Effect of maternally acquired Aujeszky's disease (pseudorabies) virus-specific antibody in pigs on establishment of latency and seroconversion to differential glycoproteins after low dose challenge.

This study investigated whether (1) passively immune pigs could become latently infected after challenge with low doses of wild type pseudorabies virus (PRV) and (2) if seroconversion to PRV could be consistently detected using two commercially available differential diagnostic ELISAs. Three litters of piglets with passively acquired PRV serum neutralizing (SN) antibody (geometric mean titers 47.03 to 95.10) were challenged at 6 to 12 days of age with 236 to 500 TCID50 of Shope strain virus; pigs were vaccinated at 11 weeks of age with a commercially available genetically engineered vaccine (TK- gE- gG- Iowa S62 strain PRV). Vaccination was intended to reduce the risk of reactivation of latent infection resulting in spread of virulent PRV infection to previously uninfected pigs during the experiment. Vaccination at this age also approximated common field practices in infected herds. After 15 weeks, all challenged pigs were seropositive on the PRV glycoprotein (g or gp) E differential ELISA but were seronegative on the gG differential ELISA. All three challenge groups had pigs that were latently infected as evidenced by the detection of PRV DNA by polymerase chain reaction (PCR) assay of their trigeminal ganglia (TG). There was a significant inverse relationship observed for age at challenge and the proportion of PCR positive pigs in the group 15 weeks postchallenge (p = 0.0004). This trend was independent of the passively acquired PRV SN antibody titers at challenge. In this study, passively acquired antibody did not provide protection against establishment of latent infection in piglets after exposure to low doses of virulent PRV. These latent infections were detected serologically by only one of two available differential diagnostic ELISA.

Phenotypic and ribosomal RNA characterization of Arcobacter species isolated from porcine aborted fetuses.

Aerotolerant organisms resembling Campylobacter, now designated as Arcobacter, have been described from aborted farm animals and from cases of human enteritis worldwide. The goals of this study were 1) to attempt to recover Arcobacter spp. from cases of porcine abortion, 2) to characterize these isolates by phenotype and ribotype, and 3) to compare the usefulness of ribotype and phenotype patterns for identifying Arcobacter butzleri and the DNA hybridization groups 1A and 1B of A. cryaerophilus. Isolates of Arcobacter spp. from North Carolina and Iowa were recovered from porcine tissues. In Iowa, Arcobacter spp. were recovered from 43% (13/30) of porcine abortion cases evaluated. Isolations were made from placenta (44%), kidney (44%), and stomach contents (12%), which were the only tissues examined. The most reliable biochemical tests for A. butzleri included growth in 1% glycine and in 1.5% NaCl, weak catalase activity, and resistance to cadmium chloride. Arcobacter cryaerophilus strains were characterized by strong catalase activity and sensitivity to cadmium chloride. The DNA hybridization groups 1A and 1B of A. cryaerophilus could not be distinguished by biochemical tests. This represents the first description of A. cryaerophilus DNA group 1A in animals within the United States.

Volatile organic compounds in the breath of patients with schizophrenia.

AIMS: To analyse the breath of patients with schizophrenia for the presence of abnormal volatile organic compounds. METHODS: A case comparison study was performed in two community hospitals in Staten Island, New York. Twenty five patients with schizophrenia, 26 patients with other psychiatric disorders, and 38 normal controls were studied. Alveolar breath samples were collected from all participants, and volatile organic compounds in the breath were assayed by gas chromatography with mass spectroscopy. Differences in the distribution of volatile organic compounds between the three groups were compared by computerised pattern recognition analysis. RESULTS: Forty eight different volatile organic compounds were observed in the breath samples. Three separate pattern recognition methods indicated an increased differentiation capability between the patients with schizophrenia and the other subjects. Pattern recognition category classification models using 11 of these volatile organic compounds identified the patients with schizophrenia with a sensitivity of 80.0% and a specificity of 61.9%. Volatile organic compounds in breath were not significantly affected by drug therapy, age, sex, smoking, diet, or race. CONCLUSIONS: Microanalysis of volatile organic compounds in breath combined with pattern recognition analysis of data may provide a new approach to the diagnosis and understanding of schizophrenia. The physiological basis of these findings is still speculative.

Prevalence of pseudorabies (Aujeszky's disease) virus antibodies in feral swine in Florida.

Serum samples collected from feral swine (Sus scrofa) throughout Florida (USA) from 1980 to 1989 were tested for antibodies to pseudorabies virus (PRV) by the serum neutralization test, the latex agglutination test, or by the enzyme-linked immunosorbent assay. Seropositive swine were detected at 11 of 13 sites with a composite seroprevalence of 34.8% (579 of 1,662 samples; range = 5.9% to 58.2%) for sites with seropositive swine. Data on age and sex of the swine were available from three sites. Seroprevalence in males and females did not differ significantly (P = 0.62 for the combined data). Seroprevalence in adult (> or = 8 mo) and juvenile swine (< 8 mo) was significantly different at all sites (P < 0.05 for the combined data). From these data, PRV infections appear to occur widely in populations of Florida feral swine and may seriously undermine efforts to eradicate this virus from the domestic swine population of the USA.

