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PubMed1973

In vitro studies of group E streptococci in swine leukocytes. I. Phagocytic and bactericidal properties of polymorphonuclear leukocytes from swine.

Serum from both immune and nonimmune ten-week-old swine contained factors which promoted phagocytosis of group E Streptococci (GES). The factors in nonimmune serum, which were heat labile at 70 degrees C for ten minutes, were less efficient than the factors present in immune serum.Bactericidal activity of the polymorphonuclear (PMN) leukocytes against GES was observed with serum from both immune and nonimmune ten-week-old swine, as well as with serum from normal sows and piglets. However, the bactericidal activity of PMN leukocytes in serum from either normal sows or immune ten-week-old swine was greater than the bactericidal activity of PMN leukocytes in either piglet serum or serum from nonimmune ten-week-old swine. When the serum was either heated to 70 degrees C for ten minutes or treated with 2-mercaptoethanol, bactericidal activity of PMN leukocytes against GES was only observed in the presence of immune serum.

Animals↗
PubMed1981

Swine influenza virus in swine and man in Illinois.

Serum samples from 2,091 persons from Illinois populations of swine abattoir employees, 4-H Club youths and their advisors, veterinary medical students, pork producers, and veterinarians were tested for hemagglutination-inhibition (HI) antibodies to A/Swine/Ill./63. A total of 231 positive reactions of 1:20 or above were found (11%). The highest prevalence of antibody was found in veterinarians, followed by pork producers and future swine abattoir employees. Age-adjusted reactor rates were highest in pork producers. Of 305 abattoir employees from whom two serum samples were examined 26(8.5%) had positive seroconversions. The abattoir population studied consisted largely of males under 40 years of age. A low prevalence of antibody was found in veterinary medical students and none was found in 4-H Club youths having swine contact. It is postulated that in Illinois there is occupational exposure of veterinarians, pork producers, and swine abattoir employees.

Adolescent↗
PubMed2005

Mutation of E1 glycoprotein of classical swine fever virus affects viral virulence in swine.

Transposon linker insertion mutagenesis of a full-length infectious clone (IC) (pBIC) of the pathogenic classical swine fever virus (CSFV) strain Brescia was used to identify genetic determinants of CSFV virulence and host range. Here, we characterize a virus mutant, RB-C22v, possessing a 19-residue insertion at the carboxyl terminus of E1 glycoprotein. Although RB-C22v exhibited normal growth characteristics in primary porcine macrophage cell cultures, the major target cell of CSFV in vivo, it was markedly attenuated in swine. All RB-C22v-infected pigs survived infection remaining clinically normal in contrast to the 100% mortality observed for BICv-infected animals. Comparative pathogenesis studies demonstrated a delay in RB-C22v spread to, and decreased replication in the tonsils, a 10(2) to 10(7) log10 reduction in virus titers in lymphoid tissues and blood, and an overall delay in generalization of infection relative to BICv. Notably, RB-C22v-infected animals were protected from clinical disease when challenged with pathogenic BICv at 3, 5, 7, and 21 days post-RB-C22v inoculation. Viremia, viral replication in tissues, and oronasal shedding were reduced in animals challenged at 7 and 21 DPI. Notably BICv-specific RNA was not detected in tonsils of challenged animals. These results indicate that a carboxyl-terminal domain of E1 glycoprotein affects virulence of CSFV in swine, and they demonstrate that mutation of this domain provides the basis for a rationally designed and efficacious live-attenuated CSF vaccine.

Amino Acid Sequence↗
PubMed1999

Recovery of infectious classical swine fever virus (CSFV) from full-length genomic cDNA clones by a swine kidney cell line expressing bacteriophage T7 RNA polymerase.

