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Biomedical subjects

G Ignatov

Publications and source records attributed to G Ignatov.

At least 37 records · Page 2Linked to original sources
PubMed1978

[Concentration and purification of the infectious bovine rhinotracheitis virus (IBR)].

Various combinations of the method for the concentration and purification of the IBR virus have been tested. An easily applicable pattern is adopted with whose aid the virus is rapidly purified with a slightly reduced infectability. The pattern includes concentration of the virus through precipitation with polyethylenglycol, gel-filtration on a Sepharose 4B column and ultra-centrifugation in a linear gradient of sucrose. The virus is checked electronmicroscopically, immunoelectrophoretically and through a bioassay on a rabbit. When a rabbit is hyperimmunized with a virus thus purified, a high titre antiserum is obtained in which antibodies against bovine protein are lacking.

Animals↗
PubMed1978

[Isolation of adenovirus type 1 from aborted cattle fetuses].

Five adenoviral strains, typed as adenovirus type 1, were isolated from aborted cattle foetuses, taken from farms with abortions in cows. The viruses were isolated from kidneys, lungs and livers of the foetuses. They were isolated from the kidney most frequenty (three strains). Intranuclear basophilic inclusions in the alveolar epithelium of the lungs and in the tubular epithelium of the kidneys have been established in the histological investigations of the internal organs of the foetuses. The isolation of adenoviruses from foetuses has been discussed as an infectious process, emerging as a result of a transplacental infection.

Abortion, Veterinary↗
PubMed1978

[Density gradient and ultrastructure of bovine adenovirus type 1].

Isolated and purified were virions and hexones from the bovine adenovirus type 1. The infectious virions were of equilibrium density of 1.34 g/cm3, and the empty capsids--of 1.305 g/cm3. The virions had a facet length of 43.5 nm, their size being 82.7 nm (distance between opposite poles) to 74.0 nm (diameter of the virion). The fibers of the bovine adenovirus type 1 measured 26.0--28.0 nm. The virus was destroyed by 30 per cent formamide, yielding free hexones of 1.290 g/cm3 of equlibrium density. The hexones were 10.0-12.0 nm high, were thicker at their base, and possessed a central cavity. Beside single hexones groups of 9 hexones each were also found in the soluble components (being of a left and a right type according to the arrangement of the capsomeres in them). It was demonstrated serologically that the hexones possessed 2 antigen determinants which retained their antigenic activity even after the hexones degraded and lost their morphologic type.

Adenoviridae↗
PubMed1977

[Biological properties of the dermopathic bovine herpes (Allerton-mammillitis) virus].

The dynamics of accumulation and localization of the virus antigen in cells of calf kidney (line CK) was followed by means of immunofluorescence technique. The antigen was detected eight hours (at the very earliest) after infecting the cells. Studied was the immune response of calves vaccinated with an inactivated virus and the addition of an adjuvant. Two weeks following revaccination high titres of virus-neutralizing and complement-fixing antibodies were established in the blood serum of the calves. These results made it reasonable to believe that the inactivated virus is suitable as a vaccinal antigen.

Animals↗
PubMed1977

[Test of an attenuated viral strain of TGE as a vaccine].

A live vaccine was produced using a local strain P of the virus of the transmissive gastroenteritis, arrenuated in cell cultures. The vaccinated pregnant sows had high-titer serum and colostrum virus-neutralizing antibodies. In the first days following farrowing there were in the colostrum ummunoglobulins of the Igg class that prevailed, however, IgA and IgM proved more effective in the virus-neutralizing test. Newborn pigs acquired passive immunity at about the 24th hour after the intake of colostrum. They withstood a challenge with a virulent virus.

Animals↗
PubMed1977

[Demonstration of the infectious rhinotracheitis-pustular vuluovaginitis virus (IBR-IPV) in the placenta and aborted fetuses of cows].

A well expressed correlation was found to exist between the immunofluorescence and the histologic methods in the demonstration of IBR-IPV infection of fetuses and placentae in 75 cases of spontaneous undiagnosed abortions. If those that were positive by the immunofluorescence method were 100 per cent as many as 87 per cent of them showed coincidence with the results obtained by the histologic method. The isolation of the virus of IBR-IPV coincided in 44 per cent of the cases only. Clearest specific fluorescence, established most frequently, was demonstrated in the kidneys of the fetuses. It was found that contrast staining with Evans blue effectively inhibited the unspecific fluorescence. Exceptions in this respect were observed with some preparations of liver, lung, and placental tissues, where there were cells of unspecific fluorescence, which, by its character and localization differed essentially from the fluorescence that was specific for IBR-IPV. It is assumed that the immunofluorescence method performed at contrast staining with Evans blue makes possible the fast and precise diagnosis of IBR-IPV.

Abortion, Veterinary↗
PubMed1977

[Group and type antigenic specificity of bovine adenovirus type 1 hexons].

Hexones were obtained from the bovine serotypes 1 and 3. They were investigated through the complement-fixation test along with intact virions in the presence of a hemotype and a heterotype antiserum. It was shown that the free hexones were twice as reactogenic in the homotype system as compared to the heterotype one. The hexones were found to possess two antigenic determinants--a typespecific one and a group-specific one. The latter proved sensitive to chymotrypsin. Intact vicions reacted chiefly type-specifically. Discussed is the problem of the space disposition of the type -and group-specific antigen determinants of the hexones in sito in the virions.

Adenoviridae↗
PubMed1977

[Morphology of bovine adenovirus type I].

Electron-microscopic studies were carried out on a concentrated and purified adenovirus type I. It was found that its morphologic aspects were characteristic of the adenovirus group. In the preparations of this virus there were large amounts of incomplete virions and soluble components--hexons, groups of hexons and pentons. Some of the virions were grouped in p-crystal structures or were released as grouped in cell vacuoles. The hexons presented a six-angle contour and a central cavity. The pentons possessed fibre components that were comparatively long. The presence of free pentons spoke of the existence of incomplete hemagglutinins.

