Swine Strains Research Articles

Isolation of ortho- and paramyxoviruses from migrating feral ducks in Hokkaido. Brief Report.

A total of 18 hemagglutinating agents were isolated from 14 of 278 migrating feral ducks In Hokkaido during the surveillance studies conducted from 1978 to 1981. Seven of the 18 isolates belonged to paramyxovirus and the rest to influenza A virus. Five isolates of paramyxovirus reacted specifically with antiserum to duck/HK/199/77 and 7 isolates of influenza A virus possessed the antigenic configuration of H10N3. Three of the isolates possessed an hemagglutinin that has no antigenic relation to any of the 26 known strains of avian, swine, equine and human influenza A viruses.

Correlates of ovarian morphology, estrous behavior, and cyclicity in an inbred strain of miniature swine.

Ovarian morphology and behavioral relationships were studied in a group of nine miniature pigs with a characteristically small litter size (-5) and an average coefficient of inbreeding of 0.39. The first day of standing estrus was designed as day 0, Laparoscopy was used to evaluate and photograph ovarian activity on days 1, 5, 11, 17, and day 2 of the subsequent estrous cycle. Mean (+/-SEM) duration of estrus and the estrous cycle was 3.1 +/- 0.2 and 22.6 +/- 0.3 days, respectively. An average of 9.0 +/- 0.4 vesicular follicles developed/estrous period and 96% of the follicles showed morphologic evidence of ovulation resulting in a mean of 8.6 +/- 0.3 corpora lutea (CL) per animal. There was no significant correlation between the degree of inbreeding and number of vesicular follicles (r = 0.27) or CL (r = 0.28) developing/cycle within the experimental group. Mature preovulatory follicle and CL size ranged from 6-12 mm and 8-12 mm in diameter, respectively, and 22.5% of the newly formed CL contained distinct postovulatory stigmata. These data indicated that 1) temporal relationships of sexual behavior and gross ovarian morphology in the miniature pig were similar to descriptions previously reported for the standard pig, and 2) the reduced litter sized characteristic to this particular strain is, at least in part, due to decreased number of vesicular follicles developing during the estrous cycle.

Immunological Cross Reactions of Antigens of Erysipelothrix Rhusiopathiae and Heart Tissue From Swine

Antisera against 4 strains of E. rhusiopathiae and against heart tissues from swine were raised in rabbits and used in gel double diffusion precipitation tests against 10 strains of E. rhusiopathiae of various origins and against heart tissues. Precipitation lines showing cross reactions were found in tests with one bacterial antiserum and with both tissue antisera tested. This indicates a similarity between the antigenic determinants of heart muscle and valves from swine and certain strains of E. rhusiopathiae. The possible relationship between the results and the virulence of the microorganisms is discussed.

Serological relation between calf diarrhea coronavirus and hemagglutinating encephalomyelitis virus.

SummaryNeutralizing (NT) and hemagglutination-inhibiting (HI) antibodies to calf diarrhea coronavirus (CDCV) and hemagglutinating encephalomyelitis virus of swine (HEV) (strain 67 N) were detected in high proportions of normal adult cattle and pigs in Japan. Since comparison of NT and HI titers in the serum samples suggested an antigenic difference between the viruses, cross NT and HI tests of these viruses were carried out with antisera raised in rabbits. The homologous NT titers were markedly higher than the heterologous titers. In HI tests essentially the same results were obtained. These findings indicate the presence of a marked difference in antigenic make-up between CDCV and HEV. NT and HI tests can clearly differentiate the viruses, although there is some cross reaction.

Incidence des infections a virus grippal chez le porc (1977–1979). Enquete serologique dans des troupeaux de reproducteurs

A serological survey by HI and HR tests was performed on specimens representative of the porcine production in Brittany (France). The influenza infection reached 1 3 of the breedings in 1977, 80% in 1978 and 60% in 1979. The percentage of infected animals was respectively 13,5% in 1977, 50% in 1978 and 36,5% in 1979. The influenza infection was evaluated according to the age of the animals, the specificity of the antibodies. Results were as follows: —A/PC/73 related viruses spread before 1975. —A/PC/73—A/Vic/75 related viruses spread in the winter 1975–1976, then in the winter 1977–1978, A/Tex/77 related strains also reached the breedings. —few animals (less than 10%) carried anti H1N1 RH antibodies as soon as March 1978. No HI antibody against swine strains were detected. Starting in May 1978, anti A/NJ/76 antibodies were detected by RH in 7 out of 25 breedings.

