Validation Of VAXXITEK® HVT+IBD Vaccine Intake Kinetics In Chickens Using VHVT13-Specific QPCR And Serology

Morillon P., Digoin S., Ruoven N., Oberhauser B., Albaric O. & Lemiere S. | 16th WVPAC Marrakesh | 2009

 

The objectives were to study the effect of spray vaccination against Newcastle Disease (ND) with live vaccine AVINEW® on VAXXITEK HVT+IBD (Herpes Virus Turkey + Infectious Bursal disease) vaccine intake, as well as the effect of the re-vaccination using VAXXITEK HVT+IBD in half-day interval. Four groups of conventional day-old chicks (F15, Hubbard S.A.S. Quintin, France) were reared on the floor in controlled conditions. All groups were vaccinated with VAXXITEK HVT+IBD at the hatchery. G1: no re-vaccination, no ND vaccination, G2: VAXXITEK HVT+IBD re-vaccination at day-old, G3: VAXXITEK HVT+IBD revaccination at day-old and AVINEW spray at day-old, G4: no re-vaccination and AVINEW spray at day-old. Parameters of study were vHVT13 RT-PCR replication kinetics (D21, D28, D35, D42, D56) (Table 1), ELISA serology (ProFLOK® Plus IBD and IBD ELISAs, Synbiotics Corporation, Kansas City, MO, United States of America) (Table 2) and Hemagglutination Inhibition (HI) ND serology (D21, D42, D56). Comparison between G1 & G4, then between G2 & G3 enabled assessment of the effect of ND live vaccination on VAXXITEK HVT+IBD vaccine intake. Comparison between G1 & G2 enabled assessment of the effect of re-vaccination with VAXXITEK HVT+IBD in the field after hatchery vaccination on VAXXITEK HVT+IBD intake. Safety of vaccination programs was studied in all groups by zootechnical parameter monitoring (bodyweight) and histopathology on organs at slaughter (bursa of Fabricius, thymus, Harderian gland, spleen, liver, kidney, proventriculus, small intestine, caecal tonsil, sciatic nerve). Seroconversion against ND was observed following AVINEW vaccination. ND HI titres were above the baseline in vaccinated groups (G4 > G1 and G2 > G3, significant difference, alpha risk of 5%). No effect of double vaccination (no significant difference between G1 & G2), nor effect of AVINEW vaccination (no significant difference between G1 & G4 and between G2 & G3) were observed considering ELISA Plus IBD results. IBD ELISA serological profile was characteristic of a decrease of maternally-derived antibodies without wild IBD circulation, nor classical IBD strain circulation. vHVT13 RT-PCR replication studies showed no difference between the groups. No lesions of any organ were shown at slaughter. VAXXITEK HVT+IBD was proven safe and at the origin of a fully developed intake in the conditions of repeated ®VAXXITEK is a registered trademark of Merial in the United States and elsewhere; AVINEW is a registered trademark of Merial in France and elsewhere injection (field injection after hatchery injection) and vaccination against live Newcastle vaccine.

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