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At least 19 recordsLinked to original sources
PubMed1955

The swine lungworm as a reservior and intermediate host for swine influenza virus. V. Provocation of swine influenza by exposure of prepared swine to adverse weather.

Twenty-five swine, infested with lungworms infected with masked swine influenza virus, were exposed to adverse weather conditions on one or more occasions. Of these, 4 came down with apparent swine influenza, while 6 others developed serological evidence of infection with swine influenza virus. The remaining 15 prepared swine, as well as 8 lungworm-free control swine, failed to show evidence of swine influenza virus infection, despite repeated exposures to adverse weather. The data presented indicate that, in the 10 swine in which swine influenza virus infections were elicited, some feature of the weather to which the animals were exposed was responsible for provoking masked influenza virus to infectivity. The exact constituent of the meteorological complex comprising "weather", responsible for the provocation, cannot be determined from the data obtained.

Animals↗
PubMed1998

The African swine fever virus thymidine kinase gene is required for efficient replication in swine macrophages and for virulence in swine.

African swine fever virus (ASFV) replicates in the cytoplasm of infected cells and contains genes encoding a number of enzymes needed for DNA synthesis, including a thymidine kinase (TK) gene. Recombinant TK gene deletion viruses were produced by using two highly pathogenic isolates of ASFV through homologous recombination with an ASFV p72 promoter-beta-glucuronidase indicator cassette (p72GUS) flanked by ASFV sequences targeting the TK region. Attempts to isolate double-crossover TK gene deletion mutants on swine macrophages failed, suggesting a growth deficiency of TK- ASFV on macrophages. Two pathogenic ASFV isolates, ASFV Malawi and ASFV Haiti, partially adapted to Vero cells, were used successfully to construct TK deletion viruses on Vero cells. The selected viruses grew well on Vero cells, but both mutants exhibited a growth defect on swine macrophages at low multiplicities of infection (MOI), yielding 0.1 to 1.0% of wild-type levels. At high MOI, the macrophage growth defect was not apparent. The Malawi TK deletion mutant showed reduced virulence for swine, producing transient fevers, lower viremia titers, and reduced mortality. In contrast, 100% mortality was observed for swine inoculated with the TK+ revertant virus. Swine surviving TK- ASFV infection remained free of clinical signs of African swine fever following subsequent challenge with the parental pathogenic ASFV. The data indicate that the TK gene of ASFV is important for growth in swine macrophages in vitro and is a virus virulence factor in swine.

African Swine Fever↗
PubMed2002

Antibody levels to hepatitis E virus in North Carolina swine workers, non-swine workers, swine, and murids.

In a cross-sectional serosurvey, eastern North Carolina swine workers (n = 165) were compared with non-swine workers (127) for the presence of antibodies to hepatitis E virus as measured by a quantitative immunoglobulin enzyme-linked immunosorbent assay. Using a cutoff of 20 Walter Reed U/ml, swine-exposed subjects had a 4.5-fold higher antibody prevalence (10.9%) than unexposed subjects (2.4%). No evidence of past clinical hepatitis E or unexplained jaundice could be elicited. Swine (84) and mice (61), from farm sites in the same region as exposed subjects, were also tested. Antibody prevalence in swine (overall = 34.5%) varied widely (10.0-91.7%) according to site, but no antibody was detected in mice. Our data contribute to the accumulating evidence that hepatitis E may be a zoonosis and specifically to the concept of it as an occupational infection of livestock workers.

Agricultural Workers' Diseases↗
PubMed1999

An African swine fever virus ORF with similarity to C-type lectins is non-essential for growth in swine macrophages in vitro and for virus virulence in domestic swine.

