Jayme Herbert, University of the Free State/Deltamune

J. Herbert - University of the Free State, Bloemfontein South Africa and Deltamune (PTY) LTD, Pretoria South Africa P. le Roux - North-West University, Potchefstroom South Africa C.M. Cooke - North-West University, Potchefstroom South Africa A.C. Potgieter - North-West University, Potchefstroom South Africa and Deltamune (PTY) LTD, Pretoria South Africa H.G. O' Neill - University of the Free State, Bloemfontein South Africa L. Zandberg - North-West University, Potchefstroom South Africa A.A. van Dijk - University of the Free State, Bloemfontein South Africa

Cell Biology of Viral Infection

Rotaviruses are segmented dsRNA viruses and cause dehydrating gastroenteritis in children younger than five years. Rotavirus NSP6 is an 11-kDa nucleic acid-binding non-structural protein and has been shown to localise to the outer mitochondrial membrane. However, the effect of NSP6 on the mitochondria is unknown. To investigate whether NSP6 affects mitochondrial membrane dynamics, rSA11, rSA11 with a NSP6 knockout (rSA11-ΔNSP6), and uninfected MA104 mitochondrial-enriched fractions were extracted, and phospholipid fatty acids were analysed using GC-MS. Analysis of type and chain lengths of phospholipid fatty acids showed that infection with rSA11 resulted in a higher representation of saturated fatty acids in the mitochondria when compared to rSA11-ΔNSP6 and uninfected MA104. Conversely, infection with rSA11-ΔNSP6 resulted in higher composition of long-chain fatty acids than very long-chain fatty acids when compared to rSA11 and uninfected MA104. Statistical analysis (Mann-Whitney and fold change) showed for rSA11-ΔNSP6 vs rSA11, nervonic acid (C24_1n9) and oleic acid (C18_1n9), represented a significantly increased composition, resulting in more fluid membranes. For rSA11 vs MA104, arachidonic acid (C20_4n6), gondoic acid (C20_1n9), and nervonic acid (C24_1n9) were significantly less represented, whereas palmitic acid (C16) had a higher percentage composition, resulting in increased membrane rigidity. Finally, for rSA11-ΔNSP6 vs MA104, myristic acid (C14) had a higher composition. This shows that NSP6 may mediate more viscous mitochondrial membranes by driving the substitution of unsaturated for saturated fatty acids in membrane phospholipids. An additional viral mediator must be considered.