The Correlation of IFN &amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt; to the Preferential Isolation of Influenza Type B over Type A Viruses in Madin Darby Canine Kidney Cells

Timothy Byaruhanga,Barbara Namagambo,Nicholas Owor,Barnabas Bakamuntumaho,Joyce Namulondo,Julius Julian Lutwama,John Timothy Kayiwa,Bernard Bagaya,Irene Nabukenya

doi:10.4236/ojmm.2017.71002

Abstract

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.

Highlights

This study investigated the differences in IFN-γ and Interleukin 10 (IL-10) cytokines secreted by Madin Darby Canine Kidney (MDCK) cells upon exposure to the viruses and provided possible answers as to why influenza type B can be isolated from MDCK cells compared to influenza A
There are 18 HA and 11 NA which can undergo re-assortment or mutations to give rise to new or variant strain among influenza type A viruses. It was in this regard that strains such as the case of influenza B had formed a homogeneous group, which started to diverge antigenically into two distinct lineages, whose first representatives were B/Victoria/2/87 and B/Yamagata/16/88, as the Victoria and Yamagata lineages respectively [3]
Sample size The hypothesis comparing the means of the outcome variable in the two independent populations was considered

Summary

Introduction

There are 18 HA and 11 NA which can undergo re-assortment or mutations to give rise to new or variant strain among influenza type A viruses It was in this regard that strains such as the case of influenza B had formed a homogeneous group, which started to diverge antigenically into two distinct lineages, whose first representatives were B/Victoria/2/87 and B/Yamagata/16/88, as the Victoria and Yamagata lineages respectively [3]. This nomenclature system was adapted after the World Health Organization (WHO) where B denotes for the type of Influenza virus, Victoria as the place of origin, 2 as the strain serial number and 87 as the year of isolation. A similar nomenclature system exists for influenza A viruses [4]

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Results

Conclusion