An African swine fever virus (ASFV) ORF, 8CR, with similarity to the C-type lectin family of adhesion proteins has been described in the pathogenic isolate Malawi Lil-20/1. The similarity of 8CR to cellular and poxvirus genes associated with cell adhesion, cell recognition and virus infectivity suggested that 8CR may be of significance to ASFV-host cell interactions. Sequence analysis of the 8CR ORF from additional pathogenic ASFV isolates demonstrated conservation among isolates from both pig and tick sources. Northern blot analysis demonstrated 8CR mRNA transcription late in the virus replication cycle. A Malawi Lil-20/1 8CR deletion mutant (delta8CR) was constructed to analyse 8CR function further. The growth characteristics in vitro of delta8CR in porcine macrophage cell cultures were identical to those observed for parental virus. In domestic swine, delta8CR exhibited an unaltered parental Malawi Lil-20/1 disease and virulence phenotype. Thus, although well conserved among pathogenic ASFV field isolates, 8CR is non-essential for growth in porcine macrophages in vitro and for virus virulence in domestic swine.

African Swine Fever↗
PubMed1996

A swine SINE (PRE-1 sequence) distribution in swine-related animal species and its phylogenetic analysis in swine genome.

The distribution of PRE-1 sequence (a swine SINE) among the animal species related to Sus scrofa, i.e. Phacochoerus aethiopicus and Tayassu tajacu, was examined by dot-blot analysis using PRE-1 sequences as a probe. This revealed that Phacochoerus aethiopicus and Tayassu tajacu contained PRE-1 sequences, amounts of which in their genomes are almost the same as that in the swine genome, indicating that these species separated after PRE-1 sequences proliferated to diversify in the genome. In order to estimate the time when the PRE-1 started to diversify in the swine genome, PRE-1 sequences were extracted from GenBank DNA database by homology analysis using the PRE-1 consensus sequence as a probe. The 22 PRE-1 sequences obtained were aligned and their phylogenetic relation was calculated by the neighbour-joining method. The result of the calculation combined with the mutation rate of the pseudogenes (r = 4.6 x 10(-9)) indicated that the PRE-1 sequence diversified at least 43.2 million years ago. Taken together, the period of time since the separation of the three species, Sus scrofa, Phacochoerus aethiopicus and Tayassu tajacu, is currently estimated to be less than 43.2 million years.

Animals↗
PubMed2002

Swine fever: classical swine fever and African swine fever.

Because of the clinical and pathologic similarity to common endemic diseases, introduction of CSFV or ASFV strains of moderate to low virulence represents the greatest risk to North American swine herds. Producers, veterinarians, and diagnosticians should increase their awareness of these devastating diseases and request specific diagnostic testing whenever they are suspected. Production practices that improve biosecurity will reduce the risk of introduction of CSF and ASF and limit the spread if an incursion occurs. Additional resources. The following Web sites contain excellent color photographs that will assist producers and practitioners in identifying clinical signs and gross lesions associated with CSFV and ASFV: http://www.vet.uga.edu/vpp/gray_book/FAD and http://www.pighealth.com. The latter Web site and the OIE Web site (http://www.oie.int) offer updated information on current worldwide epizootics of ASF and CSF and other swine diseases. Details of biosecurity procedures can be found at http://www.agebb.missouri.edu; see publication G2340.

African Swine Fever↗
PubMed1983

[Experimental swine influenza. Comparison of the pathogenicity of swine-type wild influenza viruses and strains of human type H3 N2 whose reservoir is swine].

Intra-nasal inoculation of 10-day-old piglets, free of specific pathogenic flora, with swine influenza virus A/H1 N1 and A/H3 N2 produces lesions of viral pneumonia without detectable clinical signs. Following indirect contamination all the strains studied were able to multiply in the respiratory tract; in those cases where no macroscopic lesion was seen, microscopic examination revealed variable modification of the pulmonary tissue depending on the virus causing infection. Influenza virus type H3 N2 are naturally found in many groups of pigs and can therefore play an important role in the respiratory pathology of the hog. Experimental results when compared to findings in the field indicate that the severity of the disease is linked to associated etiological factors as well as to the virulence of the viral strains themselves.

Animals↗
PubMed1981

Induction of swine dysentery in swine by the intravenous injection of filtered Treponema hyodysenteriae.