Adenoviridae↗
PubMed1976

[Immunogenic properties of a polyvalent inactivated vaccine from respiratory viruses (IBR, Pi-3, Ad-1, Ad-3].

Studied was the authors' inactivated polyvalent vaccine having an adjuvant, prepared from the respiratory viruses IBR, Pi-3, Ad-1 and Ad-3. It was found that at the subcutaneous vaccination of calves and pregnant cows there were virus-neutralizing, hemagglutination-inhibition, and complement-fixing antibodies as established by the 14th day following treatment. Revaccination was carried out on the twenty-eighth day when the antibodies reached high titers. The latter showed peak values on the 14th day following revaccination. The prevaccinal and vaccinal antibodies did not interfere with the process of immunogenesis. The virus-neutralizing antibodies against IBR had a titer of 5 log on the 150th day, while the virus-neutralizing and hemagglutination-inhibition antibodies against Pi-3 showed the same titer even after the 180th day following vaccination. There were in the milk of the vaccinated cows, in the seventh month of pregnancy, specific lactoglobulins of the IgA and IgG classes which were contained in the 27-36, 45-48 and 51-54 fractions, distributed in three peaks by their protein content. The level of the virus-neutralizing, hemagglutination-inhibition, and complement-fixing antibodies against the inactivated vaccinal respiratory viruses showed that the subcutaneous treatment with the polyvalent vaccine leads to the production of antibodies that are secreted with milk

Adenoviridae↗
PubMed1976

[Use of polyethylene glycol (PEG) in the isolation of the IBR virus].

Experiments were carried out to use polyethylene-glycol (PEG)--6000 in the isolation of the IBR virus from field material. The sedimentation with PEG proved easy, fast and selective. Large amounts of field material suspension could be treated which made it possible to attain volume concentration of such suspensions and to raise the relative concentration of the virus in them. Thus the virus could be isolated more quickly and in a more dependable way, avoiding the toxic effect of some of the initial materials on the cell culture.

Animals↗
PubMed1976

[Testing the preventive properties of polyvalent inactivated vaccine (IBR, PI-3, Adenovirus 1,3) at a cattle-breeding farm].

Tested was an inactivated polyvalent vaccine. It was shown to produce virus-neutralizing antibodies against the respiratory viruses in high titers. The vaccine proved highly immunogenic, reactogenic, and harmless in doses of 2,3,5,7, and 10 cm3 for 30-45-day-old calves and pregnant cows in their 7th or 8th month of pregnancy. The morbidity rate among the unvaccinated calves ranged from 51 to 66 per cent, and among the vaccinated ones it was from 0 to 5 per cent on the four farms studied. The abortions caused by the IBR vicontrol was cows about 17 per cent, and with the vaccinated ones it was 1.14 per cent. Calves born by untreated control cows contracted respiratory virus infections (76 per cent), while calves from vaccinated cows did not. When there was an acute virus respiratory disease on the farms all calves were treated with a hyper-immune serum against respiratory viruses, and after recovery of the herd vaccinations and revaccinations of all calves were carried out. Discussed is the problem of the protection properties of the vaccine in the case of pregnant cows and its advantages as compared with the live vaccines in order to discontinue the transmission of live viruses onto the industrial cattle-breeding farms.

Adenoviridae Infections↗
PubMed1975

[Use of the direct immunofluorescence method for determination of the TGE viral antigen in swine].

Followed up were the appearance and accumulation of the transmissive gastroenteritis (TGE) virus antigen in infected cells of pig kidney and thyroid. Used were specific conjugates, such introduced by the authors and some imported from Czechoslovakia. The cell cultures were infected with strains of the TGE virus, isolated in Bulgaria or supplied from Czechoslovakia. It was found that the Bulgarian strains were the same as those from Czechoslovakia and the United States. A viral antigen was found as early as the sixth hour following the infection of the cell cultures and it appeared under the form of cytoplasmatic yellow-green fluorescence. By the 12th, and up to the 18th hour the number of the specifically fluorescing cells as well as the intensity of fluorescence itself increased. Highest values in this respect were noticed in the interval between the 36th and 48th hour after the cultures had been infected.

Animals↗
PubMed1975

[Some properties of strains of the transmissible gastroenteritis virus of swine (TGE) isolated in Bulgaria].

Strains of the swine transmissive gastroenteritis (TGE) virus were isolated for the first time in Bulgaria in 1972. The dynamics was followed up of some strains' propagation in primary cell cultures of kidney tissue and subcultures of the thyroid of pigs. The intracellular virus reached highest titers at the 24--48th hour in the kidney cells, and at the 24--36th hour in the thyroid cells, while the extracellular virus was subjected to inactivation by the 2nd hour after infecting the cultures, by the 4--6th h its titer dropped up to 50 per cent of its initial value, and by the 24th h it was completely inactivated. The viability of the virus was tested after freeze-drying and after it had been stored at 4degreesC and--20degreesC. It was found that chloroform fully inactivates the virus at 4degreesC for 24 hours. The same results were obtained with the use of sodium desoxycholate. The strains isolated in this country form plaques, and with some strains the plaques are of a varying size. Halogenic desoxyuridines (IUDR, BUDR), as well as 8-azoridine do not suppress the multiplication of the tested TGE strains even in high concentrations. Inhibitory effect has 5-bromurazyl which in given concentrations affects the titer of the virus and the size of the plaques formed. Two Bulgarian and two reference strains have lowered their plaque-forming titer by 2 log after being treated with rifamycin-B or rifampicin.

Animals↗