VP7蛋白在病毒的各蛋白中最保守，是病毒的血清群特异性抗原。
VP7, the most conserved protein of the virion, is serogroup-specific antigen.
BA法染色表明法氏囊一直存有病毒和群特异性抗原，以接毒后3～4个月含量最高。
There were lymphoid leukosis virus and group specific antigen in the follicles with BA dying which was highest in content from the 3rd to 4th month of PI.
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