast multiplex reverse transcription-PCR (RT-PCR) amplification coupled to lateral flow immunoassay detection on a PCRD device (Abingdon Health, UK). Methods We developed various simplex fast-PCRs for screening sets of primer pairs newly designed or selected from literature or from validated WHO diagnostics, targeting S , N , E , RdRp or ORF1ab genes. We retained primers showing specific and stable amplification to assess for their suitability for detection on PCRD. Thus, fast RT-PCR amplifications were performed using the retained primers. They were doubly labeled with Fam and Biotin or Dig and Biotin to allow visual detection of the labeled amplicons on the lateral flow immunoassay PCR D etection (PCRD) device, looking at lack of interaction of the labeled primers (or primer dimers) with the test-lines in negative or no RNA controls. We set up all the assays using RNAs isolated from patients’ nasopharyngeal swabs. We used two simplex assays, targeting two different viral genomic regions ( N and E ) and showing specific detection on PCRD, to set up a one-step fast multiplex RT-PCR assay (where both differently labeled primer pairs were engaged) coupled to amplicons’ detection on a PCRD device. We evaluated this novel assay on 50 SARS-CoV-2 positive and 50 SARS-CoV-2 negative samples and compared its performance to the results of the quantitative RT-PCR (RT-qPCR) assays used for diagnosing the patients, here considered as the standard tests. Results The new assay achieved a sensitivity of 88% (44/50) and a specificity of 98% (49/50). All patients who presented Ct values lower than 33 were positive for our assay. Except for one patient, those with Ct values above 33 returned negative results. Conclusion Our results have brought proof of principle on the usefulness of the one-step fast multiplex RT- PCR assay coupled to PCRD as a new assay for specific, sensitive, and rapid detection of SARS-CoV-2 without requiring costly laboratory equipment, and thus, at reduced costs in a format prone to be deployed when resources are limited. This assay offers a viable alternative for COVID-19 diagnosis or screening at points of need.

Background The intra-host diversity of SARS-CoV-2 in pediatric populations remains insufficiently studied. To address this significant knowledge gap, the present study investigates the intra-host variability of SARS-CoV-2 in both immunocompetent and immunodeficient children, including those with severe cases. The research encompasses both short-term and long-term infections, aiming to provide a comprehensive understanding of viral dynamics in these vulnerable groups. Materials and methods This study analyzed 47 pediatric COVID-19 patients: 37 with short-term infections and 10 with long-term infections including 3 immunodeficient cases. Viral RNA was extracted and detected using RT-qPCR, followed by whole-genome sequencing (WGS) using the Illumina COVIDSeq assay. Bioinformatics analysis was performed with the nextflow/viralrecon pipeline. The number of single nucleotide polymorphisms (SNPs) and the frequency of Major (M-SNPs) and minor (m-SNPs) missense SNPs were analyzed using the ggplot2 R package and GraphPad Prism software, respectively. Results A total of 96 SARS-CoV-2 sequences from 45 patients (35 short-term and 10 long-term shedders), were classified into four variants: Alpha, B.1.160, Delta, and Omicron. SNPs were common across SARS-CoV-2 variants (88.21%-100%), with frequent cytosine-to-thymidine (C > T) substitutions (44.05%-52.85%). Missense mutations were also prominent (57.52% to 80.32%). Variability in SNPs numbers was observed over time in Delta and Omicron variants, particularly in severe and immunodeficient cases. Missense m-SNPs exhibited variation in long-term shedders, especially among severe immunocompetent and immunodeficient patients. Conclusion Our findings revealed significant intra-host variability in SARS-CoV-2 among severe and immunodeficient pediatric patients. These results underscore the critical importance of continuous surveillance of viral variants within pediatric populations to enhance our understanding of their impact on disease progression and clinical outcomes.

Introduction RT-PCR testing on nasopharyngeal swabs is a key component in the COVID-19 fighting, provided to use sensitive and specific SARS-CoV2 genome targets. In this study, we aimed to evaluate and to compare 4 widely used WHO approved RT-PCR protocols on real clinical specimens, to decrypt the reasons of the diverging results and to propose recommendations for the choice of the genome targets. Methods 260 nasopharyngeal samples were randomly selected among the samples tested between Week-16, 2020 and week-16 2021, in the Institut Pasteur de Tunis, Tunisia, one of the referent laboratories of COVID-19 in Tunisia. All samples were tested by Charité, Berlin protocol (singleplex envelop (E) and singleplex RNA-dependent RNA polymerase (RdRp)), Hong Kong Universiy, China protocol (singleplex nucleoprotein (N) and singleplex Open reading frame Orf1b), commercial test DAAN Gene® (using the CDC China protocol), (triplex N, Orf1ab with internal control) and Institut Pasteur Paris protocol (IPP) (triplex IP2(nsp9) and IP4 (nsp12) with internal control). For IPP, a selection from samples positive by IP2 but negative with IP4 was re-tested by exactly the same protocol but this time in singleplex. New results were described and analyzed. Results In vitro analysis showed discordant results in 29.2% of cases (76 out of 260). The most discordant protocol is DAAN Gene® due to the false positive late signals with N target. Discordant results between the two protocol’s targets are more frequent when viral load are low (high Ct values). Our results demonstrated that the multiplexing has worsened the sensitivity of the IP4 target. Conclusion We provide concise recommendations for the choice of the genome targets, the interpretation of the results and the alarm signals which makes suspect a gene mutation.