Activity of Amantadine, Rimantadine, and Ribavirin Against Swine Influenza in Mice and Squirrel Monkeys

Amantadine, rimantadine, and ribavirin given orally, either prophylactically or therapeutically, reduced mortality and increased the survival time of 3-week-old mice infected with the type A/New Jersey/8/76 (swine) strain of influenza virus. In addition, amantadine and rimantadine, administered therapeutically, increased the rate of virus clearance from lungs of infected mice. Administration of amantadine either before or after virus challenge ameliorated the illness in squirrel monkeys; when administered therapeutically, it appeared to eliminate virus shedding from infected monkeys within hours after therapy was initiated.

Transplantation in miniature swine. I. Fixation of the major histocompatibility complex.

Three strains of miniature swine, each homozygous for a different allele of the major histocompatibility locus (MHC), have been developed by a selective breeding scheme based on tissue typing of the offspring of each generation. Prior to breeding, the original parents were reciprocally immunized by skin grafts and lymphocyte injections to produce lymphocytotoxic antisera. These antisera were then used to assess the MHC genotype of the offspring by an analysis based on selective absorption of cytotoxicity. Offspring inheriting the same serologically determined genotype were then bred sequentially. Subsequent mixed lymphocyte cultures showed a pattern of reactivity consistent with the serological genotyping, further confirming the homology between the MHC of these miniature swine and those of man and mouse. In addition to their usefulness as a model for large animal surgical transplantation, these animals provide an abundant homozygous source of histocompatibility antigens and of antihistocompatibility antisera for use in chemical characterization of products of the MHC.

Influenza virus antigen in postencephalitic parkinsonism brain. Detection by immunofluorescence.

Brains of six patients with postencephalitic parkinsonism were examined for influenza virus antigen by direct immunofluorescence. Tissue sections were exposed to fluorescein-conjugated globulin directed against the NWS, WSN, WS, and PR8 strains of influenza A 0 , the ribonucleoprotein of the WSN strain, the swine strain of influenza A, the Japan strain of influenza A 2 , the Lee strain of influenza B, measles, and herpes simplex virus. Intranuclear fluorescent antigen was detected in hypothalamic and midbrain sections prepared from all six cases after staining with antibody to the two neurotropic influenza A 0 strains (NWS and WSN) and to the ribonucleoprotein of the WSN strain. No fluorescence was observed after staining of similar sections prepared from the brains of five patients with idiopathic Parkinson disease with labeled influenza NSW antiserum.

Specific and nonspecific cell-mediated resistance to influenza virus in mice.

We found that influenza virus had the capacity to replicate in the peritoneal macrophages of normal mice, as revealed by the development of hemadsorption and the appearance intracellularly of S and V antigens. Cell-mediated resistance was studied in mice infected with influenza virus or a bacterial sytem of induction-elicitation. In the homologous system, mice were injected intraperitoneally or exposed by aerosol to a sublethal dose of an egg-adapted swine strain of influenza virus. In the heterologous system, they were infected repeatedly with Staphylococcus aureus and elicited by subcutaneous or aerosol administration of staphylococcal antigens. The peritoneal macrophages from mice specifically or nonspecifically immunized were significantly more resistant than those from normal mice. Also longer survival to in vivo challenge by the mouse-adapted virus, as compared with normal mice, was indicated in bacterially stimulated mice.

Influence of adrenergic blockage upon some endocrine and metabolic parameters in a stress-susceptible and a fat strain of swine.

Influence of adrenergic blockage upon some endocrine and metabolic parameters in a stress-susceptible and a fat strain of swine.

Melanoma in Sinclair Swine: A New Animal Model

A new animal model for the study of melanocytic tumors is presented. A strain of miniature swine, bred for small size, has genetically determined tumors similar to many types of human pigment tumors, from benign junctional nevi to bizarre metastatic melanomas. Some tumors regress spontaneously and this regression may be accompanied by a generalized depigmentation of the animal with a predilection for many of the same anatomic areas involved in human vitiligo. These animals are ideal for study of the interrelationships of senescence, actinic exposure, and other factors in malignant degeneration, as well as the role of immunity and growth control factors in regression and regulation of tumor growth.

Wall teichoic acids in animal Staphylococcus aureus strains determined by precipitation.

