These data indicate the viruses detected in respiratory specimens from this patient are closely related to existing HPAI A(H5N1) CVVs that are already available to manufacturers, and which could be used to make vaccines if needed.
There were some differences detected between the NP/OP and the NP specimens. Despite the very close similarity of the D1.1 sequences from the Louisiana human case to bird viruses, deep sequence analysis of the HA gene segment from the combined NP/OP sample detected low frequency mixed nucleotides corresponding to notable amino acid residues (using mature HA sequence numbering):
- A134A/V [Alanine 88%, Valine 12%];
- N182N/K [Asparagine 65%, Lysine 35%]; and
- E186E/D [Glutamic acid 92%, Aspartic Acid 8%].
The NP specimen, notably, did not have these low frequency changes indicating they may have been detected from swabbing the oropharyngeal cavity of the patient. While these low frequency changes are rare in humans, they have been reported in previous cases of A(H5N1) in other countries and most often during severe disease
2345. The E186E/D mixture, for example, was also identified in a specimen collected from the severe human case detected in British Columbia, Canada.