Swine dysentery was induced in 18 swine exposed by intravenous injection of a filtrate which contained Treponema hyodysenteriae and was obtained from macerated colonic scrapings of swine dysentery. However, swine dysentery did not develop in swine injected intravenously with a pure culture of T. hyodysenteriae or when combined with a colonic filtrate from normal swine. Diarrheal feces from the swine injected intravenously with the filtered T. hyodysenteriae contained more mucus, and fecal smears contained more T. hyodysenteriae and fewer other bacteria than did swine exposed orally to colon infected with swine dysentery or filtered T. hyodysenteriae. In the colons of the 12 swine injected intravenously with filtered T. hyodysenteriae that died, there was a minimum amount of croupous membrane and, microscopically, the T. hyodysenteriae were located deep in the colonic crypts. Five of the six surviving swine injected intravenously with filtered T. hyodysenteriae developed serum anti-T. hyodysenteriae antibodies using the indirect fluorescent antibody test and four of these swine developed diarrhea when reexposed with swine dysentery infected colon six weeks after initial exposure. None of the swine injected intravenously with cultured T. hyodysenteriae developed serum anti-T. hyodysenteriae antibodies and all were highly susceptible to swine dysentery.

Animals↗
PubMed1983

Cell-mediated immune reactivity of Sinclair melanoma-bearing swine to 3 M KCl extracts of swine and human melanoma.

Leukocyte migration inhibition (LMI) assays were performed using 3 M KCI extracts to detect cell-mediated immune reactions against tumor-associated antigens (TAA) of swine melanoma. Positive LMI reactivity was 70% or greater in melanoma-bearing swine compared to 10% reactivity or less in normal swine tested with extracts of either fresh or tissue-cultured swine melanoma cells. Positive LMI reactivity was 10% or less in both melanoma and normal swine tested with extracts of normal fetal and adult swine tissues. Extracts of tissue-cultured swine melanoma and human melanoma cells were equally capable of stimulating positive LMI reactivity in melanoma swine and human melanoma patients; normal swine and human donors demonstrated 10% or less positive LMI reactivity to these extracts. Positive LMI reactivity was not stimulated in swine melanoma or human melanoma donors by extracts of tissue-cultured human breast tumor cells or fresh and tissue-cultured mouse B16 melanoma cells. Evaluation of these results indicate that melanoma-bearing swine develop cell-mediated immune reactivity toward TAA on swine melanomas and, inasmuch as LMI assays were performed with allogeneic extracts, suggests the presence of common TAA on swine melanomas. Furthermore, these data suggest that swine and human melanoma cells may share some common TAA and that this common TAA is not expressed on mouse B16 melanoma cells.

Animals↗
PubMed2003

Identification of swine hepatitis E virus (HEV) and prevalence of anti-HEV antibodies in swine and human populations in Korea.

The swine hepatitis E virus (HEV) is considered to be a new zoonotic agent due to its close genomic resemblance to the human HEV and its ability to infect nonhuman primates. Hepatitis caused by HEV infection has been a serious public health problem in developing countries. However, recent seroprevalence studies indicate that the HEV also circulates in industrialized countries. In this study, a nested reverse transcription (RT)-PCR was developed to detect a part of the swine HEV open reading frame 2. Three Korean isolates of swine HEV were identified in 128 swine sera (2.3% prevalence) by the nested RT-PCR method. They were isolated from 2- to 3-month old pigs showing an age-specific prevalence of the HEV viremia. A phylogenetic tree analysis with a number of swine and human HEV isolates indicated that all Korean isolates of the swine HEV belong to genotype III. They were closely related to the swine and human HEV isolates that were identified in the United States and Japan. In addition, they formed a distinct branch in genotype III, showing a 92.7 to 99.8% identity at their nucleotide sequences. The overall prevalence of anti-swine HEV antibodies in swine was 15%. Antibodies to the swine HEV were not detected in 1-month-old pigs. However, the anti-swine HEV antibodies appeared in pigs older than 1 month and also showed an age-specific prevalence. The antibody prevalence rates to the swine HEV were 6.0, 10.0, 36.0, and 25.0%, in 2-, 3-, 4-, and 5-to-7-month-old pigs, respectively. In addition, the seroprevalence in sows to the swine HEV was 8.8%. On the other hand, 18% of blood donors in Korea were found to be positive for anti-HEV antibodies. Overall, this study indicates that subclinical HEV infections may prevail in swine and human populations in Korea.

