We used influenza C sequences available in the GISAID EpiFlu database (https://www.gisaid.org) as of April 18, 2018, to design primers for whole-genome sequencing by next-generation sequencing and Sanger sequencing of the hemagglutinin-esterase (HE) gene.
Hemagglutinin-esterase gene phylogeny for influenza C viruses detected in Cameroon compared with reference viruses.
CoVs are enveloped, single-stranded positive sense RNA viruses with a genome encoding replicase polyproteins, the four structural proteins: spike (S) glycoprotein (a receptor-interacting and a target for neutralizing antibody in the envelope); nucleocapsid (N) (associated with the genomic RNA in the nucleocapsid); and the two proteins essential for virion formation, envelope (E) and membrane (M) proteins; some Betacoronaviruses also present the hemagglutinin-esterase
(HE) protein, with the role as a secondary receptor-binding envelope protein and accessory proteins [3, 4].
In addition, the splicing pattern of the matrix gene segment and the reduced 5-N-acetyl binding pocket in the hemagglutinin-esterase
(HE) protein of D/bovine/France/2986/2012 was similar to that of C/OK and different from that of human influenza C virus, confirming the similarity of D/ bovine/France/2956/2012 and the newly described swine and bovine US influenza D virus strains.
At this stage, it is speculative if this could be due to the lack of the hemagglutinin-esterase
protein (8,35) in the spike glycoprotein of this virus.