In vitro assessment of the potency of some Newcastle disease vaccine brands in Ibadan, Nigeria

Background: Newcastle disease (ND) is a very common and economically important disease of poultry. There is no drug for treatment of the disease during an outbreak in poultry flocks, and prevention by vaccination is one of the recommended control measures. However, post vaccination outbreaks have been observed on many occasions in chicken flocks and one of the causes has been attributed to possible failure of vaccine to confer immunity. This study was designed to evaluate the potency of ND vaccines available in Ibadan, Nigeria.\r\nMethodology: Haemagglutination (HA) technique and elution phenomenon were employed to evaluate the potency of ND vaccines randomly selected in Ibadan. A total of 45 vaccines comprising 9 brands and 5 different strains were selected for potency test. The vaccine brands included ‘Vireo 116’ (n=10), ‘ABIC’ (n=5), ‘Biovac’(n=9), ‘Nobilis’(n=3), ‘NVRI’(n=12), ‘R2B’ (n=2), ‘BAL-ND’ (n=2), ‘Forte dodge’(n=1) and ‘Jovac’ (n=1), while the vaccine strains in the brands included Lasota, B1, Clone, Komarov, Hitcher, and an unknown strain.\r\nResults: Thirty-five of the 45 (77.8%) ND vaccines tested had more than 4 HA titer (\u003e64) and were therefore regarded as potent. All the 15 (100%) ND Lasota vaccine strain, 7 out of 10 (70%) ND Komarov strain, 4 out of 5 (80%) ND clone and 5 out of 8 (62.5%) ND B1 strains were potent. None of the ND brand ‘R2B’ vaccine as well as Hitchner strain from ‘Nobilis’ brand was potent, but all 5, 2, 1 and 1 vaccines tested from brands ‘ABIC’, ‘BAL-ND’, ‘Fort dodge’ and ‘Jovac’ respectively were potent. Similarly, 9 of 10, 6 of 9, 2 of 3 and 9 of 12 vaccine strains tested from brands ‘Vireo 116’, ‘Biovac’, ‘Nobilis’ and ‘NVRI’ were respectively potent\r\nConclusion: The occurrence of ND vaccines that are not potent in this study may be contributing to post vaccination failure. It is advisable to subject vaccines to potency test before use.\r\nKey words: in vitro, assessment, potency, Newcastle disease, vaccine brands, vaccine strains\r\n \r\nFrench Title; Evaluation in vitro de la puissance de certaines marques de vaccins contre la maladie de Newcastle a Ibadan, Nigeria\r\nContexte: La maladie de Newcastle (ND) est une maladie tres courante et economiquement importante des volailles. Il n\u0027existe aucun medicament pour le traitement de la maladie lors d\u0027une epidemie dans des troupeaux de volailles, et la prevention par vaccination est l\u0027une des mesures de controle recommandees. Cependant, des flambees post-vaccination ont ete observees a de nombreuses reprises dans des troupeaux de poulets et l\u0027une des causes a ete attribuee a un eventuel echec du vaccin a conferer l\u0027immunite. Cette etude a ete concue pour evaluer la puissance des vaccins contre la MN disponibles a Ibadan, au Nigeria. \r\nMethodologie: La technique d\u0027hemagglutination (HA) et le phenomene d\u0027elution ont ete utilises pour evaluer la puissance des vaccins contre la MN selectionnes au hasard a Ibadan. Un total de 45 vaccins comprenant 9 marques et 5 souches differentes ont ete selectionnes pour le test d\u0027activite. Les marques de vaccins comprenaient \u0027Vireo 116\u0027 (n=10), \u0027ABIC\u0027 (n=5), \u0027Biovac\u0027 (n=9), \u0027Nobilis\u0027 (n=3), \u0027NVRI\u0027 (n=12), \u0027R2B\u0027 (n=2), \u0027BAL-ND\u0027 (n=2), \u0027Forte dodge\u0027 (n=1) et \u0027Jovac\u0027 (n=1), tandis que les souches vaccinales des marques comprenaient Lasota, B1, Clone, Komarov, Hitcher et une souche inconnue. \r\nResultats: Trente-cinq des 45 vaccins contre la MN testes (77,8%) avaient plus de 4 titres en HA (\u003e64) et etaient donc consideres comme puissants. Toutes les 15 (100%) souches de vaccin ND Lasota, 7 souches sur 10 (70%) ND Komarov, 4 sur 5 (80%) clones ND et 5 sur 8 (62,5%) souches ND B1 etaient puissantes. Aucun des vaccins ’R2B’ de marque ND ni la souche Hitchner de la marque ’Nobilis’ n\u0027etaient puissants, mais tous les vaccins 5, 2, 1 et 1 testes des marques ‘ABIC’, ‘BAL-ND’, ‘Fort dodge’ et ‘Jovac’ respectivement etait puissant. De meme, 9 des 10, 6 des 9, 2 des 3 et 9 des 12 souches vaccinales testees des marques ’Vireo 116’, ‘Biovac’, ‘Nobilis’ et ‘NVRI’ etaient respectivement puissantes \r\nConclusion: La presence de vaccins contre la MN qui ne sont pas puissants dans cette etude peut contribuer a l\u0027echec post-vaccinal. Il est conseille de soumettre les vaccins a un test de puissance avant utilisation.\r\nMots-cles: in vitro, evaluation, puissance, maladie de Newcastle, marques de vaccin, souches vaccinales