Calicivirus pathogenic for swine: a new serotype isolated from opaleye Girella nigricans, an ocean fish.

A new calicivirus, designated San Miguel sea lion virus type 7 (SMSV-7), was isolated from fish and produced a disease condition identical to vesicular exanthema in experimentally infected swine. Serotype SMSV-7 was also isolated from four elephant seals and one sea lion trematode, whereas a second calicivirus serotype isolated from fish proved to be SMSV-6.

Calicivirus isolation and persistence in a pygmy chimpanzee (Pan paniscus).

What may be the first calicivirus isolate from any primate species, including man, was recovered from a herpesvirus-like lip lesion on a pygmy chimpanzee and then, 6 months later, from the throat of the same animal. The infected individual and its cage mates had circulating antibodies that were type-specific for this calicivirus. The agent was antigenically different from 30 other calicivirus serotypes and is tentatively designated primate calicivirus Pan paniscus type 1 (PCV-Pan 1).

Caliciviruses infecting monkeys and possibly man.

Caliciviruses have, for the 1st time, been shown experimentally to infect a primate. Twenty-four hours after being inoculated with San Miguel sea lion virus (SMSV), an African green monkey developed a febrile response and vesicular lesions at injection sites. Virus was recovered from lesion material 96 hours later and from the stool at 48 hours. Possible human infection with SMSV was indicated by serologic evidence. Three persons working with 4 distinct serotypes of SMSV developed neutralizing antibody titers to 2 SMSV types. The positive serum-neutralization test results were confirmed, using immunoelectron microscopy to demonstrate complexes of viruses and antibodies.

Calicivirus isolation from three species of primates: an incidental finding.

Calicivirus isolations were made from 3 species of subhuman primates. Viruses were recovered from gingival lesions associated with periodontal disease in a spider monkey, from the oropharynx of a healthy silver leaf langur, and from the spleen of a lowland gorilla that had died of systemic coccidioidomycosis. Based on the results of cross-neutralization tests, all 3 isolates were serologically indistinguishable from a primate calicivirus Pan paniscus type 1. These isolations appeared to be incidental in nature and could not be associated causally with any specific disease entity.

Isolation of San Miguel Sea Lion Virus from Samples of an animal food product produced from northern fur seal (Callorhinus ursinus) carcasses.

A virus was isolated from California sea lions (Zalophus californianus californianus) and northern fur seals (Callorhinus ursinus) in 1972. It was later named San Miguel sea lion virus (SMSV). State and federal livestock disease control agencies became concerned, because SMSV was found to be indistinguishable from vesicular exanthema of swine virus and to cause (in laboratory trials) clinical signs in swine similar to those produced by vesicular exanthema of swine virus. Ground carcasses of northern fur seals, salvaged after harvesting pelts, are fed to mink on ranches in the United States. Domestic swine are kept on some of these same ranches. Samples withheld from lots of this seal carcass mink food were found to contain SMSV (serotype 5) in titers of 10(6.1) and 10(6.8) tissue culture infective doses.

Immunoelectron microscopic comparisons of caliciviruses.

Using immunoelectron microscopy, 9 serotypes of vesicular exanthema of swine virus (VESV) were compared with 5 serotypes of San Miguel sea lion virus and 7 additional calicivirus isolates from marine animals. In addition, swine caliciviruses and marine caliciviruses were compared with the vaccinal strain of feline calicivirus (FCV) F-9. Of 9 VESV types, 8 showed common antigenicity with San Miguel sea lion virus. Of 9 VESV types, 2 showed common antigenicity with FCV F-9. All 12 marine caliciviruses showed common antigenicity with VESV, but not with FCV F-9.

Isolation and identification of five new serotypes of calicivirus from marine mammals.

Five new serotypes of calicivirus have been isolated from marine mammals. San Miguel sea lion virus (SMSV)-8 and SMSV-10 were recovered from vesicular lesions on the flippers of northern fur seals in the Pribilof Islands of Alaska. Serotype SMSV-9 was isolated from a sea lion in southern California, and SMSV-11 was isolated from 2 northern fur seal pups in southern California. Serotype SMSV-12 was also isolated in southern California from sea lion and fur seal pups.

Preliminary investigation of a possible lung worm (Parafilaroides decorus), fish (Girella nigricans), and marine mammal (Callorhinus ursinus) cycle for San Miguel sea lion virus type 5.

Colostrum-deprived neonatal Northern fur seal pups (Callorhinus ursinus) were exposed to San Miguel sea lion virus type 5 (SMSV-5) by feeding them fish (Girella nigricans) infected with virus or fish infected with both the sea lion lung worm larvae (Parafilaroides decorus) and virus. Virus infection was demonstrated in 8 of 9 pups, and 1 of these developed a vesicular lesion on the flipper. In this sequence, P decorus larvae exposed to SMSV-5 were fed to G nigricans held at 15 C in a salt water aquarium; 32 days later, these fish were killed, then fed to the fur seal pups. The vesicle developed 22 days subsequent to this and SMSV-5 was reisolated from the lesion. The SMSV-5 was shown to persist for at least 23 days in infected neonatal fur seals. Attempts to establish P decorus infection in Northern fur seal pups were apparently unsuccessful.

