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Biomedical subjects

J S Guy

Publications and source records attributed to J S Guy.

At least 37 records · Page 2Linked to original sources
PubMed1985

Comparison of the pneumopathogenicity of two strains of bovine viral diarrhea virus.

The pneumopathogenicity in calves of 2 strains of bovine viral diarrhea (BVD) virus, isolate 2724 (a noncytopathogenic virus) and isolate 72 (a cytopathogenic virus), was compared. All calves were inoculated endobronchially, using fiberoptic bronchoscopy. Two calves were given Pasteurella haemolytica, 2 calves were given the noncytopathogenic BVD virus, and 2 calves were given cytopathogenic BVD virus. Five calves were inoculated sequentially with BVD virus and, 5 days later, with P haemolytica. Two of these calves were inoculated with the noncytopathogenic BVD virus and the other 3 with the cytopathogenic strain. Both BVD virus strains caused marked respiratory tract disease in the calves sequentially inoculated with P haemolytica and also impaired pulmonary clearance of P haemolytica. However, the effect of the cytopathogenic strain was more severe than the noncytopathogenic strain, indicating that strains of BVD virus may vary in their pneumopathogenicity for calves.

Animals↗
PubMed1985

Bovine herpesvirus-1 infection of cattle: kinetics of antibody formation after intranasal exposure and abortion induced by the virus.

The kinetics of antibody formation in Holstein heifers after primary and secondary intranasal inoculation of bovine herpesvirus-1 (BHV-1) and after BHV-1-induced abortion was determined. Sera were fractionated by gel filtration and ion-exchange chromatography. The antibody activity within serum immunoglobulin (Ig) isotypes was assessed, using a plaque-reduction neutralization assay. The primary immune response to BHV-1 infection was characterized by the appearance of IgM and IgG antibodies in serum by postinoculation day (PID) 7. Maximal IgG antibody activity occurred at PID 35 in nonpregnant heifers and at PID 14 in pregnant heifers. Thereafter, IgG antibody activity declined slowly in both groups of heifers. Maximal IgM antibody activity occurred at PID 14 in both groups of heifers and declined rapidly thereafter. The IgG antibody activity during primary immune responses was restricted to the IgG1 subclass. Secondary responses were characterized by anamnestic IgG antibody responses. Antibody activity was present within the IgG1 and IgG2 subclasses during secondary immune responses, but the increase in antibody activity during this period was primarily in the IgG2 subclass. Secondary IgM antibody formation was elicited by abortion induced by the intra-amniotic inoculation of BHV-1, but not by reexposure by the intranasal route. Abortion occurred in 1 heifer 28 days after intranasal BHV-1 inoculation. Abortion in this heifer was not associated with a secondary antibody response. The nature of BHV-1 antigenic exposure in the bovine determined the relative distribution of anti-BHV-1 antibody activity in serum IgM, IgG1, and IgG2. The formation of IgM antibody, with the exception of secondary intranasal exposure, indicated recent BHV-1 antigenic exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗
PubMed1985

Kinetics of antibody formation after the reactivation of bovine herpesvirus-1 infection in cattle.

Holstein heifers previously infected with bovine herpesvirus-1 were treated with corticosteroids to reactivate latent infection. The kinetics of serum immunoglobulin (Ig) M, IgG1, and IgG2 antibody formation were determined. The secondary immune response which developed as a consequence of virus reactivation was characterized by an anamnestic IgG antibody response. Secondary IgG1 and IgG2 antibody formation constituted the IgG antibody response. In addition, secondary IgM antibody formation was elicited by this form of bovine herpesvirus-1 antigenic exposure.

Animals↗
PubMed1984

Experimental production of bovine respiratory tract disease with bovine viral diarrhea virus.

