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Biomedical subjects

A M Díaz

Publications and source records attributed to A M Díaz.

31 records · Page 2Linked to original sources
PubMed1981

Comparison between a modified counterimmunoelectrophoresis test and the indirect fluorescent-antibody test for detection of antibodies to rabies virus in human sera.

The correlation between the modified counterimmunoelectrophoresis test and the indirect fluorescent-antibody test for detecting rabies virus antibodies in human sera was studied, using as a reference the standard mouse neutralization test. Higher sensitivity was observed with the counterimmunoelectrophoresis technique than with the indirect fluorescent-antibody method. The counterimmunoelectrophoresis test provides a practical quantitative alternative to the indirect fluorescent-antibody method.

Antibodies, Viral↗
PubMed1980

Determination of serum neutralization antibodies to rabies virus by a modified counterimmunoelectrophoresis test.

A modified counterimmunoelectrophoresis (CIE/SN) technique was developed as a diagnostic procedure for the detection of serum-neutralizing antibodies to rabies virus. CIE/SN test results with sera from individuals undergoing postexposure rabies immunization compared favorably with those obtained by the standard mouse neutralization test procedure. Fractionation of selected sera by Sephadex G-200 column chromatography demonstrated that serological activity involved in both procedures was present in the immunoglobulin G-containing fractions of the sera. The mean advantage of the CIE/SN over the standard mouse neutralization test consists in considerably reducing the time required for results, a factor which can be of clinical importance in evaluating antibody levels to rabies virus. In addition, the CIE/SN method is simple to perform and inexpensive.

Animals↗
PubMed1980

Persistence and variation of Mangosta street rabies virus antigens during adaptation into mice.

A Mangosta street rabies virus strain antigen not shared by the challenge virus standard (CVS) was identified by counterimmunoelectrophoresis. This strain antigen persisted following nine mouse passages of the virus, during which the CVS strain antigen was not acquired. These observations suggest that the antigen composition of the two virus strains is different. Antigenic differences during the course of adaptation of Mangosta virus were also revealed by crossed serum neutralization tests. The findings are discussed in terms of the occurrence of variations in the number and localizaion of antigen sites in the virus and of the possible existence of antigenic competition by non-infective viral antigens in serum neutralization tests for rabies.

Animals↗
PubMed1977

Characteristics of 11 rabies virus isolates in mice: titers and relative invasiveness of virus, incubation period of infection, and survival of mice with sequelae.

Mice were inoculated intracerebrally or in the footpad with 11 salivary gland suspensions from rabid foxes, skunks, and bobcats. The 11 isolates differed in their ratios of intracerebral titer to footpad titer, a result indicating that the "invasiveness" of different isolates varies markedly. The degree of invasiveness could not be correlated with the species of animal. The inoculation of the less invasive isolates resulted in an appreciable number of permanently paralyzed animals (survivors with sequelae). These animals had high titers of neutralizing antibody in serum but no neutralizing antibody in the brain, a finding suggesting that virus had invaded only the peripheral nervous system or the spinal ganglia. Pathological examination of the paralyzed mice and normal mice confirmed this finding.

Animals↗
PubMed1976

Detection of antigenic differences among street and fixed rabies virus strains by the counterimmunoelectrophoresis test.

Using the counterimmunoelectrophoresis test, two street rabies virus strains (Mangosta and Apipe) revealed antigens not detected in the standard challenge virus (CVS). No antigenic differences, however, were found between CVS and another fixed rabies virus strain (strain 91) by this method. The results of serum neutralization tests revealed similar antigenic relationships among the rabies virus strains studied. These findings are discussed in terms of their significance to antigenic variations in rabies virus strains.

Counterimmunoelectrophoresis↗
PubMedDate not supplied

Hyperimmune antirabies sera titration by standard mouse neutralization and counterimmunoelectrophoresis tests, comparing results of different laboratories.

