Quantitative anti-PA IgG ELISA; assessment and comparability with the anthrax toxin neutralization assay in goats.

BACKGROUND: Presently, few data exist on the level and duration of anti-protective antigen (PA) IgG in vaccinated livestock. Various adaptation of enzyme-linked immunosorbent assays (ELISAs) have been developed in studies to assess immune response following vaccination, albeit mostly in laboratory rodent models. The quantitative anti-anthrax IgG ELISA in this study describes a method of enumerating the concentration of anti-PA specific IgG present in sera of immunized goats, with the aid of an affinity-purified caprine polyclonal anti-anthrax PA-83 IgG standard. This was compared with the anthrax toxin neutralization assay (TNA) which measures a functional subset of toxin neutralizing anti-PA IgG. RESULTS: The measured concentrations obtained in the standard curve correlated with the known concentration at each dilution. Percentage recovery of the standard concentrations ranged from 89 to 98% (lower and upper asymptote respectively). Mean correlation coefficient (r2) of the standard curve was 0.998. Evaluation of the intra-assay coefficient of variation showed ranges of 0.23-16.90% and 0.40-12.46% for days 28 and 140 sera samples respectively, following vaccination. The mean inter-assay coefficient of variation for triplicate samples repeated on 5 different days was 18.53 and 12.17% for days 28 and 140 sera samples respectively. Spearman's rank correlation of log-transformed IgG concentrations and TNA titres showed strong positive correlation (rs = 0.942; p = 0.01). CONCLUSION: This study provides evidence that an indirect ELISA can be used for the quantification of anti-anthrax PA IgG in goats with the added advantage of using single dilutions to save time and resources. The use of such related immunoassays can serve as potential adjuncts to potency tests for Sterne and other vaccine types under development in ruminant species. This is the first report on the correlation of polyclonal anti-anthrax PA83 antibody with the TNA in goats.

Prospects of control and eradication of capripox from the Indian subcontinent: a perspective.

Sheeppox and goatpox, two endemic capripox infections in India, pose a significant economic threat to small ruminant productivity in the subcontinent. Vaccination of all susceptible sheep and goats is the feasible and sustainable means of control. Availability of effective live attenuated vaccines that are inherently thermostable and development of improved diagnostics provide the opportunities to initiate effective control measures for capripox. All animals older than 4 months can be vaccinated with the current homologous vaccines using a single vaccination by intradermal or subcutaneous routes. The success of the control program needs to be monitored by active surveillance particularly for the presence of virus, as sero-monitoring does not enable the differentiation of infection and vaccination. And also the sero-conversion following capripox vaccination is not detectable enough by the available tools. Sustained control efforts call for socio-economic and political stability, adequate infrastructure and logistic support to store and transport vaccines for reaching out vaccines to the remote end users. Availability of veterinary services, improved extension services for increased awareness among farmers, contribute significantly to the control campaigns. Poor vaccination coverage and in-adequate infrastructure in major parts of the country are some of the major elements that come in the way of effective implementation of building herd immunity through immunization.

Imunidade passiva, morbidade neonatal e desempenho de cabritos em diferentes manejos de colostro / Passive immunity, neonatal morbidity and performance of kids in different colostrum management

Objetivando determinar o manejo de colostro que permitisse a melhor aquisição de imunidade passiva em cabritos e avaliar possíveis relações entre imunidade, morbidade e desempenho, amostras de sangue foram obtidas de 58 cabritos da raça Saanen antes e 30 horas após a primeira ingestão de colostro. Os cabritos foram distribuídos em cinco grupos experimentais. No Tratamento 1 (T1) o colostro foi ingerido ad libitum durante 24 horas. Nos demais tratamentos o colostro foi fornecido em mamadeira; os cabritos do T2 ingeriram 200mL de colostro após o parto; do T3, ingeriram 400mL de colostro sendo 200mL após o parto e 200mL após 8 horas; do T4, ingeriram também 400mL de colostro, sendo 200mL após o parto, 200mL após 14 horas; e os do T5 ingeriram 600mL de colostro, 200mL após o parto, 200mL as 12 e 200mL as 24 horas. Os valores séricos de gamaglobulinas foram avaliados por eletroforese. O ganho de peso diário foi utilizado para avaliação do desempenho no período de aleitamento. A ocorrência de doenças foi registrada do nascimento até 28 dias. A menor concentração de gamaglobulinas foi encontrada nos animais do Grupo 2 (1,65g/dL) e a maior concentração foi observada no Grupo 3 (2,60g/dL). Foi observado no Grupo 3 mais animais com diarréia, porém não foram encontradas diferenças estatísticas significativas ao nível de 5 por cento. Os diferentes manejos de colostro não estiveram associados com o desempenho dos cabritos até o final do período neonatal.