A new method for the recovery of infectious classical swine fever virus (CSFV) from full-length genomic cDNA clones of the C-strain was developed. Classical reverse genetics is based on transfection of in vitro transcribed RNA to target cells to recover RNA viruses. However, the specific infectivity of such in vitro transcribed RNA in swine kidney cells is usually low. To improve reverse genetics for CSFV, a stable swine kidney cell line was established that expresses cytoplasmic bacteriophage T7 RNA polymerase (SK6.T7). A 200-fold increased virus titre was obtained from SK6.T7 cells transfected with linearized full-length cDNA compared to in vitro transcribed RNA, whereas transfection of circular full-length cDNA resulted in 20-fold increased virus titres. Viruses generated on the SK6.T7 cells are indistinguishable from the viruses generated by the classical reverse genetic procedures. These results show the improved recovery of infectious CSFV directly from full-length cDNAs. Furthermore, the reverse genetic procedures are simplified to a faster, one step protocol. We conclude that the SK6.T7 cell line will be a valuable tool for recovering mutant CSFV and will contribute to future pestivirus research.

Animals↗
PubMed2005

Preclinical diagnosis of African swine fever in contact-exposed swine by a real-time PCR assay.

A fluorogenic probe hydrolysis (TaqMan) PCR assay for African swine fever virus (ASFV) was developed and evaluated in experimentally infected swine. This sensitive and specific one-step single-tube assay, which can be performed in 2 h or less, detected viral DNA in tonsil scraping samples 2 to 4 days prior to onset of clinical disease. Thus, the assay would have application for preclinical diagnosis of African swine fever and surveillance and/or emergency management of a disease outbreak.

African Swine Fever↗
PubMed1999

African swine fever virus dUTPase is a highly specific enzyme required for efficient replication in swine macrophages.

The African swine fever virus (ASFV) gene E165R, which is homologous to dUTPases, has been characterized. A multiple alignment of dUTPases showed the conservation in ASFV dUTPase of the motifs that define this protein family. A biochemical analysis of the purified recombinant enzyme showed that the virus dUTPase is a trimeric, highly specific enzyme that requires a divalent cation for activity. The enzyme is most probably complexed with Mg(2+), the preferred cation, and has an apparent K(m) for dUTP of 1 microM. Northern and Western blotting, as well as immunofluorescence analyses, indicated that the enzyme is expressed at early and late times of infection and is localized in the cytoplasm of the infected cells. On the other hand, an ASFV dUTPase-deletion mutant (vDeltaE165R) has been obtained. Growth kinetics showed that vDeltaE165R replicates as efficiently as parental virus in Vero cells but only to 10% or less of parental virus in swine macrophages. Our results suggest that the dUTPase activity is dispensable for virus replication in dividing cells but is required for productive infection in nondividing swine macrophages, the natural host cell for the virus. The viral dUTPase may play a role in lowering the dUTP concentration in natural infections to minimize misincorporation of deoxyuridine into the viral DNA and ensure the fidelity of genome replication.

African Swine Fever↗
PubMed1982

The pathogenesis of vesicular exanthema of swine virus and San Miguel sea lion virus in swine.

Vesicular exanthema of swine virus type A48 or San Miguel sea lion virus type 2, when inoculated intradermally into swine, resulted in fluid-filled vesicles at the sites of inoculation in the snout, coronary band, and tongue. Pigs that developed vesicles also had fevers. Secondary vesicle formation varied, depending on virus serotype. Viremia was found in one pig infected with San Miguel sea lion virus five days after infection. Virus was recovered from nasal-oral passages for up to five days after infection in both groups of pigs and from the gastrointestinal and urinary tracts of pigs infected with San Miguel sea lion virus. Neutralizing antibodies began to increase three days after inoculation and reached peak titers in seven to ten days. In the absence of secondary bacterial infection, healing was well advanced by ten days after inoculation. Lesions usually were limited to nonhaired portions of the integument and tongue. Individual epithelial cells became infected when a break in the skin allowed virus access to susceptible epithelial cells from either exogenous or endogenous sources. Individual infected cells ruptured and adjacent cells were infected, resulting in the formation of multiple microvesicles. Centrifugal coalescence of microvesicles led to formation of grossly visible macrovesicles. Lesions rarely developed from viral contamination of intact hair follicles. A mild virus-induced encephalitis was seen in pigs infected with vesicular exanthema of swine virus, and virus was recovered from brain tissue of pigs infected with San Miguel sea lion virus.

