Revista de la Asociacion Argentina de Microbiologia最新文献

This paper describes two experiments carried out in cattle immunized with suckling mouse brain rabies vaccine (SMB) 14, supplemented with 2% Al (OH)3 15 or Freund's modified incomplete adjuvant 2, 26. When determining the vaccinal dose, it was observed that the immune response was independent from the doses used (Table 1), all animals survived the challenge 30 days after vaccination, as compared to a mortality rate of 80% in the controls. To determine the duration of immunity, an amount of 5 ml was chosen as vacinal dose. Two years after immunization, both vaccines protected 96% of the cattle against a viral challenge that killed 63% of the non-vaccinated controls (Table 2). Statistically significant differences were observed between the antibody levels elicited by both vaccines. Antibody levels observed with the oil supplemented vaccine were higher than those produced by the A1 (OH)3 vaccine.

Immunodiffusion and immuno-electrophoresis techniques were used to detect rabies precipitable antigens. The passive haemagglutination test with group "O" human red cells treated with tannic acid, was used as control test. The study was done with brain suspensions of rabies virus infected mice (CVS strain). Mouse and horse rabies antisera were used. The analysis of the results of both immunochemical assays showed the presence of two specific antigenic fractions of rabies virus. The same two fractions were detected when the antigens were heated. Experiments with brain extracts centrifuged at high speed, suggested that the antigenic fractions are of the "soluble" type.

Twenty seven per cent of 238 serum samples obtained from horses with clinical diagnosis were positive for the immunodifusion test, while 17% of the 452 sera obtained from asintomatic horses were positive. Twenty one per cent of the 870 sera studied were positive.

The nucleic acids and protein content in epimastigote forms of Trypanosoma cruzi during its exponential growth in vitro were studied. The parasites were cultivated in a diphasic blood-agar medium at 28 degrees C. The RNA extraction and hydrolisis were performed by the method of Fleck and Begg and the acid hydrolisis of DNA precipitate was done according to Webb and Lindstrom. Schneider's colorimetric method was used for ribose and desoxyribose measurement, employing as reagents orcein and diphenylamine respectively. Protein content was determined by the method of Lowry et al. Calf thymus DNA, yeast RNA and bovine plasma albumin were used as standards. It was established that 1.00 g of wet parasites contained 1.05 (+/-0.17) X 10(10) epimastigote forms. The contents of DNA, RNA and protein were 6.1, 12.3 and 105.4 mg/g of wet epimastigote, or 5.8, 11.7 and 100.1 X 10(-7) microgram per epimastigote, respectively. The method employed for nucleic acid determinations did not show great differences when compared with the Schmidt Thamhauser-Schneider technique, and it has the advantage of being more rapid.

A seroepidemiologic investigation was carried out in order to remake the experience of the population of Rosario, Argentina, with different strains of virus influenza type A (prototype strains and minor variations). PR/8/34 (HO N1); FM/1/47 (H1 N1); R/1/62 (H2 N2); HK/1/68 (H3 N2); E/42/72 (H3 N2); PCh/1/73 (H3 N2). It could be established that the tested strains circulated in this City, probably while they prevale in other parts of the world. A 34,6% of recent infections for the prevalent strains could be estimated from the present investigations.

A fraction from Swiss albino mouse brain homogenate obtained by DEAE cellulose chromatography showed a non-specific hemagglutination-inhibitory property for some Togaviruses. Evidence are presented indicating that the inhibitory property is related to a protein-rich fraction with sialic acid as an active group.