Hepatitis C virus (HCV) has a high genetic diversity. Eight genotypes and 90 subtypes are currently described. Genotypes are clinically significant for therapeutic management and their determination is necessary for epidemiological studies. Tunisian patients plasma samples (n = 6) with unassigned HCV-2 subtype using partial sequencing in the NS5B and Core/E1 regions were analyzed by realizing whole-genome sequencing analysis. Phylogenetic analyses were performed to assign subtypes. Phylogenetic analysis of the full genome sequences of Tunisian strains shows two subtypes within HCV-2. These later were genetically distinct from all previously established HCV-2 subtypes with nucleotide divergence greater than 15% (20% -31%). These two subtypes are proposed as new subtypes 2v and 2w. The discovery of two new HCV-2 subtypes circulating in the Tunisian population confirms the great diversity of HCV-2 viruses and increases the total number of HCV-2 subtypes from 21 to 23.

Following the emergence of SARS-CoV-2, it became prominent that the genetic background of the patient influences the disease prognosis and treatment. [...]multiple genetic databases were established to study precision medicine for COVID-19 (2). [...]the study reported a positive correlation between ACE1 I and the risk of acquiring COVID-19 as well as between the ACE1-D allele and its negative impact following SARS-CoV-2 infection. [...]the authors suggested that genotyping for ACE1 I/D polymorphism could be useful for better management of the disease. [...]the delay in identifying the etiological agents and corresponding treatment in patients with CNS infections leads to worse management and outcomes.Chen et al.reported a case study on herpes simplex encephalitis (HSE). [...]personalized or precision medicine is a growing approach to improve patient care by applying the right intervention at the right time. According to the GWAS Catalog statistics (OCT 2020), out of 4,761 publications, only eighty-six were related to infectious diseases (ID) (1.8%).

Documenting the circulation dynamics of SARS-CoV-2 variants in different regions of the world is crucial for monitoring virus transmission worldwide and contributing to global efforts towards combating the pandemic. Tunisia has experienced several waves of COVID-19 with a significant number of infections and deaths. The present study provides genetic information on the different lineages of SARS-CoV-2 that circulated in Tunisia over 17 months. Lineages were assigned for 1359 samples using whole-genome sequencing, partial S gene sequencing and variant-specific real-time RT-PCR tests. Forty-eight different lineages of SARS-CoV-2 were identified, including variants of concern (VOCs), variants of interest (VOIs) and variants under monitoring (VUMs), particularly Alpha, Beta, Delta, A.27, Zeta and Eta. The first wave, limited to imported and import-related cases, was characterized by a small number of positive samples and lineages. During the second wave, a large number of lineages were detected; the third wave was marked by the predominance of the Alpha VOC, and the fourth wave was characterized by the predominance of the Delta VOC. This study adds new genomic data to the global context of COVID-19, particularly from the North African region, and highlights the importance of the timely molecular characterization of circulating strains.

Rhinoviruses (RV) are a major cause of Severe Acute Respiratory Infection (SARI) in children, with high genotypic diversity in different regions. However, RV type diversity remains unknown in several regions of the world. In this study, the genetic variability of the frequently circulating RV types in Northern Tunisia was investigated, using phylogenetic and phylogeographic analyses with a specific focus on the most frequent RV types: RV-A101 and RV-C45. This study concerned 13 RV types frequently circulating in Northern Tunisia. They were obtained from respiratory samples collected in 271 pediatric SARI cases, between September 2015 and November 2017. A total of 37 RV VP4-VP2 sequences, selected among a total of 49 generated sequences, was compared to 359 sequences from different regions of the world. Evolutionary analysis of RV-A101 and RV-C45 showed high genetic relationship between different Tunisian strains and Malaysian strains. RV-A101 and C45 progenitor viruses’ dates were estimated in 1981 and 1995, respectively. Since the early 2000s, the two types had a wide spread throughout the world. Phylogenetic analyses of other frequently circulating strains showed significant homology of Tunisian strains from the same epidemic period, in contrast with earlier strains. The genetic relatedness of RV-A101 and RV-C45 might result from an introduction of viruses from different clades followed by local dissemination rather than a local persistence of an endemic clades along seasons. International traffic may play a key role in the spread of RV-A101, RV-C45, and other RVs.