Animals↗
PubMed1990

Relationships between the defensive systems of Iberian-breed swine and the European vector of African swine fever, Ornithodoros erraticus.

To discover whether the immune system of Iberian-breed pigs exerts any adverse action on Ornithodoros erraticus, 3 pairs of pigs were subjected to a weekly infestation over 12 wk with 1,000 larvae, 500 nymphs-1, or 200 adults. Each pair was bitten by only 1 developmental stage. Batches of parasites identical to the foregoing ones were fed weekly on control swine. In none of the 10 parameters studied for each of the batches fed weekly was any significant difference found that could be attributed to the state of sensitization of the animals in which, in a previous study, the presence of high titers of anti-O. erraticus antibodies was found. It was observed that the possible pruritus due to immediate hypersensitivity reactions, which in the test animals appeared after the third week, had no protective value in the natural milieu. In view of the inability of the swine to exert any control over the soft ticks, it is concluded that the size of their populations in the pig pens and their composition according to the developmental stage are factors that depend exclusively on the opportunities that swine breeders offer such populations to feed on the animals.

African Swine Fever↗
PubMed1993

Prophylactic application of Propionibacterium avidum KP-40 in swine with acute experimental infections. II. Bacterial infections: pleuropneumonia and swine erysipelas.

The potent immunomodifier Propionibacterium avidum KP-40 (PA) demonstrated prophylactic potency in swine infected experimentally with Haemophilus (Actinobacillus) pleuropneumoniae or Erysipelothrix rhusiopathiae. Animals received PA either together with the respective vaccine or PA only; 3 resp. 4 weeks later all animals were inoculated with virulent pathogens. Eight of 10 swine immunized with inactivated pleuropneumonia vaccine developed mild-moderate forms of infection with temporary stagnation of body weight; application of the vaccine together with PA lowered the morbidity rate to 1 of 10 (p < 0.05). Also in non-vaccinated swine infected with pleuropneumonia or erysipelas PA application resulted in milder clinical symptoms, faster recovery and a larger gain of body weight.

Actinobacillus Infections↗
PubMed2005

The effect of recombinant swine interleukin-4 on swine immune cells and on pro-inflammatory cytokine productions in pigs.

The in vitro effect and the in vivo influence of recombinant swine IL-4 (rSwIL-4) were characterized in various swine cells and in nursery pigs on LPS-induced endotoxic shock and pro-inflammatory cytokine productions. In in vitro experiment, the rSwIL-4 induced a proliferation of CD4 positive T cells in mitogen-prestimulated peripheral blood mononuclear cell (PBMC). In addition, the rSwIL-4, which was produced from insect cells, promoted the differentiation of monocytes into immature dendritic cells in combination with granulocyte macrophage-colony stimulating factor (GM-CSF). Furthermore, the rSwIL-4 successfully suppressed the LPS-induced secretion of TNF-alpha, IL-1alpha, IL-6, IL-8, and IL-18 from swine alveolar macrophages when rSwIL-4 was treated at the same time with LPS. In in vivo experiment in nursery pigs, subcutaneous pretreatment of rSwIL-4, which was produced from baculovirus expression system, enhanced the severity of respiratory failure with endotoxic shock, and increased the production of TNF-alpha and IL-18 in response to inoculation with LPS. These results indicate that the rSwIL-4 is biologically active in both in vitro and in vivo treatments. Depending on the administration time, pro-inflammatory cytokine productions by IL-4 can cause either inhibitory or stimulatory regulation.

Animals↗
PubMed1988

Uterine-specific proteins in luminal secretions of swine leukocyte antigen-inbred miniature swine with cystic endometrial hyperplasia.

