key: cord-0004961-x5wx9f1n
authors: Evermann, J. F.; Smith, A. W.; Skilling, D. E.; McKeirnan, A. J.
title: Ultrastructure of newly recognized caliciviruses of the dog and mink
date: 1983
journal: Arch Virol
DOI: 10.1007/bf01311109
sha: 61c589556ee878dac6d167367a6e5df1634c3ade
doc_id: 4961
cord_uid: x5wx9f1n

Two recently recognized viruses obtained from a dog with glossitis and from mink with hemorrhagic pneumonia were characterized by electron microscopy. The results of the negative-stained preparations indicated that the viruses were structurally compatible with the calicivirus group.

Two recently recognized viruses obtained from a dog with glossitis and from mink with hemorrhagic pneumonia were characterized by electron microscopy. The results of the negative-stained preparations indicated that the viruses were structurally compatible with the eMicivirus group. , During studies on the pathogenesis of hemorrhagic pneumonia syndrome in mink, viruses were isolated and initially reported as picornaviruses on the basis of physicochemical criteria. (6) . This report presents the ultrastructure of this virus, as well as that of another recently recognized calicivirus isolated from a dog with glossitis and gingivitis (4).

The mink virus (MV 20-3) was grown in Vero cells and had a titer of 105.s TCIDs0 per ml. The canine glossitis virus (WSU 79-1831) was grown in Crande]l feline kidney (CrFK) cells and had a titer of 105.3 TCID50 per ml. Specimen preparation for electron microscopy consisted of inoculation of a roller tube of either Vero cells or CrFK cells with 0.1 ml of the respective stock virus. After 1 hour incubation, cell culture medium was added and the tubes incubated at 37°C on a roller drum. When the cells showed 3-}-cytopathogenic effect the tubes were frozen and thawed one time and centrifuged at 2000 × g for 10 minutes. An aliquot (480 ~l) of supernatant from the tube was further clarified by centrifugation in a Beckman Airfuge 30 ° fixed angle rotor at 23,000 x g for 5 minutes. The virus-containing supernatant was then centrifuged in the aforementioned apparatus at 165,000 × g for 10 minutes. The pelleted virus was resuspended in 50 ~l of distilled water and was pelleted directly onto a carbon coated gI~d using the Beckman Airfuge E~-90 rotor at 118,000 Xg for l0 minutes. The grids were stained with 1.5 percent phosphotungstic acid for i minute, blotted dry, and examined with a Philips 300 transmission electron microscope at 80 kV. The viruses were sized by using a stock culture of tobacco mosaic virus for internal size standardization. The mink calicivirus (MV 20-3) had exhibited properties consistent with the ealicivirus family in earlier studies (6) . These features included: physieochemical properties; growth in Vero cells; and electron microscopy of cell-associated virus particles. The results from this study confirmed that the virus was structurally related to the calicivirus family. The virus particles were approximately 35--40 nm in diameter with a patterned dark staining surface (Fig. 1) . Higher magnification revealed t0 evenly spaced cup-shaped depressions on the periphery of the virions (Fig. 2) .

The canine glossitis virus (WSU 79-1831) had been previously shown to be antigenically related to feline calicivirus on the basis of serum neutralizing tests (4) . The electron microscopic studies reported herein (Fig. 3) indicated that the virion structure was also consistent with the Caliciviridae Family (9, 14) .

These studies served to substantiate the reports of calicivirus infections of mink and dogs and they can be added to an ever expanding list of caliciviruses now recognized to infect humans, primates, foxes, calves, fish, and chickens (2, 5, 7, 10, 1] ., 12, t3, 15) . Of interest with both of these recently recognized ealieiviruses is their origin and pathogenesis in their natural host. Since mink are customarily fed marine by-products (8) (8) . However, the m i n k calieivirus (MV 20-3) was shown not to be antigenically related to the ten SMSV serotypes available at t h a t time (6). On the basis of seroepizootiologie d a t a infection b y the mink calicivirus is widespread in the m i n k p o p u l a t i o n (6) . While associated ~dth hemorrhagic p n e u m o n i a of mink, the virus has not been shown e x p e r i m e n t a l l y to cause disease in mink. F u r t h e r studies are necessary to determine if the mink calicivirus predisposes m i n k to Pseudomonas aeruginosa infection as has been proposed (6) .

The canine glossitis virus was isolated in 1979 coincident with a world-wide epizootic of canine p a r v o v i r u s (CPV), which was the cause of myocarditis and enteritis in susceptible wild and domestic eanids (1, 3). Once it was d e t e r m i n e d t h a t CPV was antigenieally related to feline panleukopenia the use virus vaccines of feline origin containing F P L virus in dogs was encouraged in an effort to control the CPV infection (1).

However, since some of the virus vaccines of feline origin also contained modified live feline calicivirus and feline herpesvirus together with F P L virus, it, remains a possibility that, the canine glossitis virus was t r a n s m i t t e d from a dog receiving modified bye feline calieivirus in combination with F P L virus. Additional studies are necessary to determine the pathogenesis of the canine glossitis virus in susceptible dogs and cats.

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