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.

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.

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.

Neutralising antibodies to rinderpest virus in wild animal sera collected in Kenya between 1970 and 1981.

Four hundred and twenty five sera were collected from 18 species of wild mammals in Kenya between 1970 and 1981. Neutralising activity to rinderpest virus (RV) was detected in 35 samples from 13 species. This activity appeared to be specific antibody to RV since it did not neutralise the virus of peste des petits ruminants. It was associated with the serum globulin fraction and it blocked the staining of a rabbit immunofluorescent antibody conjugate to RV. Positive sera were not restricted to any particular area of Kenya. It is possible that strains of RV with low pathogenicity and low transmissibility are still present in wildlife in East Africa, a fact which must be considered when studying the epidemiology and control of rinderpest.

Isolation and identification of African horsesickness virus from naturally infected dogs in Upper Egypt.

African horsesickness virus was isolated from blood samples of street dogs in Aswan Province in Arab Republic of Egypt. Of six isolated "dog strain" African horsesickness viruses, three viruses designated D2, D6 and D10 have been identified as type 9 African horsesickness virus. Methods of isolation, tissue culture adaptation, serological indentification and typing are described. Horses experimentally infected with dog viruses showed febrile reaction and characteristic clinical and pathological signs of African horsesickness. Reisolation of African horsesickness virus type 9 was achieved from the horses during serial passages.

Malignant catarrhal fever III. Experimental infection of sheep, domestic rabbits and laboratory animals with malignant catarrhal fever virus.

Five of 19 sheep became infected when inoculated with a virulent strain of malignant catarrhal fever virus isolated in Kenya One of the infected animals was killed in extremis; its blood and lymph node suspension reproduced the classical disease in three steers. Calves exposed to these sheep did not become infected during 89 days of close contact. The Kenya strain of malignant catarrhal fever virus infected rabbits, guinea pigs and hamsters, producing occular and nasal discharges, paralysis and death. The virus recovered from these animals in cell cultures produced disease in rabbits and steers. Neutralizing antibodies were found in the rabbit sera. Infant mice, chicken and duck embryos were refractory to infection with malignant catarrhal fever virus.

Malignant catarrhal fever. I. Response of American cattle to malignant catarrhal virus isolated in Kenya.

Fifty-three American cattle were inoculated with malignant catarrhal fever virus isolated from a wildebeest in Kenya. Three animals showed the mild form of the disease and recovered, and 47 showed the severe form of the disease. The other three did not react. Of the 47 cattle, 28 died, 16 were killed for the collection of specimens and three recovered. The incubation period for the 47 cattle ranged from 16 to 29 days and the course of the fatal disease for 28 cattle averaged three to 23 days. Virus titration of specimens from nine infected steers yielded a mean titer of 10(4)/TCID50 per gm for lymph nodes, 10(3) TCID50 per mL for buffy coats and 10(2.3) TCID50 per gm for spleens. Smaller amounts of virus were found in the liver, kidneys, adrenals and thyroids. Malignant catarrhal fever virus was also found in nasal secretions and saliva of viremic cattle. Viral infectivity was shown in bovine buffy coat cells stored at 4 degrees C for two days but was immediately destroyed upon freezing even when glycerine or dimethylsulfoxide was added. Viral particles were not found in infected animal tissues by electron microscopy. The disease was successfully transmitted in steers by intratracheal intubation and by aerosol inhalation but not by contact.

Un metodo simplificado para la deteccion de anticuerpos contra la fiebre porcina africana, mediante la inmunoelectroosmoforesis. / A simplified method for the detection of african swine fever antibodies by immunoelectroosmophoresis

Se han elaborado equipos con nuevo diseno y procedimientos que permiten detectar con mayor rapidez las precipitinas contra el virus de la fiebre porcina africana. La metodologia se puede aplicar tambien en el diagnostico de la hepatitis y en otros procedimientos electroforeticos. La gran reduccion de los costos hace estos metodos accesibles a los laboratorios pequenos

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.

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.

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.

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.