Uterine-specific proteins were evaluated in luminal secretions of Swine Leukocyte Antigen (SLA)-inbred miniature swine with cystic endometrial hyperplasia (CEH) by polyacrylamide gel electrophoresis (PAGE) and Sephacryl S-200 chromatography. CEH and non-CEH (NCEH) pigs (n = 23) were killed on Days 4, 9, and 15 of the estrous cycle (estrus = Day 0) and reproductive tracts were excised for collection of serum and uterine luminal protein. Uterine luminal protein was greater (p less than 0.05) on Day 9 than on Days 4 and 15 (42.9 vs. 6.1 and 29.4 mg, respectively) for CEH pigs and Days 4, 9, and 15 (8.5, 10.1, and 25.6 mg, respectively) for NCEH pigs. The presence of the uterine-specific acidic and basic proteins, as revealed by PAGE, was affected (p less than 0.025) by day of the cycle and CEH condition. All Day 15 NCEH pigs (4 of 4) produced the complete profile of these proteins, whereas none of the uterine protein samples representing other treatment groups contained them. Some minor acidic protein components were present in cystic fluids from CEH pigs, but these fluids lacked the typical uterine-specific proteins. PAGE analysis of Sephacryl S-200 fractions from uterine fluids of Day 15 NCEH pigs revealed the uterine-specific proteins in fractions IV (Mr 40,000) and V (Mr 15,000). The results of the investigation demonstrate an impairment in the secretion of uterine-specific proteins in cyclic SLA miniature swine with cystic endometrial hyperplasia.

Animals↗
PubMed1989

The swine leucocyte antigen (SLA) complex and Sinclair swine cutaneous malignant melanoma.

Cutaneous malignant melanoma of Sinclair swine (SSCM) is an inherited neoplasm present at birth in a majority of affected animals. We have characterized the swine leucocyte antigen (SLA) complex of the Sinclair herd at Texas A & M University using a one-way mixed lymphocyte test and found that one particular haplotype, arbitrarily identified as haplotype B, is associated with the expression of SSCM. Only a single dose of the B haplotype is required for a dominant allele at a 'tumour initiator' locus to be fully penetrant. In addition, swine homozygous for haplotype B develop more primary tumours between birth and weaning than those heterozygous for the B haplotype. Taken together, these findings indicate that tumour initiation, in utero, and expression between birth and weaning may involve different mechanisms.

Animals↗
PubMed2000

Passage of classical swine fever virus in cultured swine kidney cells selects virus variants that bind to heparan sulfate due to a single amino acid change in envelope protein E(rns).

Infection of cells with Classical swine fever virus (CSFV) is mediated by the interaction of envelope glycoprotein E(rns) and E2 with the cell surface. In this report we studied the role of the cell surface glycoaminoglycans (GAGs), chondroitin sulfates A, B, and C (CS-A, -B, and -C), and heparan sulfate (HS) in the initial binding of CSFV strain Brescia to cells. Removal of HS from the surface of swine kidney cells (SK6) by heparinase I treatment almost completely abolished infection of these cells with virus that was extensively passaged in swine kidney cells before it was cloned (clone C1.1.1). Infection with C1.1.1 was inhibited completely by heparin (a GAG chemically related to HS but sulfated to a higher extent) and by dextran sulfate (an artificial highly sulfated polysaccharide), whereas HS and CS-A, -B, and -C were unable to inhibit infection. Bound C1.1.1 virus particles were released from the cell surface by treatment with heparin. Furthermore, C1.1.1 virus particles and CSFV E(rns) purified from insect cells bound to immobilized heparin, whereas purified CSFV E2 did not. These results indicate that initial binding of this virus clone is accomplished by the interaction of E(rns) with cell surface HS. In contrast, infection of SK6 cells with virus clones isolated from the blood of an infected pig and minimally passaged in SK6 cells was not affected by heparinase I treatment of cells and the addition of heparin to the medium. However, after one additional round of amplification in SK6 cells, infection with these virus clones was affected by heparinase I treatment and heparin. Sequence analysis of the E(rns) genes of these virus clones before and after amplification in SK6 cells showed that passage in SK6 cells resulted in a change of an Ser residue to an Arg residue in the C terminus of E(rns) (amino acid 476 in the polyprotein of CSFV). Replacement of the E(rns) gene of an infectious DNA copy of C1.1.1 with the E(rns) genes of these virus variants proved that acquisition of this Arg was sufficient to alter an HS-independent virus to a virus that uses HS as an E(rns) receptor.