Animals↗
PubMed1999

Enhancement of swine progenitor chimerism in mixed swine/human bone marrow cultures with swine cytokines.

OBJECTIVE: The induction of transplantation tolerance across xenogeneic barriers by bone marrow transplantation holds great promise, but engraftment of xenogeneic stem cells has been difficult to achieve. Part of this difficulty is due to species-specific differences in regulatory cytokines and elements of the stromal microenvironment, which we studied here. MATERIALS AND METHODS: We developed a system where fresh bone marrow cells from swine and human are cultured on human bone marrow stroma in order to study these limiting factors in a clinically relevant species combination. RESULTS: We report here the ability of recombinant swine interleukin (IL)-3 and c-kit ligand (KL) to specifically enhance swine hematopoietic chimerism in this system. In the absence of exogenous swine cytokines, there were about half as many swine progenitors as human progenitors at 1, 2, and 4 weeks of culture. When used alone, swine IL-3 led to a notable but transient increase in the relative ratio of swine progenitors, while addition of swine KL increased the ratio of swine progenitors only modestly and only at later time points. In contrast, when swine IL-3 and KL were added together, there was a two- to fourfold increase in the ratio of swine to human progenitors at all times tested. CONCLUSION: These data demonstrate that both swine IL-3 and KL are needed for prolonged enhancement of swine progenitor chimerism under these conditions, and suggest that the species specificity of either one or both of these cytokines may represent an important barrier to prolonged engraftment of swine bone marrow in humans.

Animals↗
PubMed1976

Prevention of swine dysentery with a combination of lincomycin and spectinomycin and resistance of swine dysentery to tylosin and sodium arsanilate.

The addition of a combination of lincomycin and spectinomycin to feed at the total concentrations of 44 and 77 mg/kg, beginning at the time of exposure and continuing for 8 weeks, prevented experimentally induced swine dysentery in swine. The disease did not develop after the medication was withdrawn. In contrast, swine dysentery, similar to that seen in the nonmedicated swine, did develop in simultaneously exposed swine treated with feed containing either 44 mg of tylosin or 99 mg sodium arsanilate/kg. The swine fed sodium arsanilate and which developed hemorrhagic diarrhea had a more severe form of this type of diarrhea than did the nonmedicated swine. After reexposure to inefective inoculum of swine dysentery 86 days after initial exposure, all remaining swine previously medicated with either tylosin or sodium arsanilate and all nonmedicated swine were immune; whereas 17 of the 24 swine fed the combination of lincomycin and spectinomycin were susceptible to swine dysentery and developed diarrhea.

Aniline Compounds↗
PubMed1990

Hematological and clinicochemical profiles of healthy swine and swine with inflammatory processes.

The hematological and clinicochemical profiles of healthy swine and swine with inflammatory processes were investigated. Blood was collected at slaughter and postmortem examination was performed to select healthy swine and swine with pleuritis, pneumonia or abscesses. In healthy swine, the values of several variables revealed significant differences between gilts, barrows and boars. This was caused predominantly by the values obtained for boars. Inflammatory processes altered the values of most variables investigated, particularly for erythrocyte sedimentation rate, hemoglobin and hematocrit, for the activity of alkaline phosphatase, and for concentrations of iron, phosphate, albumin and fibrinogen in plasma. Compared with healthy swine, differences were largest for swine with metastatic abscesses and swine with both abscesses and other pathological lesions; differences were less pronounced in swine with solitary abscesses and were minor in swine with pneumonia and swine with pleuritis. Porcine hematological and clinicochemical profiles reflect the degree of inflammation.

Abscess↗