It turned out there is a flu-database at NCBI.
Hopefully it will help you.
I just looked inside the paper below.
But gisaid-database is not reachable without permission.
I hope it may be a probable solution to your problem.
Please, look at this paper below and at the table inside:
You will find many if not all known flu-epedemy HAs there.
As well as the viruses where they are from. I've already seen some of them
in NCBI FLU-database, so you have a chance.
It was so interesting to me that I've started the work for you.
I've searched for HA in NCBI FLU-database.
I found about 6000 partial sequences of HA like this one below.
And occasionally I found the following url: ftp://ftp.ncbi.nih.gov/genomes/INFLUENZA/
Look at it. It seems useful. To my mind it contains currently known flu genomic information from NCBI.
Below is an example of my search in the FLU-database in NCBI.
- I've found a fragment of HA in aminoacids from some Influenza A virus with different ids. etc.
hemagglutinin, partial [Influenza A virus (A/Afghanistan/AF1168/2008(H3N2))]
GenPept Identical Proteins Graphics
gi|187606959|gb|ACD13250.1| hemagglutinin, partial [Influenza A virus (A/Afghanistan/AF1168/2008(H3N2))]