Amino Acid Sequence↗
PubMed1985

Passive protection of segmented swine colonic loops against swine dysentery.

Swine-ligated loops were used to demonstrate passive protection against swine dysentery. Loops inoculated with immune sera containing complement and with homologous Treponema hyodysenteriae were normal at necropsy. Loops inoculated with heat-inactivated immune sera and heterologous T hyodysenteriae were not protected. Loops inoculated with heat-inactivated immune sera and homologous T hyodysenteriae were partially protected. Positive control loops inoculated with isolate B204 (88%) or B234 (44%) T hyodysenteriae and normal sera developed lesions typical of swine dysentery, whereas negative control loops inoculated with nonexposed sera only were normal.

Animals↗
PubMedDate not supplied

A highly sensitive and specific gel-based multiplex RT-PCR assay for the simultaneous and differential diagnosis of African swine fever and Classical swine fever in clinical samples.

The development and standardisation of a novel, highly sensitive and specific one-step hot start multiplex RT-PCR assay is presented for the simultaneous and differential diagnosis of African swine fever (ASF) and Classical swine fever (CSF). The method uses two primer sets, each one specific for the corresponding virus, amplifying DNA fragments different in length, allowing a gel-based differential detection of the PCR products. Universal detection of ASF and CSF virus strains was achieved through selection of primers in conserved viral genome regions. The detection range was confirmed by analysis of a large collection of isolates of the two viruses. The high specificity of the assay was proven by testing related viruses, uninfected cell line cultures and healthy pig tissues. Additional confirmatory tests of the ASF and CSF virus amplicon specificity, based on restriction endonuclease analysis with BsmA I or Ban II, respectively, are also described. The analysis of whole blood and serum samples from experimentally infected animals proved the usefulness of the method for an early diagnosis of both diseases, even before the appearance of the first clinical signs. A study of 150 positive field samples from several ASF and CSF outbreaks showed the suitability of this method for a rapid (less than five hours), sensitive and specific differential diagnosis in clinical samples. In addition, a highly sensitive and specific uniplex RT-PCR for CSFV was also developed and standardised as a powerful tool for fast and early diagnosis of the disease.

African Swine Fever↗
PubMed2006

Assignment of 101 genes localized in HSA10 to a swine RH (IMpRH) map to generate a dense human-swine comparative map.

Economically important traits such as growth and backfat in pigs have been shown to be influenced by genes in swine chromosome (SSC) 10q12-->qter corresponding to human chromosome (HSA) 10p. However, since gene information in the swine chromosomal region was limited, we attempted to generate a dense comparative map between SSC10 and HSA10 by mapping the 115 genes of HSA10 to a swine RH map (IMpRH map). In the mapping ten genes were assigned to SSC10, 88 to SSC14, and one to SSC3. One gene was suggested to link to SSC3, and another to SSC9. The correspondences between HSA10 and SSC10 and between HSA10 and SSC14 were essentially consistent with the observations obtained from bi/uni-directional chromosome painting or other results. This study further indicated that a large number of intrachromosomal rearrangements occurred in the synteny-conserved regions following species separation.

Animals↗
PubMed1983

[Populations of harmful rodents on commercial swine-breeding farms and their effect on the technology of swine feeding].

The effect was studied of the swine-feeding technology in five industrial complexes on the population density of the harmful rodents in them. This made it necessary to estimate the population density of the rodents in each productional section of the swine-breeding complexes, and to work out their technologic characteristic on the nutrition principle. It was established that the population density of rodents correlated positively with their access to feeds. In sections where rated, mechanical, and protected feeding was prectised the number of rodents were considerably lower than in sections with unrated feeding of pigs. It is believed that the rat invasion of the buildings in the industrial swine-breeding complexes is a factor that contributes to the rise of populations of harmful rodents, while the vast access to feeds is of greater importance chiefly for their further development.

Animal Feed↗