Viral contamination of fetal bovine serum used for tissue culture: risks and concerns.

Four viral contaminants have been routinely detected in unprocessed and commercial lots of fetal bovine serum: bacteriophage, infectious bovine rhinotracheitis, parainfluenza-3 and bovine viral diarrhea virus (BVDV). Of those, BVDV is consistently present in a majority of commercial lots of fetal bovine serum. Methods for BVDV detection and removal are reviewed. The tentative role of an unclassified pestivirus in microcephaly of infants has been reported. Its significance remains uncertain.

In vivo and in vitro genetic recombination between conventional and gene-deleted vaccine strains of pseudorabies virus.

Pseudorabies virus (PRV), an alpha-herpesvirus, causes substantial economic losses in the swine industry and is currently the focus of eradication and control programs. Some of these programs rely on the ability of veterinarians to differentiate animals exposed to virulent strains of PRV from animals exposed to avirulent vaccine strains of PRV on the basis of a serologic response to nonessential glycoproteins that are deleted in some vaccine strains of PRV. Genetic recombination resulting in the creation of virulent strains of PRV with the same negative immunologic markers as vaccine strains could disrupt these programs. Two strains of PRV were coinoculated either into tissue culture or into sheep to facilitate recombination. Progeny viruses were selected to detect a specific recombinant phenotype. We were able to detect genetic recombination between vaccine strains of PRV following in vitro or in vivo coinoculation of 2 strains of PRV. The selected recombinants had marker-deleted phenotypes in strains with restored virulence genes. Increased virulence was observed in sheep after coinoculation of 2 avirulent vaccine strains of PRV.

Serum antibody prevalence of parainfluenza 3 virus in a free-ranging bison (Bison bison) herd from Alaska.

Serum antibody prevalence of parainfluenza 3 virus in the free-ranging Delta bison (Bison bison) herd which is found near Delta Junction, Alaska (USA), increased from 0% to 100% during the period 1977 to 1984. Domestic cattle are hypothesized as the source for the infection. There has been no clinical disease or decrease in productivity in this bison herd since establishment of the infection.

Recombination in vivo of pseudorabies vaccine strains to produce new virus strains.

Herpesvirus suis (pseudorabies virus, PRV) has been the focus of intensive genetic engineering efforts and several effective genetically recombinant modified live virus PRV vaccines have resulted. The likelihood and consequences of complementation and/or genetic recombination in vivo between genetically engineered and conventionally derived vaccine strains of PRV are essentially unknown. In this study, two vaccine strains of PRV with complementary gene deletions were co-inoculated into sheep. It reports that avirulent vaccine strains of PRV (genetically engineered and conventionally attenuated) recombined in vivo, resulting in the production of a new and undesirable strain of PRV. The present study exemplifies the need for thorough assessment of genetically engineered micro-organisms in the animal environment.

Isolation of vesicular stomatitis virus New Jersey serotype from phlebotomine sand flies in Georgia.

Vesicular stomatitis virus New Jersey serotype (VSNJ virus) was isolated from 6 of 610 pools of phlebotomine sand flies (Lutzomyia shannoni) collected on Ossabaw Island, GA. All isolates were from non-blooded females. Infected sand flies were collected at 6 sites at 5 separate times from 3 June through 25 July 1988. Thirty-five pools of Culicoides ssp. and 48 pools of mosquitoes obtained in conjunction with the infected sand flies also were evaluated for VSNJ virus; all were negative. Concomitant serologic monitoring of sentinel swine indicated that VSNJ virus transmission began in late April and continued through the completion of this study in August. The incidence of seroconversion among the sentinel wild swine was 50%. Domestic sentinel swine did not seroconvert at 2 sentinel sites, 1 of 2 seroconverted at 1 site, and 2 of 2 seroconverted at the fourth site. Vesicular lesions were seen on 10 sentinel wild swine during the summer. Vesicular stomatitis virus (NJ) was isolated from 4 of these swine and was diagnosed in 1 additional swine by direct complement-fixation assay. The time period within which VSNJ virus was isolated from sand flies preceded detection of vesicular lesions but corresponded with the period of seroconversion in sentinel swine. Site specific data indicated that VSNJ virus activity was widespread within the study area.

Reactivation of latent pseudorabies virus infection in vaccinated commercial sows.

