Extracción de virus

Purification, Morphology and Partial Characterization of a Reovirus-like Agent Associated with Neonatal Calf Diarrhea
Ardyce B. Welch*

SUMMARY

RESUME

Studies have been conducted on a virus L'auteur a etudie un virus recemment imwhich has recently been implicated as an plique comme agent etiologique de nombreux etiological agent in widely disseminated cases cas disperses de diarrhee chezles veaux. Il a of calf diarrhea. The virus was isolated from isole ce virus du fumier et de la muqueuse feces and intestinal mucosa from experimental- intestinale de veaux infectes experimentalely infected calves and from cell cultures which ment et de cultures cellulaires inoculees avec had been inoculated with material from in- du materiel provenant de veaux infectes. Il a fected calves. Thevirus was purified by dif- purifie le virus au moyen de l'ultracentrifuferential centrifugation, nuclease treatment, gation, du traitement aux nucleases, de l'exextraction with Genetron 113 and cesium traction au Genetron 113 et du gradient au chloride (CsC1) gradient. Purified and non- chlorure de ce'sium (CsCl). Il a etudie, ia l'aide purified samples were studied by electron du microscopeetlectronique, des etchantillons microscopy. Both types of preparations con- purifie's et non purifie's du virus. Les deux tained unenveloped particles approximately 64 variite's d'etchantillons contenaient des partinm in diameter with a hexagonal core region cules d'environ 64 nm de diametre, d6pourvues 36 nm in diameter. Subunits of the capsids ap- d'enveloppe et pre'sentant une region centrale pearedto be arranged in accordance with cubic hetxagonale d'un diametre de 36 nm. Les soussynmetry. Essential lipids were not associated unites des capsides semblaient dispose'es selon with the virus. The buoyant density of purified une syme'trie cubique. Aucun lipide essentiel virus was 1.359. Viral nucleic acid was deter- n'e'tait associe' au virus. La densite' de flottamined by chemical methods tobe ribonucleic tion du virus purifie' e'tait de 1.359. L'identiacid (RNA). The morphology and some chem- fication de l'acide nucle'ique du virus, par des ical characteristics appear to be similar to mthodes chimiques, a re'vele qu'il s'agissait those of the reovirus group. However, the de l'acide ribonucle'ique (RNA). La morphoexact classification of this virus and its rela- logie et d'autrescaracteres chimiques semblent tionship to other groups remains to be estab- comparables 'a ceux du groupe reovirus. II reste cependant 'a pretciser la classification du lished. virus et ses relations avec les autres groupes.
*Department of Veterinary Science, University of Nebraska, Lincoln, /Nebraska 68503. Published with the approval of the Director as Paper No. 2884, Journal Series, NebraskaAgricultural Experiment Station. The work reported was conducted under Nebraska Agricultural Experiment Station project No. 14-1. The investigation reported in this paper was supported in part by a grant from the U.S. Department of Agriculture; Agricultural Research Service (No. 1214-100-10, 610 (45)). Submitted December 7, 1970.

INTRODUCTION
Infectious diarrhea remains a majcr disease problem ofcalves today. Viruses, such as bovine virus diarrhea and infectious bovine rhinotracheitis, have been implicated

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as causative agents of diarrhea in calves (1, 16). Occasionally other viruses have been isolated from calves during epizootics and have been assumed to be etiological agents (16, 19, 20). However, proof of pathogenicity is difficult because thesame viruses have been isolated from apparently healthy carriers. Mebus et al (12) experimentally produced diarrhea in calves by inoculation with bacteria-free filtrates prepared from feces obtained from diarrhetic calves. Viral particles were detected in preparations partially purified by differential centrifugation and pelleted through a sucrose density gradient. However, the virus was not...