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.

Vesicular exanthema of swine virus: isolation and serotyping of field samples.

Virus isolation was attempted from 262 field samples of vesicular material collected during the outbreaks of vesicular exanthema of swine in the U.S.A. from 1952-54. Using primary swine kidney culture, viral cytopathogenic agents were isolated from 76.3% of the samples. However, an overall recovery rate of 82.1% was obtained after samples negative in tissue culture were inoculated intradermally in susceptible swine. All vesicular exanthema of swine virus isolates were identified as serotype B51 using complement fixation and serum neutralization tests. Two isolates did not react with antisera to known vesicular agents of swine and failed to produce vesicles or clinical signs of disease upon inoculation in swine. One vesicular exanthema of swine virus isolate from tissue of equine origin was pathogenic for swine but produced limited vesiculation at the site of intradermalingual inoculation in the tongue of a pony infected experimentally. Type B51 virus was reisolated from lesions produced in the pony and the pony became seropositive for virus type B51.

Duck viral enteritis (duck plague) characteristics and immune response of the host.

Duck viral enteritis (DVE) is caused by a herpesvirus whose biologic and physical characteristics are similar to those described for the group of herpesviruses. Only one immunologic and serologic type is known. A low level of neutralizing antibodies is developed in waterfowl vaccinated with the chicken embryo attenuated DVE virus. A marked anamnestic serologic response resulted from challenge with virulent virus. Waterfowl resisting exposure with virulent virus were solidly immune. However, waterfowl which possessed moderate level of neutralizing antibodies succumbed when their immunity was challenged with virulent virus when secondary or latent microbial invaders were present. This may partially explain the lack of correlation between the levels of neutralizing antibodies and mortality from infection with DVE virulent virus.

Clinical and immunologic responses of pigs to African swine fever virus isolated from the Western Hemisphere.

Pigs in the United States were exposed to African swine fever (ASF) virus isolated from pigs in Brazil and the Dominican Republic. The former were examined for clinical response, lesions, viremia, and antibody response. Sequential blood samples were tested for the presence of ASF virus by the hemadsorption test (in swine buffy coat cell culture) and for antibody to ASF virus by the enzyme-linked immunosorbent assay. The incubation period was 3 to 5 days; inoculated pigs had fever for 8 to 16 days (mean 12.5 days) and viremia at 3 to 35 days after inoculation and few died. Inoculated pigs developed antibodies at 7 days after inoculation which were detectable until the termination of the experiment (10th month). Reinoculation of some of the surviving pigs with the homologous isolate at approximately 6 months after exposure did not induce clinical response, viremia, nor anamnestic antibody response. In contrast, challenge exposures of convalescent pigs with the Lisbon-60 viral strain approximately 5 weeks after exposure to the Brazilian strain produced death, in spite of an anamnestic antibody response.

Western hemisphere isolates of African swine fever virus: asymptomatic carriers and resistance to challenge inoculation.

Convalescent clinically normal pigs were tested for the persistence of African swine fever (ASF) infection. One group of pigs was examined 135 days after inoculation with a Brazilian isolate and a 2nd group was examined 110 days after inoculation with a Dominican Republic isolate. Susceptible pigs exposed by contact to these groups remained clinically normal. These contact pigs plus 2 more pigs added to each group developed ASF after being fed and inoculated with tissues collected from recovered pigs. African swine fever virus was not isolated in swine buffy coat cultures inoculated with supernatant fluid from the collected tissues. The remaining convalescent Brazilian and Dominican Republic ASF pigs were challenge inoculated with homologous virus and then with Lisbon 60 ASF virus. Pigs in both groups remained clinically normal after homologous virus challenge inoculation. Pigs in the Brazilian group remained clinically normal after inoculation of the lisbon 60 ASF viral isolate. Of 5 pigs in the Dominican Republic group, 3 developed a transient viremia after inoculation of the Lisbon 60 ASF viral isolate.

Contagious equine metritis: isolation and characterization of the etiologic agent.

Uterine, cervical, and clitoral specimens on swabs from pony mares infected with contagious equine equine metritis (CEM) bacteria were streaked on agar plates. Colonies of CEM bacteria were observed under CO2 incubation in 2 days on Eugon chocolate agar and Eugon blood agar plates. The diameter of the colonies varied from 0.2 mm to 1 mm in 2 days which increased to 0.3 mm to 2.0 mm on day 4. The colonies on Eugon chocolate agar plates on days 2 to 4 were shiny, brown, round, and convex, and easily glided when pushed with a loop. The diameter of the colonies on chocolate and blood agar plates made from tryptose blood agar base (TrCA or TrBA) was 0.2 to 0.3 mm on day 4. Due to their small size on TrCA or TrBA, colonies of CEM bacteria were easily recognized from large numbers of contaminants. The organism required hemin for its growth. It gelled in water, caused delayed hemolysis of blood agar plates, and was extremely susceptible to acid in the pH range to 3 to 4.5. A difference in growth of CEM bacterium was observed on primary isolation media obtained from two different commerical sources.

Contagious equine metritis: effect of intrauterine inoculation of contagious equine metritis agent in pony mares.

