Serological property and replication in cell cultures of porcine reproductive and respiratory syndrome viruses isolated in Japan.

The serological property and replication in swine alveolar macrophages (SAM) and MARC-145 cell cultures of 35 porcine reproductive and respiratory syndrome (PRRS) viruses isolated in SAM were investigated. All the isolates were reacted almost equally with antisera against three Japanese isolates including EDRD-1 strain (American type) in immunoperoxidase monolayer assay (IPMA), but weakly or did not react with antiserum against Lelystad virus (European type) indicating that the Japanese isolates are more closely related to an American type virus. Twenty two of 35 isolates replicated with CPE both in SAM and MARC-145 cells, whereas remaining 13 isolates did not show CPE in MARC-145 cells.

Phagocytosis of splenetic neutrophils of mice enhanced by orally administered peptidoglycan from Bifidobacterium thermophilum.

A preparation of peptidoglycan (PG) of swine Bifidobacterium thermophilum was orally administered to SPF-BALB/C and ICR mice and its effect on phagocytosis splenetic neutrophils from PG administered mice was measured by chemiluminescent response (CL) and fluorometric analysis and the result was compared with that of non-treated mice. PG stimulated phagocytosis of neutrophils in a dose-dependent manner, whereas dosage exceeding the optimum concentration (500 microgram) inhibited phagocytosis. The maximum effect on phagocytosis of neutrophils was observed at 3 days after administration of PG 500 microgram.

Oligonucleotide probes for Bordetella bronchiseptica based on 16S ribosomal RNA sequences.

Bordetella bronchiseptica 16S ribosomal RNA (rRNA) gene was cloned and identified. On the basis of information from computer-assisted sequence comparison of the B. bronchiseptica 16S RRNA sequences with that of other bacterial species, we constructed B.

Detection of interleukin-6 and prostaglandin E2 in bronchoalveolar lavage fluids of pigs experimentally infected with Mycoplasma hyponeumoniae.

In this study, interleukin-6 (IL-6) and prostaglandin E2 (PGE2) were detected in the bronchoalveolar lavage fluids (BALF) from pigs experimentally infected with Mycoplasma hyopneumoniae. IL-6 was detected at 2 weeks post-inoculation (PI), and significantly increased levels of PGE2 were observed at 4 weeks PI. In the BALF collected from infected pigs at 4 weeks PI, the levels of IL-6 increased significantly in the pigs with pneumonic lesions.

Enhancement of cytotoxic activity of lymphocytes in mice by oral administration of peptidoglycan (PG) derived from Bifidobacterium thermophilum.

A preparation of peptidoglycan (PG) of Bifidobacterium thermophilum (B. thermophilum) of swine was orally administered to SPF-C57BL/6CrSlc mice in order to confirm the enhancement of the cytotoxic activity of natural killer cells (NK), intraperitoneal cytotoxic T lymphocytes (CTL) and lymphocytes stimulated by concanavalin A (Con A-stimulated lymphocytes). The NK cells from the spleen and the mesenteric lymph node (MLN) of mice that were continuously fed with PG-mixed feed for three weeks showed a significantly higher rate of cytolysis than those from the control group.

Replication of virulent and attenuated strains of Aujeszky's disease virus in swine alveolar macrophages.

In vitro and in vivo replication of Aujeszky's disease virus (ADV) in swine alveolar macrophages (AM) was studied using two virulent strains and a vaccine strain with deletions in the thymidine kinase and gIII genes. In vitro, AM were highly permissive to virulent ADV infection. Virus progeny titers of virulent strains in the cell phase and in the fluid phase were higher than 10(7.

Enhanced resistance of mice to Escherichia coli infection induced by administration of peptidoglycan derived from Bifidobacterium thermophilum.

Peptidoglycan (PG) of Bifidobacterium thermophilum (B. thermophilum) from swine were orally administered to SPF-ICR mice in order to confirm the enhancement of the defence activity of the mice against Escherichia coli (E. coli) infection.

Increased levels of tumor necrosis factor and interleukin 1 in bronchoalveolar lavage fluids from pigs infected with Mycoplasma hyopneumoniae.

We examined the levels of tumor necrosis factor (TNF)-alpha and interleukin-1 (IL-1) in bronchoalveolar lavage fluids (BALF) from pigs experimentally infected with Mycoplasma hyopneumoniae using biological assays with WEHI-164 cells and D10.G4.1 cells, respectively.

Distinction between Aujeszky's disease virus-infected and vaccinated pigs by hemagglutination-inhibition test.

A hemagglutination-inhibition (HI) test was applied to distinguish virulent Aujeszky's disease virus infected pigs from those immunized with a glycoprotein gIII deletion vaccine. The vaccine strain, dlg92/dltk, did not have hemagglutination activity with mouse erythrocytes and the pigs vaccinated five times with the dlg92/dltk strain failed to develop HI antibody, although they developed neutralizing antibody with 128 to 512 titers to Aujeszky's disease virus. On the other hand, these pigs produced HI antibody 1 to 2 weeks after virulent virus inoculation.

