Understanding the dynamics of the selection of influenza A immune escape variants by serum antibody is critical for designing effective vaccination programs for animals, especially poultry where large populations have a short generation time and may be vaccinated with high frequency. In this report, immune-escape mutants of A/turkey/New York/4450/1994 H7N2 low pathogenic avian influenza virus, were selected by serially passaging the virus in the presence of continuously increasing concentrations of homologous chicken polyclonal sera. Amino acid mutations were identified by sequencing the parental hemagglutinin (HA) gene and every 10 passages by both sager and deep sequencing, and the antigenic distance of the mutants to the parent strain was determined. Progressively, a total of five amino acid mutations were observed over the course of 30 passages. Based on their absence from the parental virus with deep sequencing, the mutations appear to have developed de novo. The antigenic distance between the selected mutants and the parent strain increased as the number of amino acid mutations accumulated and the concentration of antibodies had to be periodically increased to maintain the same reduction in virus titer during selection. This selection system demonstrates how H7 avian influenza viruses behave under selection with homologous sera, and provides a glimpse of their evolutionary dynamics, which can be applied to developing vaccination programs that maximize the effectiveness of a vaccine over time.

了解通过血清抗体选择 A 型流感免疫逃逸变体的动态对于为动物设计有效的疫苗接种计划至关重要，尤其是在数量众多、世代时间短且可能接种频率高的家禽中。在这份报告中，A/turkey/New York/4450/1994 H7N2 低致病性禽流感病毒的免疫逃逸突变体是通过在不断增加浓度的同源鸡多克隆血清的情况下连续传代病毒来选择的。通过对亲本血凝素 (HA) 基因进行测序并通过 sager 和深度测序每 10 次传代来鉴定氨基酸突变，并确定突变体与亲本菌株的抗原距离。逐步，在 30 次传代过程中总共观察到 5 个氨基酸突变。基于深度测序不存在亲本病毒，突变似乎已经发展从头开始。所选突变体与亲本菌株之间的抗原距离随着氨基酸突变数量的积累而增加，并且必须定期增加抗体浓度以在选择过程中保持相同的病毒滴度降低。该选择系统展示了 H7 禽流感病毒在使用同源血清进行选择的情况下如何表现，并提供了其进化动态的一瞥，可用于开发疫苗接种计划，以最大限度地提高疫苗的有效性。