Isolation and identification of caliciviruses from dogs with enteric infections.

Caliciviruses were isolated from 7 dogs and 1 captured coyote with enteritis. There was a high fatality rate in dogs 4 to 16 weeks of age. The occurrence in these dogs of concurrent infection with known enteric pathogens such as Salmonella sp, canine parvovirus, canine coronavirus, and canine rotavirus did not allow making any conclusions regarding the pathogenicity of this newly recognized calicivirus. The caliciviruses were characterized by electron microscopy and were further identified as being closely related to feline calicivirus by immunoelectron microscopy with specific antibody.

Isolation and partial characterization of a calicivirus from calves.

A calicivirus was isolated from 3 dairy calves in a herd with persistent calf respiratory tract problems. This virus, named Tillamook calicivirus, was not neutralized by 18 different calicivirus-typing serums available. The agent caused only minimal lesions in 2 experimentally exposed calves, but did establish a persistent infection with virus shedding for 45 days, after which time the experiment was terminated. Experimentally exposed swine developed clinical vesicular lesions. The possible origins, disease potential, and relationships to the exotic animal disease agent, vesicular exanthema of swine are discussed for this first calicivirus isolate of bovine origin.

First isolation of calicivirus from reptiles and amphibians.

Calicivirus isolations were made from 4 poikilothermic species in a zoologic collection. Viruses were recovered from 8 asymptomatic Aruba Island rattlesnakes (Crotalus unicolor; rectal swab samples) and from 8 symptomatic animals (4 Aruba Island rattlesnakes, 2 Bell's horned frogs [Ceratophrys orata], 1 rock rattlesnake [C lepidus], and 1 eyelash viper [Bothrops schlegeli] tissue samples obtained at necropsy). On the basis of cross-neutralization test results, the 16 isolates were antigenically indistinguishable and were considered to represent a unique calicivirus serotype, tentatively designated reptilian calicivirus Crotalus type 1. These isolations could not be associated causally with any specific disease entity either in naturally infected poikilotherms or in experimentally infected snakes and pigs.

New marine calicivirus serotype infective for swine.

A new serotype of calicivirus was isolated from California sea lions (Zalophus californianus) with severe vesicular disease. Neutralizing antibodies were found in 27 of 82 (32.9%) serum samples from California sea lions and in 15 of 146 (10.3%) serum samples from Steller sea lions (Eumetopias jubatus) tested. The seropositive animals were widely dispersed along the margins of the eastern Pacific basin, from the Bering Sea to the Santa Barbara Channel. Seropositive samples were found from as early as 1976 through the present time. This new calicivirus serotype, San Miguel sea lion virus type 13, was inoculated into weaned pigs, resulting in induction of severe vesicular disease, which spread to all pigs, including uninoculated pen contacts. Virus was continually shed by most of the pigs throughout the 2-week duration of the experiment.

Prevalence and distribution of serum neutralizing antibodies to Tillamook (bovine) calicivirus in selected populations of marine mammals.

Neutralizing antibodies to Tillamook calicivirus (TCV) were found in sera collected from California sea lions (Zalophus c. californianus Lesson) in 1983 and 1984 and in sera collected from Steller sea lions (Eumetopias jubatus Schreber) in 1976 and 1985. The combined prevalence of antibodies for these two species was 10/228 = 4.38%. Titers ranged from 1:20 (five animals), to 1:40 (four animals), to 1:80 (one animal) by standard microtiter neutralization assay. The seropositive pinnipeds were dispersed widely along the margins of the eastern Pacific rim, from the Bering Sea to the Santa Barbara Channel. Antibodies to TCV were not found in sera collected from northern fur seals (Callorhinus ursinus L.), Pacific walruses (Odobenus rosmarus divergens Illiger), seals of the family Phocidae, or several cetacean species. Tillamook calicivirus was isolated originally in 1981 from dairy calves in Oregon; the finding of neutralizing antibodies in two widely distributed species of sea lions suggests the possibility of a marine origin for this agent.

Serology and virology of the bowhead whale (Balaena mysticetus L.).

Sera from four bowhead whales (Balaena mysticetus L.) were examined for the presence of specific antibodies, and tissue and swab samples from six and four animals respectively were processed for isolation of viruses and for initiation of bowhead whale cell cultures. All sera were negative for antibodies to nine serovars of Leptospira interrogans and to 21 orthomyxovirus subtypes and a paramyxovirus (Newcastle disease virus). All sera were positive, however, for neutralizing antibodies to one or more calicivirus serotypes. Two untyped adenoviruses were isolated from colon samples of two different whales, but neutralizing antibodies to the agents could not be demonstrated in any sera. Three primary bowhead whale cell cultures were derived from kidney (two cultures) and testis (one culture), from three individual whales.

First isolation of a calicivirus from the Steller sea lion (Eumetopias jubatus).

