The JMK strain of infectious bronchitis virus caused respiratory disease outbreaks in chickens despite vaccination with the Massachusetts strain.
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May indicate Mass vaccine mismatch against JMK IB; leaves open need for strain-specific poultry vaccines.
Infectious bronchitis (IB) virus was isolated from a large number of cases of respiratory disease in Connecticut chickens. Eight isolates were all characterized as the JMK strain of IB. Most cases occurred in flocks that were well vaccinated with Massachusetts strain IB vaccine and, where tested, exhibited good virus-neutralizing serum titers. Histopathologic lesions in the trachea in acute cases consisted mainly of epithelial hyperplasia with little or no edema or mononuclear infiltration, a lesion pattern that is described as typical of Newcastle disease (ND). However, no ND infections were found in these cases of IB.
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Heide et al. (1973) studied this question.
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