Five 6-month-old calves were inoculated with bovine viral diarrhea (BVD) virus (n = 3) or Pasteurella haemolytica (n = 2) endobronchially with a fiberoptic bronchoscope. Five additional calves were inoculated sequentially with BVD virus followed by P haemolytica at a 5-day interval. Blood samples were collected daily from the calves for bacterial isolation. Clinical signs of respiratory tract disease in calves were recorded daily. If the calves survived, they were killed for necropsy 3 or 4 days after inoculation with P haemolytica (or 8 days after inoculation with BVD virus). The extent and nature of pulmonary lesions in the calves were determined, and the lower portion of the respiratory tract (lungs and trachea) was examined for both these organisms. The 3 calves, inoculated with BVD virus only, developed mild clinical signs mainly manifested as fever, nasal discharge, and occasional cough. Approximately 2% to 7% of the total lung capacity of these calves was pneumonic. Mild clinical signs and localized lesions involving about 15% of the lung volume developed in the 2 calves exposed to P haemolytica only. However, severe fibrinopurulent bronchopneumonia and pleuritis involving 40% to 75% of lung volume developed in the 5 calves inoculated sequentially with BVD virus and P haemolytica. The possible role BVD virus may have in bovine respiratory tract disease is discussed.

Animals↗
PubMed1984

Use of fiberoptic bronchoscopy in experimental production of bovine respiratory tract disease.

Fourteen 6-month-old calves were infected with Pasteurella haemolytica or infectious bovine rhinotracheitis (IBR) virus. Four calves were inoculated sequentially with IBR virus followed by P haemolytica at a 5-day interval. Calves were inoculated by allowing them to inhale an aerosol of the organism or by placing an inoculum in the right lung, using fiberoptic bronchoscopy. Clinical signs of infection were recorded, and the calves, if they survived, were killed and necropsied 3 days after inoculation with P haemolytica (or 8 days after inoculation with IBR virus). The extent of pulmonary lesions was determined, and the lower respiratory tract (lungs and lower trachea) was examined for both organisms. Inoculation of the calves by aerosolization with IBR virus alone resulted in mild respiratory tract disease. Mild-to-moderately severe respiratory tract disease developed as a result of sequential inoculations by aerosolization with IBR virus and P haemolytica. However, respiratory tract disease did not develop in calves exposed by aerosol to P haemolytica alone. Large numbers of these organisms were recovered from the lower respiratory tract of the dually inoculated calves, only indicating delayed pulmonary clearance. Mild clinical signs of disease but substantial, though localized, pneumonic lesions developed in calves inoculated with P haemolytica by fiberoptic bronchoscopy. Calves inoculated with IBR virus by the latter procedure developed moderately severe respiratory tract disease involving 25% to 30% of the total lung volume. Lesions occurred mainly in the right lung, but the left lung also had marked lesions in these calves.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1980

Genome of porcine transmissible gastroenteritis virus.

The Purdue strain of transmissible gastroenteritis virus, a porcine coronavirus, was grown to titers of greater than 10(8) PFU/ml in a swine testicle cell line, and the RNA was isotopically labeled with [3H]uridine. The RNA was extracted from purified virus and was found to have the following properties. (i) It consisted primarily of a homogeneous large-molecular-weight species which electrophoretically migrated with an apparent molecular weight of 6.8 X 10(6) under denaturing conditions. (ii) It migrated electrophoretically at the same rate on nondenaturing gels before and after heat denaturation, suggesting that it does not consist of subunits. (iii) It was susceptible to pancreatic RNase A digestion in high (0.3 M) NaCl. (iv) It was polyadenylated to the extent that greater than 60% of the native RNA bound to oligodeoxythymidilic acid-cellulose under conditions of high (0.5 M) NaCl. RNA extracted from virions was infectious. This coronavirus can therefore be characterized as a positive-strand RNA virus.

Animals↗
PubMed1979

Bovine coronavirus genome.

The tissue culture-adapted strain (Mebus) of the bovine coronavirus was grown to titers of greater than 10(7) 50% tissue culture infective doses per ml in secondary bovine embryo kidney cells, and the RNA was isotopically labeled with [3H]uridine. The RNA was extracted from purified virus and was found to have the following properties. (i) It consisted primarily of a homogeneous large-molecular-weight species which comigrated electrophoretically with vesicular stomatitis viral RNA and therefore had an apparent molecular weight of 3.8 X 10(6). (ii) It remained as a 3.8 x 10(6)-molecular-weight molecule after heat denaturation when rapidly harvested virus was examined. (iii) It was 80% susceptible to pancreatic RNase A digestion in high (0.3 M) NaCl, and the 20% resistant fraction was 4S to 7S in size. (iv) It was polyadenylated to the extent that 40 and 60% of the native RNA bound to polyuridylic acid-Sepharose and oligodeoxythymidylic acid-cellulose, respectively, under conditions of high (0.5 M) NaCl.

Animals↗