Evaluation of specific and non-specific immune response of four vaccines for caseous lymphadenitis in sheep challenged

Abstract

Background:Caseous lymphadenitis (CLA) is a serious disease affects sheep and goat, caused by Corynebacterium pseudotuberculosis. Due to it is non-treatable disease, so the effective preventive vaccines are considered a significant way to combat the disease. All strains of C. pseudotuberculosis have several virulence factors that associated with their cell invasion, survival, and proliferation such as phospholipase D (PLD), outer lipid coat, and secreted proteases.Aim:The present study was directed to perform a comparative innate and acquired immune response assessment of different four vaccine formulas to evoke protection against induced (CLA) challenge in sheep.Materials and Methods:Negative ELISA (free of CLA) 15 local breed male (Balady) sheep were divided into five groups, each has received a different vaccine while the control has received saline buffer. The first vaccine composed of toxoid PLD alone the second composed of toxoid PLD with bacterin (formalinkilled bacteria), the third vaccine composed of toxoid PLD plus covaccine 8, while the fourth one composed of toxoid PLD plus locally produced polyvalent clostridial vaccine. The specific immune response was evaluated through lymphocyte proliferation assay using ELISA BrdU kit, while the non-specific response was estimated by superoxide anion production and lysozyme activity assays.Results:The study revealed that PLD toxoid could evoke the highest specific immune response, showing a stimulation index (9.12%). On the other hand, combined toxoid ↱PLD with bacterin followed by PLD toxoid showed a significant increase in the non-specific innate immune response.Conclusion:The present study indicated that the toxoid PLD alone vaccine was most efficient and provided innate and acquired immune response in animals against CLA.

Bacteriological, molecular and histopathological evaluation of four vaccines’ protective role against caseous lymphadenitis in sheep

“…However, vaccination with a merged clostridial toxoid with PLD toxoid vaccine, 'either imported or locally prepared' may provide protection against C. pseudotuberculosis challenge, though to a lesser degree than sole vaccination of PLD; SI became lower '5.73' in combined vaccine recipients. (Syame et al 2018). At the same time, the decline in antitoxin levels in antibodies and the stimulation index reversed on sheep's percent protection against C. pseudotuberculosis challenge, dropping from 90% to around 80%.…”

“…Because the PLD toxoid could elicit cellular immune response which be assayed by the lymphocyte proliferation. It had the top stimulating (SI) index '9.12' with high antibody titer, the most effective immunization against CLA was given to animals vaccinated with toxoid PLD alone (Selim et al2016;Syame et al2017;Syame et al 2018). However, vaccination with a merged clostridial toxoid with PLD toxoid vaccine, 'either imported or locally prepared' may provide protection against C. pseudotuberculosis challenge, though to a lesser degree than sole vaccination of PLD; SI became lower '5.73' in combined vaccine recipients.…”

Linfadenitis caseosa: factores de virulencia, patogénesis y vacunas. Revisión

“…El grupo vacunado solo con PLD mostró una marcada respuesta positiva de proliferación de linfocitos en comparación con el resto de los grupos. Los resultados indicaron que la PLD estimuló la respuesta inmune celular específica e inespecífica (79) .…”