Biomedical subjects

G K Georgiev

Publications and source records attributed to G K Georgiev.

9 recordsLinked to original sources

PubMed1987

[Rotavirus enteritis in buffaloes].

Immunodiffusion was used to investigate a total of 492 serum samples of buffaloes--buffalo calves up to the age of 6 months and buffalo heifers--on both private and public farms. Positive serological reagents for rotaviruses were established in 73.4 per cent of the cases. The study of the same samples via the blocking ELISA test revealed the presence of 86.2 per cent positive cases. It was demonstrated that this type of the ELISA technique was a more precise method for the demonstration of group specific rotavirus antibodies in buffaloes. The results obtained spoke of the widely occurring rotavirus infections among the buffalo populations in this country. Particularly intense was the circulation of rotaviruses in buffalo calves aged up to six months. The study of 46 fecal samples from buffalo calves with diarrhea by means of the immunodiffusion and ELISA tests revealed that in as many as seven of them there were rotaviruses. This unquestionably demonstrated the participation of these agents in the etiology of enteritis in buffaloes.

Animals↗

PubMed1987

[Electron microscopy research on cytopathic rotaviruses in cell cultures].

Studied was the virus reproduction in cell cultures of MA-104 of the referent rotavirus strain Lincoln, and of the isolated from calves rotavirus Trebich 248/82 and Dolno-sakhrane 39/82. Observed were the following main morphologic structures: electron-dense oval fractions, fractions of with single and double membrane, fractions with supercapsular membrane and electronic-densely granulated zones--viroplasms. There were not established considerable differences between the referent and the isolated from calves rotavirus strains in our country.

Animals↗

PubMed1986

[Attenuated vaccine against rota- and coronavirus enteritis in calves].

Tested was the effect of the Bulgarian attenuated vaccine of rota- and corona-viruses 'PoKo-81', via treatment of dry and freshly calved cows (injected into the udder) and newborn calves (peritoneal injection). It was found that calves fed three times daily on milk obtained from cows that had had intramammary injections did not develop clinical signs of a disease following experimental infection with rota- and corona-viruses. When the cows on infected farms were treated in the same way the disease in calves, offered immune milk, dropped to 36 per cent as against calves of unvaccinated cows, with which morbidity ran as high as 85 per cent. Calves vaccinated via the peritoneum did not fall ill after infection with rota- and corona-viruses on the 6th day following vaccination. In experiments on 18 infected farms morbidity among control, unvaccinated calves was 76 per cent, and mortality--6.8 per cent. With vaccinated calves on the same farms morbidity dropped to 44 per cent, and mortality--to 2.5 per cent. The duration of diarrhea in the vaccinated calves was radically lowered. Discussed is the possibility to enhance the protective effect of the vaccine.

Animals↗

PubMed1986

[Enhanced luminescence intensity in immunofluorescent preparations following trypsin treatment].

Comparative investigations were carried out on the immunofluorescent preparations of cell cultures infected with bovine viruses--rota-, corona-, respiratory-syncytial, parainfluenza-3, adeno-1, and herpes-1--to test various fixatives and the effect of trypsin in raising the sensitivity of the immunofluorescence method. The effect of trypsin was manifested in fixation with formalin, ethanol, methanol, and acetone treated immunofluorescent preparations of cell cultures infected with rota- and adeno-viruses as well as in fixation with acetone of cultures infected with respiratory syncytial virus, parainfluenza-3 virus, and corona virus. Formalin, ethanol, and partly methanol were shown to be unsuitable for the purpose of fixation of cell culture preparations infected with viruses that contained a lipoprotein envelope. It was found that the treatment of immunofluorescent preparations with trypsin following fixation and prior to their treatment with conjugated antisera enhanced considerably the number of fluorescent cells and the intensity of fluorescence itself provided 0.1 per cent trypsin was used for 5 to 10 min at 37 degrees C--for cell culture preparations, and 0.1 per cent trypsin was used for 20 to 30 min at 37 degrees C--for paraffin sections of acetone-fixed tissues.

Animals↗

PubMed1985

[Serotyping of cytopathic rotavirus strains isolated from calves].

Antistrain sera were obtained against cytopathic rotavirus strains isolated from calves as well as against reference rotavirus strains, belonging to I and II serotype of the bovine rotaviruses with which cross antigenic studies were carried out. It was found that the isolated DS 39/82 and TR 248/82 strains belonged to I serotype of the bovine rotaviruses. Data was obtained speaking of some minor antigenic differences between strain TR 248/82 and strain DS 39/82 as well as between strain TR 248/82 and the reference rotavirus strain Lincoln (I serotype), which showed that there existed serologic variants between the strains of this serotype.

Animals↗

PubMed1984

[Virological and bacteriological research on the etiology of gastroenteritis in newborn calves].

Virologic and bacteriologic studies were carried out of samples taken from calves with clinical gastroenteritis and from calves that died at the age of 2 to 10 days. A total of 199 samples were investigated of calves on 48 cattle-breeding farms. In 69 of the cases (34.2 per cent) strains of Escherichia coli were isolated, prevailing being those of the O8, O9, O15, O21, O26, O55, and O78 serogroups. Three of the strains isolated from fecal samples of clinically affected calves possessed the K99 antigen. The indirect immunosorbent method was employed, with 113 samples (56.8 per cent) identifying rotaviruses, and via the indirect immunofluorescence method in 26.6 per cent of the post mortem samples the virus of the mucosal disease was identified. On individual farms with records of the disease most often mixed infections of E. coli and rotaviruses were found. In order to organize effective prophylaxis and control complex bacteriologic and virologic investigations should be carried out with higher number of clinical and post mortem samples.

Animals↗

PubMed1984

[Experiments to isolate cytopathic strains of bovine rotaviruses].

Experiments were carried out to isolate cytopathic strains of bovine rotaviruses. Material from a total of 129 positive fecal samples, taken from calves affected with rotavirus gastroenteritis, was used to infect cell cultures. In the roller culturing of 19 of the positive samples in suspension of the MA-104 cell line in the presence of trypsin two cytopathic strains were isolated. The cell line used was more sensitive than the cells of calf kidney.

Animals↗

PubMed1984

[Isolation of the respiratory syncytial virus from calves with respiratory diseases].

Described is a respiratory enzootic in calves aged 30 to 90 days. Two cytopathic strains of the bovine respiratory syncytial virus were isolated from diseased calves in a cell culture of lamb thyroid. Clinical observations and the results of virologic and serologic investigations have revealed that mixed infections of the respiratory syncytial virus and the mucosa disease virus take part in the etiology of the respiratory enzootic described.

Animals↗

PubMed1983

[Enzyme-linked immunosorbent assay (ELISA) in rotavirus detection].

Reagents were obtained by means of which the method of the enzyme-linked immunosorbent assay (ELISA) was worked out, based on the double sandwich principle, for the demonstration of rotavirus antigen presence in the fecal samples. The reaction makes use of polyvinylchloride plaques that are employed in tablet packing, and enables the rapid quantitative diagnosis of rotaviral enteritis in both animals and humans. The specificity of ELISA has been demonstrated through the comparative investigation of various viruses and bacterial antigens as well as by means of the periodic study of experimentally infected calves. The investigation of a total of 207 fecal samples from diseased calves showed that 28.5 per cent reacted positively for rotaviruses by the immunodiffusion test, and 42 per cent--by ELISA. Rotavirus enterites showed an expressed age-associated curve from the first to the fifteenth day of age with a peak between the fourth and the seventh day.

Animals↗