567 strains of Staphylococcus aureus isolated from a number of animal hosts were examined by agar gel precipitation for wall teichoic acids or other wall polysaccharides. The species was shown to be heterogeneous with regard to these constituents. Three groups could be distinguished: 1. The strains which had been classified biochemically as belonging to the human, bovine, hare and horse biotypes, and some of the swine strains, contained polysaccharide A. Of these, the horse strains contained polysaccharide Aα whereas the other strains regularly contained polysaccharide Aß. Of the latter, a higher incidence of additional polysaccharide Aα distinguished the human biotype from other biotypes. 2. The dog strains contained none of the reference polysaccharides but an unknown polysaccharide (P). 3. The pigeon and mink strains contained polysaccharide C. The occurrence of polysaccharide C in the biochemically least active biotypes is interesting, indicating a bridge towards the polysaccharide AßC group of S. epidermidis.

Differences in the response of rabbit small intestine to heat-labile and heat-stable enterotoxins of Escherichia coli.

The response of adult rabbit small intestine to the heat-stable (ST) and heat-labile (LT) enterotoxins of Escherichia coli has been investigated by employing the ligated loop technique. Fluid accumulation was determined in relation to enterotoxin dose and duration of gut exposure. The individual responses to ST and LT differed in a characteristic manner. Onset of net fluid accumulation in response to ST appeared to be immediate even at the lowest dose tested. Onset of net fluid accumulation in response to LT was rapid at high doses but delayed at low doses. Maximum volume per length ratios elicited by ST occurred between 4 and 6 h after injection of loops over the entire range of doses tested. However, maximum ratios elicited by LT occurred no less than 10 h after injection even at low doses. Fluid accumulation elicited by LT increased in duration with increasing dose; high doses of LT producing a response which was sustained for at least 18 h. The net effect of these differences in reaction characteristics is a sharp increase in the proportion of the cumulative net secretory response attributable to LT with time. Therefore, a 6-h assay time is appropriate for the titration of ST, whereas an 18-h assay is not. The 18-h assay was found more appropriate for toxin-antitoxin neutralization studies since only LT was neutralized by anti-enterotoxin serum. LT of E. coli (swine) strain P-263 and (human) strain 334 was neutralized by antibody stimulated by enterotoxin from E. coli (human) strain H-10407. LT was labile to mild acid conditions, whereas ST was not.

Proposal for Standardization of the Designations Used for Serotypes of Erysipelothrix rhusiopathiae (Migula) Buchanan

A serological investigation of 45 swine erysipelas strains showed that among Erysipelothrix rhusiopathiae strains of different origin there are some with the same serotype designation that differ serologically, and there are others which have different serotype designations but which belong to the same serotype. To put an end to the resultant confusion, it is necessary to use both a uniform serological method (the double agar-gel diffusion precipitation test which employs autoclaved antigen and type-specific sera seems to be the most suitable) and a uniform system for designating the serotypes. It is proposed that Arabic numerals instead of letters be applied to serotypes of E. rhusiopathiae according to the chronological order in which the serotypes are described. Strains belonging to one serotype but differing in their antigenic structure can be differentiated by small letters placed after the numerals. The letter N is used to designate swine erysipelas strains which do not have a type-specific antigen.

Inactivation of the hemagglutinins of type A influenza viruses by physical and chemical means: an aid to classification.

The effects of temperature and treatment with sodium dodecyl sulfate, Tween 20, dithiothreitol, trypsin, or guanidine on the hemagglutinating capacity of six strains of type A influenza virus (A(0)/PR8/34, A(1)/CAME/46, A(2)/J305/57, A(2)/Bethesda/63, A(2)/HK/Aichi/68, and A(2)/HK/80/68), one strain of swine virus (A/Swine/76/?), and one equine strain (A/Equi-2/63) were determined. The two Hong Kong strains could be readily distinguished from the earlier A(2) strains by the resistance of their hemagglutinins to trypsin treatment and their inability to recover hemagglutinating capacity after removal of dithiothreitol from treated virus preparations. In these respects, the equine strain most closely resembled the Hong Kong variants. The pattern of hemagglutination inactivation also set the swine, PR8, and CAME strains apart from each other as well as from the other five strains. The results suggest that separation of type A viruses into groups by the pattern of inactivation of their hemagglutinins may be a valuable adjunct to standard serology for a more definite classification of these viruses.

The chemical reactions of the haemagglutinins and neuraminidases of different strains of influenza viruses: III. Effects of proteolytic enzymes

The action of trypsin and pronase on the haemagglutinins and neuraminidases of eight strains of influenza virus has been examined.The haemagglutinins of all the strains were highly susceptible to digestion by pronase but there were great variations in resistance to trypsin.The neuraminidases of the eight strains were of three types. The neuraminidases of the A 1 strains and the DSP strain of virus A were highly susceptible to destruction by both enzymes. The neuraminidases of the PR 8 and Swine strains showed partial resistance especially to trypsin, while the A 2 strains and the LEE strains of virus B possessed neuraminidases that were completely resistant to both trypsin and pronase.Proteolytic enzymes released free neuraminidases from the A 2 and LEE viruses the morphology of which was different from that of neuraminidases released by detergent treatment.

