Cross-protection test indicates that GM strain, JM strain and Ulster 2C strain could cross-protect each other.Chicken vaccinated with these vaccine strains could survive the challenge of GM strain.

• 攻毒保护性试验表明，GM株和JM株、Ulster 2C毒株之间具有免疫交叉保护性，使用这3种毒株作为疫苗毒进行免疫均能保护GM株强毒的攻击。