Pseudorabies virus (PRV) was isolated from 9 of 44 PRV-vaccinated seropositive sows on 5 of 11 farms. Although serum-neutralization antibody titers were 1:16 to 1:256, 28 virus isolates were obtained from tonsil, nasal, or buccal swab samples from 9 sows given 2 ml of dexamethasone/kg of body weight IM for 5 days. Pseudorabies virus was isolated from 6 of 20 sows (3 of 5 farms) given a killed-virus vaccination. Virus was obtained from 3 of 24 sows (2 of 6 farms) given modified-live virus and killed-virus vaccination. Evaluation of the 9 PRV with 5 restriction endonucleases revealed 4 PRV existing genotypes. The 9 isolated types of PRV appeared to be indistinguishable by Kpn I and BamHI restriction endonuclease analysis; however, when analyzed with Sal I, HinfI, and Pst I, isolates 7 (farm D), 8 (farm C), and 9 (farm B) had numerous differences. Isolates 1, 2, 3, and 4 (farm F) and 5 and 6 (farm G) appeared to be the same genotype when further analyzed with Pst I, HinfI, and Sal I.

A survey of wild swine in the United States for evidence of hog cholera.

The results of surveillance for hog cholera (HC) in wild swine (Sus scrofa) collected from throughout the United States from 1979 to 1987 are presented. Sera collected from 1,218 wild swine and tissues from 637 were evaluated for HC antibodies and virus, respectively. Included within this surveillance were samples from Santa Cruz and Santa Rosa Islands, California, where HC virus had been deliberately introduced into wild swine during the 1950's in attempts to eradicate these animals. All evaluations were considered negative for HC. It appears that the HC virus does not maintain itself in dispersed swine populations and that wild swine have not remained a reservoir of HC since its eradication in domestic swine in the United States.

Immunological surveillance in a pseudorabies quarantined herd using gilts and their progeny as sentinels.

Specific pathogen free gilts and their progeny were evaluated to use as sentinels in a pseudorabies virus (PRV) infected herd by immunologically monitoring for PRV seroconversions. Time intervals targeted were pre- and post-PRV vaccinations, herd exposure, and farrowing to finishing. Post-PRV vaccinations, gilts showed low PRV lymphocyte stimulation and humoral responses. Following herd exposure, control gilts PRV seroconverted and PRV vaccinated gilts increased (2 to 4 times) in virus neutralization (VN) titers. Sixty-seven percent (4/6) of the progeny from a control gilt were PRV seropositive at finishing. Progeny from PRV vaccinated gilts were depleted of passive immunity by week 7, and were seronegative until week 9. At finishing 47% (14/30) of them were PRV seropositive indicating exposure to PRV. The VN test was not sensitive enough to detect weak positive serums, noted as positives by latex agglutination (LA) test, ELISA, and Western blots. The gilts and progeny detected PRV, respectively, in the herd housing quarters and in the farrow to finish facilities. A strategy for future sentinel experimental surveillances using primarily the LA test is proposed.

Detection and elimination of adventitious agents in continuous cell lines.

The National Veterinary Services Laboratories (NVSL) routinely monitors continuous cell lines (CCL's) used for veterinary biologicals and diagnostic virology. All veterinary biologicals produced in CCL's must follow the master seed concept which limits the use of the master seed CCL to up to 20 passages beyond the passage level characterized and deposited at NVSL. All CLL's are evaluated for the presence of adventitious agents such as mycoplasma, bovine viral diarrhea virus, and other bacteria and viruses. Previously, CCLs were evaluated for tumorigenicity by the Syrian hamster cheek pouch method; however, this procedure has now been eliminated. The adventitious agents most frequently detected in CCL's have been bovine viral diarrhea virus and mycoplasma. Our laboratory has consistently found that the source of bovine viral diarrhea contamination of CCLs has been the use of contaminated fetal bovine cell culture enrichment serum. Gamma irradiation at 2.5-3.5 megarads at -40 degrees C of carefully screened fetal bovine serum has been used in the Diagnostic Virology Laboratory for over 10 years. If the irradiated serum is used at a final concentration of 10 percent, there is no untoward effect on cell susceptibility for virus propagation or cell culture growth. Gamma irradiation has also been demonstrated to be a very efficient inactivator of mycoplasma. Specific conditions utilized by our laboratory to preserve fetal bovine serum cell culture growth factors while eliminating adventitious bovine viral diarrhea virus will be presented.

Serum neutralizing antibody titers in dairy cattle administered an inactivated vesicular stomatitis virus vaccine.

