Viruses used in serological studies.

Unless otherwise indicated serologic study was performed using the microneutralization technique.
Viruses were selected from among our virus library considering their H type, and their year and geographical area of collection for the closest match with viruses likely to be circulating in Cambodia. Unfortunately, we did not have a large collection of viruses from Cambodia from which we might choose. *Virus studied with hemagglutination inhibition assay; †Virus of avian origin; ‡Highly pathogenic virus.