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KHAN, MOHAMMAD ASİF

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MOHAMMAD ASİF
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Item Type: Publication × Author: Khan, Asif M. × Start date: 2020 × End date: 2021 ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Avian Influenza H7N9 Virus Adaptation to Human Hosts
    (2021-05-01T00:00:00Z) Tan, Swan; Sjaugi, Muhammad Farhan; Fong, Siew Chinn; Chong, Li Chuin; Abd Raman, Hadia Syahirah; Nik Mohamed, Nik Elena; August, Joseph Thomas; Khan, Asif M.; KHAN, MOHAMMAD ASİF
    Avian influenza virus A (H7N9), after circulating in avian hosts for decades, was identified as a human pathogen in 2013. Herein, amino acid substitutions possibly essential for human adaptation were identified by comparing the 4706 aligned overlapping nonamer position sequences (1-9, 2-10, etc.) of the reported 2014 and 2017 avian and human H7N9 datasets. The initial set of virus sequences (as of year 2014) exhibited a total of 109 avian-to-human (A2H) signature amino acid substitutions. Each represented the most prevalent substitution at a given avian virus nonamer position that was selectively adapted as the corresponding index (most prevalent sequence) of the human viruses. The majority of these avian substitutions were long-standing in the evolution of H7N9, and only 17 were first detected in 2013 as possibly essential for the initial human adaptation. Strikingly, continued evolution of the avian H7N9 virus has resulted in avian and human protein sequences that are almost identical. This rapid and continued adaptation of the avian H7N9 virus to the human host, with near identity of the avian and human viruses, is associated with increased human infection and a predicted greater risk of human-to-human transmission.
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    PublicationOpen Access
    Dynamics of Influenza A (H5N1) virus protein sequence diversity
    (2020-05-01T00:00:00Z) Abd Raman, Hadia Syahirah; Tan, Swan; August, Joseph Thomas; Khan, Asif M.; KHAN, MOHAMMAD ASİF
    Background. InfluenzaA(H5N1) virus is a global concern with potential as a pandemic threat. High sequence variability of influenza A viruses is a major challenge for effective vaccine design. A continuing goal towards this is a greater understanding of influenza A (H5N1) proteome sequence diversity in the context of the immune system (antigenic diversity), the dynamics of mutation, and effective strategies to overcome the diversity for vaccine design.
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    Absence of BapA type III effector protein affects Burkholderia pseudomallei intracellular lifecycle in human host cells
    (2021-09-01T00:00:00Z) Choh, Leang-Chung; Ong, Guang-Han; Chua, Eng-Guan; Vellasamy, Kumutha Malar; Mariappan, Vanitha; Khan, Asif M.; Wise, Micheal J.; Wong, Kum-Thong; Vadivelu, Jamuna; KHAN, MOHAMMAD ASİF
    The etiological agent of melioidosis, Burkholderia pseudomallei, utilises a type III secretion system cluster 3 (T3SS3) to deliver proteins termed type III effectors (T3SEs) into the host cytoplasm in order to establish an intracellular lifecycle in phagocytic and non-phagocytic cells, thus playing an important role in pathogenesis. To gain insight into possible functional roles for BapA, a putative T3SE with unknown function, in the intracellular lifecycle of B.pseudomallei, bapA gene knockout mutant was constructed. The effect of the knockout on virulence to the otherwise isogenic parental strain, K96243, was studied by cellular infection assays and Caenorhabditis elegans killing assay. The attachment and subsequent entry into A549 cells was significantly (P < 0.05) attenuated in the Delta bapA compared to K96243. However, intracellular replication was not affected. Furthermore, the cell-to-cell spreading capacity of Delta bapA was impaired although the mutant exhibited no evident defect in its actin tail formation. Additionally, phagocytosis and intracellular replication rates of Delta bapA in U937 macrophage cells were significantly reduced relative to K96243 without phagosomal escape being affected. Based on these observations, we conclude that the BapA T3SE could play an important role in B.pseudomallei intracellular lifecycle, especially, in the early stages of attachment and entry into the host cell.