Actively growing culture of contagious equine metritis (CEM) bacteria or infective exudate (or both) were inoculated intrauterine in pony mares. A direct relationship was observed between (i) appearance and duration of cervicitis and vaginitis and (ii) vaginal exudate. Clinical signs appeared 1 to 3 days after mares were inoculated and lasted 7 to 23 days. In the acute phase of infection, all uterine and cervical samples yielded CEM bacteria. In the asymptomatic stage of infection, CEM bacteria were not isolated from uterine and cervical samples; however, in 33%, 28%, and 20% of the pony mares, CEM bacteria were present in clitoral fossa, clitoral sinus, and urethral vestibule, respectively, Sampling during early estrus increased the bacterial isolation rate to 57% in mares that were previously negative; however, 3 days later, CEM bacteria could not be isolated from 62% of the positive mares. The results of repeated exposure experiments indicated the presence of local antibodies, as no CEM bacteria could be recovered at 2, 7, and 15 days after reexposure with a small number of bacterial cells (8.4 x 10(5) cells). The CEM bacteria were isolated from all mares reexposed with a large number of bacterial cells (7.2 x 10(8)) at 2 days after second inoculation and from 50% at 7 days. However, all of the mares were negative by day 15 after reexposure, indicating increased resistance to CEM bacteria.

Survival of contagious equine metritis bacteria in transport media.

Survival of bacteria that cause contagious equine metritis (CEM) was evaluated in Amies modified transport (AMT) medium, in AMT medium with charcoal, and in Stuart transport medium at 37, 22, 4, and -70 C. The CEM bacteria suspended in transport media survived at 22, 4, and -70 C for longer periods in AMT medium with charcoal than they did in AMT and Stuart transport media. In 1 day, the number of bacteria in exudate stored in the absence of any transport medium decreased 15-fold at 22 C and twofold at 4 C. The CEM bacteria were isolated from exudate on cotton-tipped swabs from all three transport media at 4 and -70 C on day 10, the termination of the experiment. However at 4 C, the survival of CEM bacteria was greater in AMT medium with charcoal than it was in AMT and Stuart transport media.

Comparison of African and American forms of malignant catarrhal fever: transmission and clinical signs.

African and American forms of malignant catarrhal fever (MCF) infections were produced by inoculating blood from affected cattle into susceptible cattle. Ease of disease transmission, incubation period, volume of blood required for infection, and clinical signs were compared in 30 cattle with African MCF and in 19 with American MCF. American MCF was more difficult to transmit than was African MCF and required eight to ten times more blood as inoculum. American MCF incubation period was more than twice as long as that of the African MCF, but the disease course was three times shorter. Clinical signs were similar for the two forms; however, in the American form, the disease was more acute and a larger percentage of animals had severe diarrhea.

Susceptibility of mink to certain viral animal diseases foreign to the United States.

Mink (Mustela vison) were inoculated with viruses: African horse sickness (AHS), African swine fever (ASF), bovine herpes virus II (BHV2), foot-and-mouth disease (FMD), goat pox (GP), hog cholera (HC), peste des petits ruminants (PPR), rinderpest (RP), swine vesicular disease (SVD), vesicular exanthema of swine (VES) and vesicular stomatitis (VS). Their susceptibility was measured by development of clinical signs, virus isolation and detection of precipitin and/or virus neutralizing antibodies. SVD virus produced a lesion in one mink. Virus was isolated from mink inoculated with SVD, FMD and BHV2. Neutralizing and/or precipitin antibodies were detected in mink inoculated with ASF, FMD, GP, RP, SVD and VS viruses. Mink were not susceptible to AHS, HC, PPR and VES viruses.

Response of white-tailed deer to infection with peste des petits ruminants virus.

White-tailed deer (Odocoileus virginianus) were infected experimentally with two strains of peste des petits ruminants virus. The response varied from fatal consequence to subclinical infection. The clinical signs and gross lesions were similar to those in goats. Virus was recovered from all the infected deer, and survivors developed specific antibodies demonstrated by complement fixation and virus neutralization tests. Survivors also resisted challenge with virulent rinderpest virus that was lethal to a control deer.

Susceptibility of white-tailed deer to experimental heartwater infections.

Nine white-tailed deer (Odocoileus virginianus) were experimentally infected with Cowdria ruminantium, the causal agent of heartwater. All deer developed clinical signs; one was killed, one was treated, and seven died within 2 wk postinoculation. Diagnosis of heartwater was based on clinical signs, postmortem lesions and by microscopic observation of C. ruminantium in endothelial cells of brain capillaries of dead animals. Cowdria ruminantium was passaged by collecting blood from deer at the height of the febrile response and intravenous inoculation of susceptible deer and goats. Tetracycline was effective in the treatment of heartwater in a deer.

Experimental infection of white-tailed deer with rinderpest virus.

White-tailed deer (Odocoileus virginianus) succumbed to experimental infection with virulent rinderpest (RP) virus that was also lethal to cattle and goats. The deer developed clinical signs typical of RP and died 5 and 6 days post-inoculation. Infection was confirmed by recovery of virus from blood before death, from lymph node tissue after necropsy, and demonstration of specific complement fixing antigen in those tissues. Electron micrographs of infected Vero cell cultures revealed extracellular virions and intracytoplasmic and intranuclear inclusions made of randomly distributed fibrillar strands.

Contagious equine metritis: clinical description of experimentally induced infection.

Contagious equine metritis was reproduced experimentally in 6 pony mares. The disease was characterized by rapidly developing cervicitis and by varying amounts of exudate. The exudate, apparent as early as 48 hours after inoculation, drained from the cervix as a tenacious, mucopurulent discharge for several days, then rapidly disappeared. In all mares, the clinical disease cleared within several weeks of inoculation, without treatment.