Staphylococcus aureus Lipase 1 Enhances Influenza A Virus Replication

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p>Influenza A virus (IAV) causes annual epidemics of respiratory disease in humans, often complicated by secondary coinfection with bacterial pathogens such as <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content>. Here, we report that the <jats:named-content content-type="genus-species">S. aureus</jats:named-content> secreted protein lipase 1 enhances IAV replication <jats:italic>in vitro</jats:italic> in primary cells, including human lung fibroblasts. The proviral activity of lipase 1 is dependent on its enzymatic function, acts late in the viral life cycle, and results in increased infectivity through positive modulation of virus budding. Furthermore, the proviral effect of lipase 1 on IAV is exhibited during <jats:italic>in vivo</jats:italic> infection of embryonated hen’s eggs and, importantly, increases the yield of a vaccine strain of IAV by approximately 5-fold. Thus, we have identified the first <jats:named-content content-type="genus-species">S. aureus</jats:named-content> protein to enhance IAV replication, suggesting a potential role in coinfection. Importantly, this activity may be harnessed to address global shortages of influenza vaccines.</jats:p> <jats:p><jats:bold>IMPORTANCE</jats:bold> Influenza A virus (IAV) causes annual epidemics and sporadic pandemics of respiratory disease. Secondary bacterial coinfection by organisms such as <jats:named-content content-type="genus-species">Staphylococcus aureus</jats:named-content> is the most common complication of primary IAV infection and is associated with high levels of morbidity and mortality. Here, we report the first identified <jats:named-content content-type="genus-species">S. aureus</jats:named-content> factor (lipase 1) that enhances IAV replication during infection via positive modulation of virus budding. The effect is observed <jats:italic>in vivo</jats:italic> in embryonated hen’s eggs and greatly enhances the yield of a vaccine strain, a finding that could be applied to address global shortages of influenza vaccines.</jats:p>

Staphylococcus aureus Bacteremia in Patients Infected With COVID-19: A Case Series

“…S. aureus infections are a known complication of other viral pandemics, such as the Spanish flu in 1918–1919 and the H1N1 influenza pandemic in 2009–2010 [ 8 , 20 ]. S. aureus is known to act synergistically in all influenza seasons, increasing mortality and severity of disease [ 7 , 21 , 22 ]. The proposed mechanisms of viral-induced bacterial co-infections include viral modification of airway structures, as well as initiation of immune-suppressive responses [ 23–25 ].…”

Staphylococcus aureus secreted lipases do not inhibit innate immune killing mechanisms

“…40% (v/v) glycerol stocks of both a wild type ( S. aureus USA300 WT) and an isogenic mutant ( S. aureus USA300 Δlip1/Δlip2) of the CC8 epidemic clone S. aureus USA300 LAC generated in a previous study 19 were stored at -80°C. When required, stocks were sub-cultured onto tryptone soy agar (TSA, Oxoid CM131B) or cultured into tryptone soy broth (TSB, Oxoid CM129B) overnight at 37°C with agitation (200 rpm).…”

“…Expression plasmid constructs pET156:: lip1 or pET156:: lip2 19 were transformed into ClearColi ® BL21 (DE3) electrocompetent cells (Lucigen, 60810-1) by electroporation, according to the manufacturer’s instructions. Cells were grown in LB Miller broth (Sigma, L3522-250G) to an OD 600 of 0.6 and protein expression was induced with 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG, Formedium Ltd, IPTG025) for 4 h at 37°C, with agitation (200 rpm), before centrifugation and storage at -20°C.…”

“…Hexa-histidine tagged proteins were purified by immobilised metal affinity chromatography as described previously 19 . Western blot analysis confirmed the presence of hexa-histidine tagged proteins at 76 kDa (1 in 10,000 monoclonal anti-poly His, α-diagnostics HISP12-HRP, in 8% (w/v) skimmed milk (Sigma, 70166-500G) in sterile phosphate buffered saline (PBS)).…”

Staphylococcus aureus secreted lipases do not inhibit innate immune killing mechanisms

“…Purification of recombinant lipase1 (rLip1) and 2 (rLip2) Expression plasmid constructs pET156::lip1 or pET156::lip2 20 were transformed into ClearColi ® BL21 (DE3) electrocompetent cells (Lucigen, 60810-1) by electroporation, according to the manufacturer's instructions. Cells were grown in LB Miller broth (Sigma, L3522-250G) to an OD 600 of 0.6 and protein expression was induced with 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG, Formedium Ltd, IPTG025) for 4 h at 37°C, with agitation (200 rpm), before centrifugation and storage at -20°C.…”