مسح ودراسة النماط الجزينية لفيروس الانفلونزا A بين الفلسطينيين
Survey and Molecular Typing of Influenza A Virus among Palestinians
ميسون صادق ياسين البكري
maysoon sadek yaseen Al Bakri
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Influenza A virus (IAV) causes significant mortality, morbidity, and financial burden throughout the world. IAV is a negative, single-stranded, and segmented RNA virus of the Orthomyxoviridae family. IAV subtypes are determined based on its two surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA). H1N1 and H3N2 are the major circulating subtypes among humans. Frequent genotyping of IAV strains throughout the influenza season is crucial for the identification of circulating subtypes and subsequently the choice of the H3N2 and H1N1 subtypes’ lineages to be included in the annually prepared vaccine cocktail. Sequencing and identification of circulating subtypes in the region continues to be less frequent and less intensive than in other parts of the world, despite increasing interest and efforts made ever since the swine H1N1 outbreak in 2009. This work presents the first comprehensive study on IAV circulating in Palestine. 200 Nasopharyngeal aspirate (NPA) samples were collected between February 10th and May 5th, 2015 from participants suffering from mild to severe symptoms of upper respiratory infections and were screened for the presence of IAV using RT-PCR assays amplifying the HA and NA gene regions. 50 samples (25%) tested positive for IAV, 24 (48%) were identified as H1N1, and 26 (52%) were identified as H3N2 subtype, respectively. Infection with H1N1 occurred mainly in April, while H3N2 infections were mainly detected in March. Most IAV infections in children younger than 6-year-old were attributed to subtypes H3N2, while H1N1 was responsible for most infections in adults older than eighteen-year-old. Hundred-fifteen sequences of the HA and NA genes were successfully analyzed. These sequences belong to 23 IAV positive Palestinian IAV samples. The percent identity of thesequences among Palestinian isolates was higher than that between Palestinian isolates and GenBank-archived reference sequences. 14, 15, 22 and 6 non-synonymous substitutions were detected in the Palestinian H1, N1, H3 and N2 genes, including novel ones, respectively. Some of these amino acid substitutions localized to the antigenic sites, T202S and Q180K in H1 gene, T144A and L173S in H3 gene. Such substitutions in the antigenic sites may affect the hostimmune response. Other substitutions located at the receptor binding sites, such as T228A in H3 gene, may affect viral binding activity to host cell receptor, and subsequently its virulence and host species barrier.None of the substitutions detected in this work were associated with drug resistance or fatal outcomes. Phylogenetic analysis revealed that Palestinian H1N1 and H3N2 were not closely related to those regionally circulating strains and clustered closer to international, rather nonregional strains. The results of this study are significant in providing the first insight into the genetic properties of the HA and NA genes of the influenza A viruses circulating in Palestine. Finally, this study provides evidence of the efficacy of the seasonal influenza vaccine 2014-2015 in Palestine.