Assessment of lymphocyte and phagocytic functions in goats treated with glucan.

The effect of glucan, a biological response modifier of yeast origin, on different immune functions was studied after the intramuscular application in goats. The simultaneous administration of glucan with human serum albumin or tetanus toxoid significantly stimulated the antibody production to both antigens differing in their thymus dependency. Similarly, the phagocytizing activity of the blood polymorphonuclear leukocytes measured by the reductase colorimetric assay significantly increased one week after the glucan treatment. However, suppression of T-lymphocyte function in experimental animals was determined by the lymphocyte transformation test particularly in response to phytohemagglutinin and concanavalin A. The results of the study indicate that glucan can modulate some elements of the ruminant immune response.

Effect of temperature on the sodium sulphite precipitation test for assessment of goat serum immunoglobulin.

Total serum immunoglobulin concentrations of apparently normal indigenous goats were estimated by a sodium sulphite precipitation test which utilized 3 concentrations of the salt (i.e. 14%, 16%, 18%). A total of 210 goat serum samples comprising five phenotypically different breeds were examined. Immunoglobulin precipitation was greatly influenced by the incubation temperature. Using different concentrations of the sodium sulphite salt solution, serum samples incubated at either 4 degrees C or 38 degrees C consistently gave clear and rapid precipitation reaction in all samples with immunoglobulin concentrations of over 15 mg/ml. Tests carried out at normal tropical room temperature (28 degrees-30 degrees C) gave inconsistent results and only 52% gave clear precipitation. Neither breed nor sex had any statistically significant effect on either the precipitation rate or the immunoglobulin values (P less than 0.05). It was concluded that this test if performed at either 4 degrees C or 38 degrees C can be used under field conditions to evaluate immune status of neonatal goats in the tropics.

Assessment of mammary lactogenic receptor changes in pregnant rabbits.

Lactogenic receptor was purified from rabbit mammary tissue and used to generate an antiserum in goats. The purified lactogenic receptor material bound lactogenic hormones specifically and reversibly. Antiserum generated in a goat bound a labeled human growth hormone/receptor complex; this was displaced by nonlabeled solubilized receptor preparations. This was used as a radioimmunoassay and was able to detect 0.037 fmol of lactogenic receptor. The specificity of the radioimmunoassay for lactogenic receptor was supported by three lines of evidence; first, the ligand used in the radioimmunoassay was an iodine 125-labeled human growth hormone/receptor combination; therefore, only membrane protein with structural homology to the protein which bound 125I-labeled human growth hormone competed for binding to the antiserum; second, depletion of radioreceptor binding sites by affinity chromatography with ovine prolactin as the fixed ligand was detected; third, an increase in breast lactogenic receptor during pregnancy was detected by both radioreceptor assay and the radioimmunoassay. We found a progressive increase in lactogenic receptors by radioimmunoassay which corresponded to parallel increases by radioreceptor assay in rabbit mammary tissue during pregnancy.

Assessment of thyroid function during pregnancy.

Serum levels of thyroid stimulating hormone and of the two thyroid hormones were compared in pregnant women and in non-pregnant control subjects. Circulating levels of thyroid stimulating hormone did not alter significantly throughout pregnancy. Total thyroxine and triiodothyronine concentrations increased markedly during the first and second trimesters, associated with a progressive increase in the thyroid binding capacity of serum proteins. Urinary triiodothyronine and thyroxine excretion during the third trimester of pregnancy was comparable to that found in non-pregnant euthyroid females and, it is concluded, provides the simplest method of assessing thyroid function during pregnancy.

Assessment of the B-lymphocyte population in agammaglobulinemia.

The population of B lymphocytes was assessed in the blood of 16 patients with agammaglobulinemia using immunofluorescence and EAC1423 reactivity as B-cell markers. Lymphocytes were fractionated on gradients of bovine serum albumin which are capable of separating lymphocytes into B-cell-rich and T-cell-rich populations. There was complete absence of B lymphocytes in the majority of patients with X-linked agammaglobulinemia. Normal or increased numbers of B lymphocytes were found in all patients with common variable agammaglobulinemia.