Serological, biochemical and structural properties of three bovine picornaviruses.

Three viral agents isolated from nasal exudate of Illinois cattle affected with respiratory disease were studied. The agents were classified as picornaviruses on the basis of their resistance to ether, stability at pH 3.0, and morphological characteristics. Magnesium chloride at 1 M concentration protected the viruses from reduction of infectivity by exposure to 50 degrees C for one and two hours. None of the viruses was pathogenic for mice. Replication of one of the viruses was not affected by the DNA inhibitor, 5 fluorodeoxyuridine. That two of the agents were closely related serologically was demonstrated by serum neutralization tests. As revealed by electron microscopy, viral particles were spherical or hexagonal and ranged in size from 280 A to 290 A.