Experimental pneumonia of pigs infected with Aujeszky's disease virus and Actinobacillus pleuropneumoniae.

Experimental infections were induced out to examine whether Aujeszky's disease virus (ADV) infection in pigs results in a severe pneumonia by Actinobacillus pleuropneumoniae. Intranasal inoculation of ADV (10(6.9) median tissue culture infective dose/head) in 4-month-old primary specific-pathogen-free pigs was followed by the inoculation of A.

A serological survey of encephalomyocarditis virus infection in pigs in Japan.

A total of 1502 pig sera collected between 1990 and 1991 at 65 farms in 22 prefectures were subjected to neutralization test to encephalomyocarditis (EMC) virus. Of them, three hundred eighty seven pigs (25.8%) from the 55 farms (84.

Multiplication and immunogenicity of a temperature-sensitive and thymidine kinase-deficient strain of Aujeszky's disease virus in pigs.

Hysterectomy-produced colostrum-deprived 5- and 27-day-old pigs were inoculated intramuscularly (IM) or intranasally (IN) with the temperature-sensitive and thymidine kinase-deficient ZHtsTK- strain of Aujeszky's disease virus (ADV), and the nasal swabs and organs of the pigs were periodically collected for virus isolation. No abnormal clinical signs were observed in these pigs, except for a mild febrile response. Viral shedding in the nasal swabs with low titers was detected in the pigs inoculated IN between postinoculation day (PID) 1 and 5, but not in those of the pigs inoculated IM.

Toxigenic type A Pasteurella multocida as a causative agent of nasal turbinate atrophy in swine.

Although no clinical signs of atrophic rhinitis (AR) were recognized in 2- and 5-week-old pigs, approximately 60% of 2- to 6-month-old pigs showed clinical signs of AR in an affected pig farm. None of the pigs had normal turbinate at slaughter. Bordetella bronchiseptica was not isolated from any of the pigs before onset and incipient stage of the outbreak (2-week to 2-month-old).

Experimental atrophic rhinitis in 2 and 4 month old pigs infected sequentially with Bordetella bronchiseptica and toxigenic type D Pasteurella multocida.

Experimental infections with Bordetella bronchiseptica and/or toxigenic type D Pasteurella multocida were studied in 2- and 4-month-old primary specific-pathogen-free pigs. None of the 2-month-old pigs inoculated with B. bronchiseptica or P.

Characterization of Japanese isolates of Aujeszky's disease virus by restriction endonuclease cleavage patterns, virulence in mice and thymidine kinase activity.

Twenty four cloned isolates of Aujeszky's disease virus collected from outbreaks of Aujeszky's disease from 1981 through 1989 in Japan were characterized by their restriction endonuclease (RE) cleavage patterns, virulence for mice and thymidine kinase (TK) activity. All of the isolates belonged to Type II of the four types classified by Herrmann et al. (1984).

Avirulent ts and thymidine kinase-deficient mutant of Aujeszky's disease virus.

The temperature-sensitive (ts), thymidine kinase-deficient (TK-) mutant designated ZHtsTK- strain, of Aujeszky's disease virus (ADV) was isolated from a virulent strain with the treatments using 5-bromodeoxyuridine and arabinosylthymine. The ZHtsTK- strain was easily distinguished from the other virulent ADV strains by plaque size on HmLu-1 and chicken embryo fibroblast cells and by restriction endonuclease analyses using Bam HI, Sal I and Kpn I. The ZHtsTK- strain was avirulent for mice, guinea pigs and rabbits, and produced neutralizing antibodies to ADV in these animals.

Isolation of Getah virus from dead fetuses extracted from a naturally infected sow in Japan.

Three viruses producing a cytopathic effect in cell culture were isolated from dead fetuses extracted from a naturally infected sow, and were found to be serologically identical by neutralization tests. One of the viruses was cloned and named the Sakura strain. The Sakura strain was identified as Getah virus by cross-neutralization tests.

Drug resistance and R plasmids in Pasteurella multocida isolates from swine.

A total of 163 strains of Pasteurella multocida isolated from swine were examined for drug resistance and R plasmids. Strains resistant to sulfadimethoxine (Sar), ampicillin (Apr), streptomycin (Smr), kanamycin (Kmr), and chloramphenicol (Cpr) were found in 93.9, 1.

Linkage of K99 production and STa activity in a plasmid of an Escherichia coli porcine isolate.

An Escherichia coli strain ZP118 of porcine origin was shown to harbor a 68-megadalton (Md) plasmid coding for a colonization factor K99 and heat-stable enterotoxin (STa), and a self-transmissible 51-Md plasmid coding for drug resistance. One of the transconjugants obtained by mating between ZP118 and E. coli C was found to harbor a 90-Md plasmid coding for K99, STa and drug resistance.

Incidence and some characteristics of fimbriae FY and 31A of Escherichia coli isolates from calves with diarrhea in Japan.

Escherichia coli isolates from calves with diarrhea (1 day to 8 weeks old, 140 individuals) were surveyed for the three immunologically distinct fimbrial adhesins FY, 31A, and K99. Of a total of 1,370 strains isolated, 96 (7.0%), 34 (2.