Infectious Bursal Disease*

[en_route]

как перевести след. предложение, помогите пож-та:
"Variants are not from a different serotype, are antigenically different enough to cause problems."
контекст ниже...пасиб!

Prevention & Control of INFECTIOUS BURSAL DISEASE
- Variants cause rapid bursal atrophy without inflammation and edema
- Variants are not from a different serotype, are antigenically different enough to cause problems
- Consider vaccinating breeders with inactivated vaccines containing standard and variant strains of IBD virus