Browsing by Author "Kayiwa, John Timothy"

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    Genetic Diversity of Bundibugyo Ebolavirus from Uganda and the Democratic Republic of Congo
    (bioRxiv, 2021) Omara, Isaac Emmanuel; Kiwuwa-Muyingo, Sylvia; Balinandi, Stephen; Nyakarahuka, Luke; Kiconco, Jocelyn; Kayiwa, John Timothy; Mboowa, Gerald; Jjingo, Daudi; Lutwama, Julius J.
    The Ebolavirus is one of the deadliest viral pathogens which was first discovered in the year 1976 during two consecutive outbreaks in the Democratic Republic of Congo and Sudan. Six known strains have been documented. The Bundibugyo Ebolavirus in particular first emerged in the year 2007 in Uganda. This outbreak was constituted with 116 human cases and 39 laboratory confirmed deaths. After 5 years, it re-emerged and caused an epidemic for the first time in the Democratic Republic of Congo in the year 2012 as reported by the WHO. Here, 36 human cases with 13 laboratory confirmed deaths were registered. Despite several research studies conducted in the past, there is still scarcity of knowledge available on the genetic diversity of Bundibugyo Ebolavirus. We undertook a research project to provide insights into the unique variants of Bundibugyo Ebolavirus that circulated in the two epidemics that occurred in Uganda and the Democratic Republic of Congo
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    Phylogenomic analysis of Uganda influenza type-A viruses to assess their relatedness to the vaccine strains and other Africa viruses: a molecular epidemiology study
    (bioRxiv, 2021) Nabakooza, Grace; Owuor, David Collins; Laurent, Zaydah R. de; Owor, Nicholas; Kayiwa, John Timothy; Jjingo, Daudi; Nyaigoti Agoti, Charles; Nokes, David James; Kateete, David Patrick; Mulindwa Kitayimbwa, John; Frost, Simon David William; Lutwama, Julius Julian
    Genetic characterisation of circulating influenza viruses is essential for vaccine selection and mitigation of viral transmission. The current scantiness of viral genomic data and underutilisation of advanced molecular analysis methods on influenza viruses circulating in Africa has limited their extensive study and representation in the global influenza ecology. We aimed to sequence influenza type-A viruses (IAVs) that previously circulated in Uganda and characterised their genetic relatedness to the vaccine viruses and publicly available Africa IAVs. Methods: This was an observational study nested to the Uganda national influenza surveillance programme. We used Next-generation sequencing to locally generate genomes from 116 A(H1N1)pdm09 and 118 A(H3N2) viruses collected between 2010 and 2018 from 7 districts across Uganda. A total of 206 hemagglutinin (HA), 207 neuraminidase (NA), and 213 matrix protein (MP) sequences were genetically compared to the WHO-recommended vaccines and other viruses isolated from Africa since 1994. Viral temporal and spatial divergence and circulating genetic clades were characterised using phylogenetic methods. Findings: We successfully generated gene sequences for 91·9% (215/234) viruses. Uganda A(H1N1)pdm09 and A(H3N2) virus HA, NA, and MP proteins had 96·36-99·09%, 96·49-99·39%, and 97·48-99·95% amino acid similarity, respectively, to vaccines recommended from 2010 through 2020. The local viruses incorporated amino acid substitutions (AAS) in their antigenic, receptor binding, and glycosylation sites each year causing them to antigenically drift away from vaccines. For seasons when vaccine formulations differed, Uganda IAV antigenic sites had 1-2 extra AAS relative to the Southern than Northern hemisphere vaccine viruses. All Uganda IAVs carried the adamantine-resistance marker S31N but not the neuraminidase inhibitor (NAI) resistance markers H274Y and H275Y. However, some A(H1N1)pdm09 viruses had permissive substitutions V234I, N369K, and V241I typical of NAI-resistant viruses.
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    The Correlation of IFN γ to the Preferential Isolation of Influenza Type B over Type A Viruses in Madin Darby Canine Kidney Cells
    (Open Journal of Medical Microbiology, 2017) Byaruhanga, Timothy; Bagaya, Bernard; Namulondo, Joyce; Kayiwa, John Timothy; Namagambo, Barbara; Owor, Nicholas; Nabukenya, Irene; Bakamuntumaho, Barnabas; Lutwama, Julius Julian
    The isolation of influenza viruses in Madin Darby Canine Kidney (MDCK) cells has shown preferential isolation of a great percentage of Influenza B strains at the first passage than Influenza A strains. During in vitro isolation of Influenza viruses, majority of type A viruses are not confirmed as positive isolates by Hemagglutination (HA) assay despite having higher virulence and pathogenicity versus influenza B viruses. This study investigated the differences in IFN-γ and IL-10 cytokines secreted by MDCK cells upon exposure to the viruses and thus provided possible answers as to why influenza type B can easily be isolated from MDCK cells compared to influenza A. Positive influenza viruses were inoculated onto MDCK cells. IFN-γ and IL-10 cytokines stimulated by the viruses in MDCK cells were measured by indirect ELISA at 1 hour, 12 hours, 48 hours and 72 hours post inoculation (pi). A total of 46 specimens, with 23 specimens from each virus type were analyzed. IFN-γ was significantly higher at 1 hour pi in MDCK cells for influenza type A at p value of 0.024 than type B. No statistical significance was observed in means of cytokine IL-10 between influenza type A and type B. The study may show that IFN-γ is correlated to the preferential isolation of influenza type B over type A viruses. Anti-inflammatory cytokines may not necessarily be playing a role in the preferential growth of influenza type B, a less virulent type over influenza type A in MDCK cells.