[Antigenic properties of variants of the influenza virus H7N7 and its recombinants]

Passages of the A/seal/Massachusetts/1/80 strain in different biological systems (chick embryos, mice, chickens, organ cultures of human embryo trachea) yielded variants differing from the original virus both in their biological and antigenic properties. The M20 variant selected in passages of the seal virus in mouse lungs differed from the latter only in biological but not antigenic properties. The OC20 and C20 variants produced by passages of the seal virus in organ cultures and chicken lungs differed from the original virus only antigenically. The antigenic properties were examined by the HI test using monoclonal antibodies to the A/seal/Massachusetts/1/80 strain. In addition, the HI test with the selected variants and individual clones of the seal virus as well as recombinants produced with this virus revealed variability of the epitope of hemagglutinin reacting with monoclone 71/4. Because mice, chickens and chick embryos had no specific antibodies to the A/seal/Massachusetts/1/80 strain, a conclusion is drawn on the possibility of antigenic variability of influenza A virus in nonimmune hosts.