ABSTRACT
BACKGROUND: In newborn foals the absorption of colostrum immunoglobulins in the small intestine is maximal up to 8 hours after birth and then progressively decreases to become null after 24 hours post-partum. Thus, equine practitioners need a simple, quick, inexpensive and reliable field test to identify foals affected by failure of passive transfer rather than an accurate method yielding quantitative results within the whole range of immunoglobulin concentrations. OBJECTIVE: As the validity of the immunocrit method to detect failure of passive transfer in foals had not been evaluated before, the objective of this study was to test the ability of this method to detect the concentration of immunoglobulins in a large number of foal serum samples. STUDY DESIGN: Assay validation using samples collected for clinical purposes. METHODS: The immunocrit test, using a 40% ammonium sulphate solution, was used to measure the concentration of immunoglobulins in serum samples from 211 newborn Thoroughbred foals. The results were compared, by statistical analysis, with those of agarose gel electrophoresis, a reference quantitative method. RESULTS: The values obtained by the immunocrit method were significantly correlated (R = .871; P < .001) with those measured by agarose gel electrophoresis. A cut-off value of 8 g/L of serum immunoglobulins by agarose gel electrophoresis and its equivalent of 9.5% for the immunocrit test was indicative of failure of passive transfer. The sensitivity and specificity of the immunocrit method at this cut-off point were 94% (95% CI, 90-97.3) and 82% (95% CI, 72.13-91.8) respectively. MAIN LIMITATIONS: Variable times of sample extraction after colostrum suckling, over the study period. CONCLUSIONS: The immunocrit test provides a quantitative, quick, inexpensive, reliable and objective method to detect failure of passive transfer of maternal immunity in newborn foals, which is easy to perform directly in horse farms, with minimum laboratory equipment.
Subject(s)
Immunity, Maternally-Acquired , Immunoglobulin G , Animals , Animals, Newborn , Colostrum , Female , Horses , Pregnancy , Sensitivity and SpecificityABSTRACT
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.
Subject(s)
Animals , Laboratory Chemicals , Rabies Vaccines , Immunodiffusion/methods , Quality Control , Reproducibility of Results , Sensitivity and Specificity , Veterinary DrugsABSTRACT
El metodo recomendado por la Organizacion Mundial de la Salud (OMS) para la prueba de potencia de vacunas antirrabicas como producto final es la prueba NIH. Algunas tecnicas in vitro se han propuesto para el control durante el proceso de producion y complementan el ensayo in vivo antes mencionado. Este trabajo presenta los resultados obtenidos cuando se utilizo la tecnica de contrainmunoelectroforesis (CIE) para determinar el contenido de antigenos en muestras de 84 y 40 lotes de vacunas antirrabicas producidas em tejido nervioso de cerebro de raton lactante mediante cultivo de tejidos, respectivamente....