Two doses of a formalin-killed, cell culture-derived vesicular stomatitis virus (vsv)-New Jersey serotype vaccine were administered intramuscularly, 30 days apart, to all lactating and nonlactating cows in a 350-cow dairy herd. Serum specimens were obtained serially from 96 cows before vaccination and at 30, 52 and 80 days after vaccination and from 24 of these cows 175 days after vaccination. Serum neutralizing antibody titers to vsv-New Jersey serotype were determined from serum-dilution, plaque-reduction tests. Serum neutralizing antibody titers also were determined during the same period for 67 nonvaccinated heifers in the herd. Peak group geometric mean serum neutralizing antibody titers of 1:530.46 +/- 1.14 (group geometric mean titer log10, 2.725 +/- 0.055) developed 21 days after the second vaccination, but decreased to a low value of 1:65.36 +/- 1.38 (group geometric mean titer log10, 1.815 +/- 0.142) by 175 days after vaccination. The nonvaccinated group had no detectable antibody titer to vsv-New Jersey serotype throughout the study. All serum specimens from the vaccinates and controls were negative for heterologous reactivity to vsv-Indiana serotype.

Serologic survey for evidence of exposure to vesicular stomatitis virus, pseudorabies virus, brucellosis and leptospirosis in collared peccaries from Arizona.

Two hundred eighteen usable serum samples were collected from hunter-killed collared peccaries (Tayassu tajacu) during March 1986, in three areas of Arizona. Evaluations for antibodies against vesicular stomatitis virus (VSV) New Jersey (NJ) type, VSV Indiana type, pseudorabies virus, brucellosis, and leptospirosis revealed positive test results in 8%, 0%, less than 1%, 0%, and 23% of the sera, respectively. Exposure of peccaries to VSV (NJ) was widespread, but variation in the prevalence of seropositive peccaries was not found between the three areas sampled. The exposure of peccaries to VSV (NJ) probably was related to the recent epizootics in livestock in the vicinity. Exposure to Leptospira interrogans serovars also was widespread, and geographic variation in the prevalence of peccaries with antibodies against L. interrogans was found.

Antibodies to vesicular stomatitis New Jersey type virus in wild and domestic sentinel swine.

Wild sentinel swine on Ossabaw Island, Chatham County, Georgia, were serially bled and tested for vesicular stomatitis New Jersey type virus neutralizing antibody to determine the intensity, distribution, and progression of annual viral activity. From March through September, 1984 and 1985, 112 and 226 juvenile (less than 8 months) swine, respectively, were sampled. Seroconversions initially were detected on May 7, 1984 and May 18, 1985. Incidence of seroconversion in wild swine reached 32% during 1984 and 26% during 1985. Viral activity as determined by seroconversion results occurred earliest and was greatest on the southern half of Ossabaw Island. Domestic swine were housed in four pens under controlled conditions to document arthropod transmission of vesicular stomatitis virus. Twelve swine, three in each pen, were serially bled from April through September of both years. Seroconversion occurred during May 16-23, 1984 and May 15-22, 1985. Results varied among pen locations but were consistent between years. Clinical disease was not seen in any wild or domestic swine during either year.

Effects of gamma-irradiation on isolated rat liver mitochondria.

Gamma-irradiation of isolated rat liver mitochondria with doses of up to 475 Gy leading to hydrated electrons (G = 1.9, corrected for reaction with solutes), 30 Gy leading to carbohydrate radicals, (G = 5.6), 100 Gy leading to superoxide radicals (G = 6.2), and 130 Gy leading to formate radicals (G = 6.2) showed, within the error of the measurements, no effects on the rate of oxygen uptake in the various respiratory states, the respiratory control ratio, or the adenosine diphosphate to atomic oxygen ratio. Typical values obtained were 0.020-0.100 nmol O2 s-1 mg protein-1 for State 1 respiration, 0.25-0.33 nmol O2 s-1 mg protein-1 for State 4 respiration and 0.65-1.10 nmol O2 s-1 mg protein-1 for State 3 respiration. Typical respiratory control ratios ranged from 2.0-3.5 for succinate and 4.0-6.5 for a 1:1 glutamate: malate substrate mixture. Adenosine diphosphate to atomic oxygen ratios with succinate as substrate varied from 1.6 to 1.9. Because these results are unexpected, in situ and in vitro irradiated mitochondria were examined in an electron microscope and compared to mitochondria in situ, non-irradiated mitochondria and mitochondria isolated after whole liver irradiation. Irradiation of isolated mitochondria with 375 Gy results in the partial destruction of the mitochondrial outer membrane with no significant changes in respiratory rates.

Survey of selected diseases in wild swine in Texas.

Tissue, fecal, and serum specimens and swabs of nasal turbinates and tracheas were collected from 100 wild swine (Sus scrofa) from 10 populations in Texas and, along with 24 additional serum specimens, were evaluated for selected swine diseases. Swine positive for pseudorabies were detected in 7 populations. Brucella suis biovar 1 was isolated from 4 swine from 2 populations, but positive serologic results may indicate a more widespread distribution of the organism. All populations contained swine that were positive for leptospirosis. Trichinella spiralis was not found in the swine evaluated.