THE STRANGE ONE: Haemagglutinin-esterase
in Influenza C
Influenza C is
a genus from the family Orthomixoviridae, it’s the unique genus of this family
that express haemagglutinin-esterase, and as is a viruses that causes illness
in humans we decided studied it more.
Using a specific database from flu, which is the illnesses that is caused by Influenza, we found
more sequences from different years and places. We select 13 sequences based in the
periodicity of years, the 13 sequences that we choose are from consecutive
years and for the years that we found more than one sequence we choose a couple
of them (the sequences more similar between them).
We analyze the protein sequence, we compared it with
P-fam and with Prodom doing the same that we do from analyzes of different organism.
After, we analyze the multiple domains that we found in Prodom with Prosite, as
we do with the random organism.
With P-fam, we found a difference between these sequences and Coronavirus’
sequences. In its C-terminal end has a long tail that doesn’t exist in the
other family of viruses that express haemagglutinin-esterase. This tail
contains a coiled coil and a transmembrane domain. The coiled coil usually is
used to control oligomerisation, so in this case, haemagglutinin-esterase isn’t
a monomer structure, it is a dimmer or trymmeric structure. In its N-terminal
end it usually doesn’t have the signal sequence.
With Prodom we found a signal peptide in some sequences, the
precursor signal envelope hydrolase, and the sequence of one of this chains
(chain 4), that is specific of Influenza C’s haemagglutinin-esterase.
We analyze the protein with Blocks and we found an initial region very conserved that we hadn’t find before, part of this region is the same phosphorilation site that we found in the analysis of the family sequences in Blocks database. Its function we didn’t know but maybe, it’s related with its third structure. If this motif were an external region, it can be a good target for a vaccine.
We aligned the sequences with ClustalW and we made the phylogenetic analysis. We realize the Neighbor-joining and Maximum-parsimony consens tree with Phylip, using bootstrap with thousand possible alignations. We analyze the phylogeny with a Maximum-likelihood tree too, in this case, without bootstrap and with Tree-puzzle 5.0 program.
We analyze the similarity of haemagglutinin-esterase
in Influenza C with the haemagglutinin in Influenza A and Influenza B to
study if this protein in Influenza C has any relation with the proteins
in the other Infuenzas. We found three sequences, one of each virus, and
we aligned them with ClustalW.
By the results we can hypothesize that the origin of this protein in Influenza
C isn’t related with haemagglutinin in the others members of its family.
For this, we can suppose that the origin of this protein is horizontal
transference from its host.