To determine the rabies antibody level of twenty-four hyperimmune equine sera, Standard Mouse Neutralization (SMN) and Couterimmunoelectrophoresis (CIE) tests were carried out, both at the Instituto Butantan (IB) and Instituto Panamericano de Proteccíon de Alimentos y Zoonosis (INPPAZ). Statistical analysis has shown a correlation (r) of 0.9317 between the SMN and CIE performed at the IB, while at the INPPAZ it scored 0.974. Comparison of CIE data of both laboratories yielded a correlation of 0.845. The CIE technique has shown to be a sensitive and efficient as the SMN in titrating antirabies hyperimmune equine sera. Based on CIE results, a simple, rapid and inexpensive technique, titers of sera antibody can be rellably estimated in SMN test.

Animals↗
PubMedDate not supplied

Evaluation of standard reagents for radial-immunodiffusion assays. In vitro control of rabies vaccines.

The RID assay is one of the in vitro methods used for in-process control in the production of rabies vaccines for veterinary use. It has been shown to be very useful for determining antigen concentration in the final bulk product. The work presented in this paper, including the production and standardization of candidate standard reagents for use in the Radial Immunodiffusion Assay (RID) was carried out at the Pan American Institute for Food Protection and Zoonoses (INPPAZ/PAHO/WHO). The study was completed with the cooperation of the Faculty of Veterinary Sciences, National University of La Plata (NULP), Argentina, where the validation of the proposed standards and the quality control of samples from 28 different batches of rabies vaccines produced with Pasteur strain rabies virus (PV) in BHK cells were performed. The activity of the vaccines was determined by in vivo (NIH) and in vitro (RID)assays. The results of the candidate reagents for the reagent standardization tests showed stability, sensitivity and reproducibility. The Relative Potency the 1.2 between the problem vaccines and the reference vaccine was estimated by variance and regression analysis. The results of our validation study show that the INPPAZ (PAHO/WHO) is capable of producing and distributing the above-mentioned standard reagents, as well as of providing support for the incorporation of the RID technique (sensitive, rapid and inexpensive) to the laboratories that manufacture rabies vaccines in Latin America and the Caribbean.

Animals↗
PubMedDate not supplied

[Quality of the reagents used in counterimmunoelectrophoresis technique for the determination of antirabies antibodies].

This study demonstrated that the antigens and indicator sera produced by the Butantan Institute may be employed with success in the counterimmunoelectrophoresis technique for the titration of rabies antibodies in sera from immunized individuals. No statistically significant differences were demonstrated between the results obtained in the standardization tests carried out at the Butantan Institute and the reference control tests performed at the Pan American Zoonoses Center. It is proposed that the Butantan Institute be in charge of the production and distribution of these reagents at the national level.

Animals↗
PubMedDate not supplied

[Immunization of calves with a rabies vaccine from suckling mouse brain].

This paper summarizes the results obtained in a study on the duration of immunity in calves immunized with suckling mouse brain (SMB) rabies vaccine, supplemented with aluminum hydroxide. Rabies circulating antibodies were detected ten days after vaccination in 100% of the 31 vaccinated calves. They began to decrease 90 days after immunization. Of the 15 calves challenged one year postimmunization, 5 (33%) had no detectable antibodies at serum dilution 1:5, but all were protected against the challenge dose virus which killed 75% (3/4) of the non vaccinated controls. The results obtained suggest that SMB rabies vaccine can be used successfully to immunize calves aged from 7 days to 6 months. Since 15 to 20% of the cattle population of a country is less than one-year-old, the protection of this population against rabies with an inactivated vaccine would decrease the number of susceptible animals and facilitate both the vaccination procedures and the movement of animals from rabies-free areas to those where the disease is enzootic.

Animals↗
PubMedDate not supplied

[Suckling mouse brain rabies vaccine supplemented with an adjuvant. Its use in cattle].

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.

Adjuvants, Immunologic↗