A five-year surveillance study of vaccination schedules using viral-vectored vaccines against infectious laryngotracheitis in a high-density layer region

• Autor(a) principal: Willian Henrique de Magalhaes Santos
• Data de Publicação: 2022
• Outros Autores: Stephen J. Spatz, Roselene Ecco, Letícia Batelli de Oliveira, Philipe Anibal Leão, Izabella Hergot, Raphael Rocha Wenceslau, Christiane Maria Barcellos Magalhães da Rocha, Helena Lage Ferreira, Mauricio Resende, Nelson Rodrigo da Silva Martins
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: https://doi.org/10.1590/1678-5150-PVB-7037; http://hdl.handle.net/1843/67671; https://orcid.org/0000-0002-1545-5855; http://orcid.org/0000-0002-8052-5389; https://orcid.org/0000-0001-9051-1565; https://orcid.org/0000-0002-1008-4346; https://orcid.org/0000-0002-0034-1484; https://orcid.org/0000-0002-2012-9552; https://orcid.org/0000-0002-3261-3712; https://orcid.org/0000-0001-8925-2228
• topic: Vaccination; Vectored vaccine; Laryngotracheitis; Layer chickens; Gallid herpesvirus 1; Histopathology; PCR; Sequencing; Vacinação; Poedeiras (Galinha); Herpesvirus galináceo 1; Histopatologia veterinaria; Reação em cadeia da polimerase; Análise de sequência de DNA

The effectiveness of vectored recombinant vaccines to control infectious laryngotracheitis (ILT) in chickens from a region (State of Minas Gerais, Brazil) with ~10 million layers was evaluated under field conditions from 2014-2018. During this period, only recombinant turkey herpesvirus (rHVT) or fowl poxvirus (rFPV) vaccines that express antigens of infectious laryngotracheitis virus (Gallid herpesvirus-1; GaHV-1) were used. Layer chickens (n=1,283), from eight different egg-producing companies, were individually sampled and examined (active surveillance), and in instances when government poultry health veterinarians were notified due to respiratory disease (passive surveillance). Clinical, macroscopic, and histopathology examinations were performed to diagnose ILT as well as molecular techniques for the detection and characterization of the GaHV-1 DNA from the trachea and trigeminal ganglia (TG). The layer hens sampled and examined belonged to flocks and farms that used different vaccination protocols (non-vaccinated, single dose vaccination, and prime/boost vaccination). This is the first long-term field study of the effectiveness of ILT vectored vaccines in a high-density multiple age layer hen region. Using various diagnostic methods, the occurrence of GaHV-1 infection and ILT clinical disease in layer hens vaccinated with vectored recombinant vaccines in one quarantined region of Brazil were investigated. The number of ILTV positive chickens by PCR and ILT clinical disease cases was lower in farms when all chickens were vaccinated with at least one vaccine. However, the difference in the detection rates of GaHV-1 infection was significant only when compared farms with prime/boost and farms using single dose of HTV-LT.