did you know ?
One key reason for this discrepancy is that HIV-1 is one of the most genetically diverse viruses known. The HIV-1 diversity within just one infected person at any one time is as great as the diversity of influenza viruses worldwide in an entire year. For example, there are as many as four genetic groups of HIV-1, nine subtypes and 55 circulating recombinant forms, or forms that have swapped their genetic material. This extensive genetic diversity has limited our ability to rapidly and cost-effectively sequence HIV-1 genomes from different populations and geographical regions.
I also didn't know that plus the diversity of human influenza viruses is numbered ~90,000. I must admit that I have had always assumed that microbial genomes are easy to work with but the diversity within a species itself sounds like it might be a mind boggling task!