Division of mycoplasmas into subgroups.

SUMMARY: The deoxyribonucleic acid (DNA) base compositions of 12 recently isolated or new species of mycoplasmas fell within the range known for the Mycoplasma group. By DNA-DNA hybridization a new sterol-nonrequiring strain, s-743, was unrelated to Mycoplasma laidlawii or M. granularum, the latter two strains showing moderate cross-reactivity; swine strain B3 appeared to be related to M. mycoides var. capri. From these results and information in the literature, the mycoplasmas have been divided into six provisional subgroups on the basis of physiological characters, DNA base composition and nucleic acid hybridization. Some speculations are made on the significance of heterogeneity among mycoplasmas.

The chemical reactions of the haemagglutinins and neuraminidases of different strains of influenza viruses. II. Effects of reagents modifying the higher order structure of the protein molecule.

SUMMARYThe results of treatment of influenza virus strains with chemical reagents acting on the higher-order structure of protein molecules shows that both the haemagglutinating and enzymic activities are susceptible to these agents but there are considerable differences between the different strains and the neuraminidase activity is more sensitive than the haemagglutinating activity.The neuraminidase activity of A and A1strains is destroyed by urea, guanidine, urea+dithiothreitol and mercuric chloride. The haemagglutinin of the PR 8 and SWINE strains is resistant to urea and mercuric chloride but destroyed by guanidine and by urea+dithiothreitol. The haemagglutinin of the DSP strain of virus A and the A1strains is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.The neuraminidase activity of the A2strains is more resistant than that of the A and A1strains. It is resistant to mercuric chloride and partially resistant to urea but is destroyed by guanidine and by urea+dithiothreitol. The A2haemagglutinin is resistant to urea, urea+dithiothreitol, and mercuric chloride but is destroyed by guanidine.The LEE virus neuraminidase is resistant to urea and partially resistant to guanidine but is destroyed by urea+dithiothreitol and mercuric chloride. The LEE haemagglutinin is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.It is suggested that the surface projections of the virus particle are protein polymers each made up of three or four monomers which are the components of the V antigen complex. Antigenic activity is a function of the primary or secondary structure of the monomers, haemagglutinin activity is a function of the tertiary structure of the monomers, while neuraminidase activity is a function of the quaternary structure of the polymer.From studies of the chemical reactions of their haemagglutinins and neuraminidases strains of influenza virus A can be classified into groups. These groups are very similar to but not precisely identical with groupings made by serological methods.

Selection of antigenic mutants of influenza viruses. Isolation and peptide mapping of their hemagglutinating proteins

Antigenic mutants of the swine and BEL strains of influenza A virus were isolated after serial passage of these viruses in the presence of sublimiting concentrations of homologous antibody of low avidity. Antisera to wild-type swine and BEL viruses reacted in antihemagglutinin and neutralization tests to lower titers with the mutants than with the wild type viruses, thus imitating the phenomenon of “antigenic drift” which occurs among influenza viruses in nature. The hemagglutinating proteins from the wild-type and mutant viruses were isolated and digested with trypsin, and the diffusible tryptic peptides were mapped. The peptide map from wild-type swine virus was similar to that from the swine mutant P12, with a single clear-cut exception; a peptide present on the wild-type map was absent from the map of the mutant. Differences were also seen between the peptide maps from wild-type BEL virus and its antigenic mutants. This suggests that antigenic variation among influenza viruses is related to changes in the amino acid sequence of their antigenic proteins. It is not yet known whether the changes occurred in the antigenic determinants of the viral proteins, or in some other region of the molecule.

Relative Antigenic Potency in Man of Polyvalent Influenza Virus Vaccines Containing Isolated Hemaggi Utinins or Intact Viruses

Summary The antibody responses of military recruits to vaccination with aqueous or mineral oil adjuvant polyvalent vaccines containing either purified hemagglutinins or intact viruses were compared. The yield of HI antibodies was generally higher after vaccination with purified hemagglutinins derived from swine, A, A1 and A2 strains than after vaccination with the corresponding intact viruses. The yield of HI antibodies after vaccination with hemagglutinins obtained from prototype strains of influenza B was always at least equal to that observed after use of intact virus vaccines, and sometimes higher. The significance of these findings is discussed.