A calicivirus was isolated from the rectum of a Steller sea lion (Eumetopias jubatus) pup on Rogue Reef, off the southern Oregon coast. Based on the results of neutralization tests with specific typing antisera, the isolate was identified as San Miguel sea lion virus serotype 6 (SMSV-6). Blood obtained from nine of 37 pups (24%) during virus sample collection procedures had specific neutralizing antibodies to SMSV-6. The isolation of SMSV-6 from a Steller sea lion represents, to our knowledge, the first isolation of any virus from this widely distributed marine mammal species, and serves to reconfirm the host-nonspecificity of yet another calicivirus of marine origin.

Naturally-occurring leptospirosis in northern fur seals (Callorhinus ursinus).

A 4-year study of Northern fur seal (Callorhinus ursinus) leptospirosis in the Bering Sea has shown that in newborn pups Leptospira pomona is associated with a multiple hemorrhage syndrome. Adults may develop an interstitial nephritis and shed organisms in the urine. The hed prevalence, based on microscopic slide agglutination tests, ranged between 7.0% and 15.4% for adult females and 3-4 year old bachelor bulls, whereas nursing pups averaging 4 months of age had a prevalence of 2%. These results are used to conclude that leptospirosis is not acquired primarily on the breeding rookeries but rather is more frequently acquired subsequent to the purps leaving the rookeries, presumably through the food chain during their first pelagic cycle.

Antibodies to marine caliciviruses in the Pacific walrus (Odobenus rosmarus divergens Illiger).

Sera from 155 Pacific walruses (Odobenus rosmarus divergens Illiger), sampled in the Chukchi Sea during the summer of 1983, were tested for serum neutralizing (SN) antibodies to six marine calicivirus serotypes. Serotypes tested included San Miguel sea lion virus (SMSV) types 1, 5, 8, and 10, previously isolated from northern fur seals (Callorhinus ursinus Linné) in the Bering Sea; walrus calicivirus (WCV), previously isolated from walrus feces collected off sea ice in the Chukchi Sea; and Tillamook calicivirus (TCV), a bovine isolate from Oregon of suspected marine origin. No antibodies were found to SMSV-1, SMSV-10, or TCV. Antibodies to SMSV-5 were found in two animals (titers 1:20 and 1:160); antibodies to SMSV-8 were found in four animals (all 1:20); and antibodies to WCV were found in one animal (titer 1:40). Antibodies to WCV have been found in the Pacific walrus previously; however, this represents the first report of antibodies to any of the SMSV serotypes in this marine mammal.

Detection of a non-cultivatable calicivirus from the white tern (Gygis alba rothschildi).

In April 1992, on Tern Island, French Frigate Shoals, Hawaii (USA), researchers observed a hand-reared white tern hatchling (Gygis alba rothschildi) develop vesicular lesions on the webbing between its toes, 6 days after falling out of its nest. Vesicular fluid collected from the foot lesions contained virus-like particles having typical calicivirus morphology. Calicivirus RNA was detected in the vesicular fluid by dot hybridization with a group-specific calicivirus copy DNA probe. Attempts to cultivate the virus in African green monkey kidney cells and porcine kidney cells were unsuccessful. This is the first report of a calicivirus infection associated with vesicular disease in a wild avian species.

Mortality of harbor seal pups at different sites in the inland waters of Washington.

We examined the mortality rates and causes of death of harbor seal (Phoca vitulina) pups in three regions of the inland waters of Washington (USA) in 1984. One hundred eight pups were collected during 239 searches of the shoreline areas near harbor seal haulout sites or through public reports. Minimum neonatal (up to 1 mo after birth) mortality rates at these regions ranged from 12% to 26% of the pups born. Neonatal mortality was highest in the Strait of Juan de Fuca; 33 of the estimated 105 (31%) pups born at the primary site died. Causes of death varied by location. In southern Puget Sound predation by coyotes (Canis latrans) was the primary cause of death, accounting for eight of 43 (19%) of the dead pups examined; starvation was the next most common cause of death. Mortality at study sites in the Strait of Juan de Fuca was related to premature parturition; 19 of 49 (39%) of the pups found dead were born prematurely. Nine species of bacteria were identified in samples taken from 42 pups; Proteus sp. and Escherichia coli were the most common.

Isolation of reptilian calicivirus Crotalus type 1 from feral pinnipeds.

Ten virus isolates were obtained from three species of marine mammals sampled on San Miguel Island (California, USA) and 1,200 km north on Rogue Reef (Oregon, USA) during tagging operations in 1986-87. Seven of these 10 were derived from 30 sampled Steller sea lion (Eumetopias jubatus pups, while two of 10 were isolated from one of 19 sampled California sea lion (Zalophus californianus californianus pups, and the remaining isolate was derived from 30 sampled northern fur seal (Callorhinus ursinus) pups. All 10 isolates were identified as belonging to a single serotype, reptilian calicivirus Crotalus type 1 (RCV Cro-1), previously isolated from both healthy and diseased snakes and frogs in a California zoologic collection. The marine samples also showed that nine of 30 Steller sea lion pups, one of 19 California sea lion pups and zero of 30 fur seal pups were producing type specific neutralizing antibodies to RCV Cro-1. This represents the first reported instance of the isolation from marine sources of calicivirus originally isolated from a terrestrial species.