Potency of Veterinary Rabies Vaccines Marketed in Sri Lanka

Abstract

Seven brands of veterinary rabies vaccines are commercially available in Sri Lanka, but there is no established procedure to test the potency of the vaccines at the local level, especially prior to their release. The aim of this study was to test the potency of these vaccines using a mouse challenge test in collaboration with the EU/WOAH/WHO Reference Laboratory for Rabies, ANSES-Nancy, France. Based on the European Pharmacopoeia, the inactivated rabies vaccines complied with the mouse potency test if the estimated potency is ≥1.0 IU in the smallest prescribed dose. Among the eight tested vaccines, four single-dose preparations (Rabisin™, Raksharab™, Nobivac™ RL, and Nobivac™ Rabies) were compliant, with potencies of 12 IU/dose, 7.2 IU/dose, 4.4 IU/dose, and 3.4 IU/dose, respectively. Three of the single-dose preparations (Canvac™ R, Defensor™ 3, and Rabies killed vaccine) were not compliant, with potency values <1.0 IU/dose. One multidose preparation (Raksharab™ multidose) had a potency of 1.3 IU/dose, even though the test was not validated. Based on these results, it appears that some rabies vaccine batches that are currently available in the local market do not comply with the mouse potency test. Testing the vaccines’ potency before registration and release to the market appears to be an important step to allow good immunization to animals during pre-exposure vaccination programs.

Comparative Neutralization Activity of Commercial Rabies Immunoglobulin against Diverse Lyssaviruses

“…Although there is a strong correlation between the antibody titers determined using virus neutralization tests and ELISAs, the antibody titers obtained using ELISA are typically higher and more variable compared to RFFIT [ 69 , 70 ]. A study on the potency of veterinary vaccines in Sri Lanka demonstrated that the potency of some vaccines is lower than stated by the manufacturer [ 71 ]. The potency of some RIG preparations may therefore be lower than stated by the manufacturer, especially if ELISA was used with a vaccine strain as the capture antigen.…”

Determination of immunogenicity and potency of canine anti-rabies vaccines marketed in Sri Lanka: A Proposal on an experimental study using rabbits as the animal model and field study using sample dog population.

“…Also, the potency test results of all the ARVs were published in an international journal. 53 Dogs are recruited under three age categories. Blood samples are collected before the vaccination and 30 days after the vaccination.…”

Rabies vaccination induces a CD4+ TEM and CD4+CD8+ TEMRA TH1 phenotype in dogs

“…96-well plates were coated with 2 μg/mL of commercially available recombinant RABV-G (ab225663, Abcam) or RABV-N (LS-G21410-20, LSBio). Recombinant RABV-G was derived from the Pasteur strain, the same strain used in the canine rabies vaccine, whereas recombinant RABV-N (LSBio) was derived from the Pitman-Moore 1503 strain which shares 98% identity with the Pasteur strain ( S7 Fig ) [ 29 ]. Duplicated 6-point serial dilutions were performed on thawed plasma samples using a blocking buffer consisting of 1% bovine serum albumin (BSA).…”