A Cell Line Adapted Infectious Laryngotracheitis Virus Strain (BΔORFC) for in ovo and Hatchery Spray Vaccination Alone or in Combination with a Recombinant HVT-LT Vaccine

Maekawa, Daniel; Riblet, Sylva M.; Whang, Patrick; Alvarado, Ivan; Garcı́a, Maricarmen

doi:10.1637/aviandiseases-d-20-00050

Cited by 3 publications

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“…Last, for the group of chickens solely vaccinated with the trivalent rHVT-ND-LT vaccine, a decrease of challenge virus replication in the trachea was not observed, and transmission to contact-naive chickens was evident. In contrast, it has been experimentally proved that vaccination with the bivalent rHVT-LT expressing gD and gI genes consistently ameliorates the replication of the challenge virus when tested in SPF chickens (15,26,27), broilers (28), and commercial layer hens (25). Whether the effectiveness of the trivalent rHVT-ND-LT vaccine to mitigate challenge virus replication when administered by itself is not as robust as that of the bivalent rHVT-LT vaccine needs to be further evaluated.…”

Section: Discussionmentioning

confidence: 99%

“…For example, the combination of rHVT-LT + CEO vaccination provided a more robust protection than vaccination with HVT-LT alone; and priming with rHVT-LT reduced CEO virus replication that consequently buffered the CEO postvaccination reaction (14). Also, when combining rHVT-LT with the ILTV gene-deleted strain (BΔORFC), administered in ovo or via spray at 1 day of age, improved protection against ILT (15). The objective of this study was to evaluate the protective efficacy of the trivalent rHVT-ND-LT recombinant and the live attenuated TCO vaccine when administered by themselves or sequentially in long-lived birds.…”

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confidence: 99%

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Protection Efficacy of Recombinant HVT-ND-LT and the Live Attenuated Tissue Culture Origin Vaccines Against Infectious Laryngotracheitis Virus When Administered Individually or in Combination

2023

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Infectious laryngotracheitis (ILT) is a respiratory disease that causes significant economic losses to the poultry industry. Control of the disease is achieved by vaccination and implementation of biosecurity measures. The use of bivalent and trivalent recombinant herpesvirus of turkey (rHVT) vaccines expressing infectious laryngotracheitis virus (ILTV) genes has increased worldwide. In the United States, vaccination programs of long-lived birds (broiler breeders and commercial layers) against ILT include immunizations with either HVT recombinant vector vaccines, in ovo or at hatch, or live attenuated vaccines administered via drinking water (chicken embryo origin [CEO]) or eye drop (tissue culture origin [TCO]). The efficacy of bivalent rHVT-LT at hatch followed by drinking water or eye-drop CEO vaccination has been shown to provide more robust protection than rHVT-LT alone. The objective of this study was to evaluate the protection efficacy of a commercial trivalent rHVT-ND-LT when administered at 1 day of age followed by TCO vaccination via eye drop at 10 wk of age. Groups vaccinated with only rHVT-ND-LT or TCO, the combination of rHVT-ND-LT þ TCO, and one nonvaccinated group of chickens were challenged with a virulent ILTV strain at 15 wk of age. After challenge, mortalities were prevented only in the group of chickens vaccinated with the rHVT-ND-LT þ TCO. Clinical signs of the disease and challenge virus replication in the trachea were significantly reduced for both the rHVT-ND-LT þ TCO-and TCO-vaccinated groups of chickens. To assess challenge virus transmission, contact-naive chickens were introduced to all vaccinated groups immediately after challenge. At 8 days postintroduction, infection of contactnaive chickens was evidenced in those introduced to the rHVT-ND-LT and TCO group but prevented in the rHVT-ND-LT þ TCO group. Overall, these results indicated that compared to rHVT-ND-LT or TCO when administered alone, the rHVT-ND-LT þ TCO vaccination strategy improved protection against disease and reduced shedding of the challenge virus.RESUMEN. Eficacia protectora de las vacunas recombinantes HVT-ND-LT y las vacunas con virus vivo atenuado con origen en

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