Effects of T-2 Toxin on Turkey Herpesvirus–Induced Vaccinal Immunity Against Marek's Disease

• Published in: Avian diseases Vol. 60; no. 1; pp. 56 - 62
• Main Authors: Kufuor-Mensah, E, Reed, W M, Sleight, S, Pestka, J, Fadly, A M, Dunn, J R
• Format: Journal Article
• Language: English
• Published: United States American Association of Avian Pathologists 01.03.2016
• Subjects: Animals; Chickens; Female; Herpesvirus 1, Meleagrid - immunology; Herpesvirus 2, Gallid - immunology; Male; Marek Disease - immunology; Marek Disease - virology; Poultry Diseases - immunology; Poultry Diseases - virology; T-2 Toxin; Vaccination - veterinary; Viral Vaccines - immunology; mycotoxin; T-2 toxin; Marek's disease; vaccination
• ISSN: 0005-2086; 1938-4351
• DOI: 10.1637/11245-072815-Reg.1

T-2 toxin, a very potent immunotoxic Type A trichothecene, is a secondary metabolite produced primarily by Fusarium spp., which grows on cereal grains and can lead to contaminated livestock feed. Repeated exposure to T-2 toxin has been shown to cause immunosuppression and decrease the resistance of exposed animals to a variety of infectious diseases; however, the effects of T-2 toxin on Marek's disease (MD) vaccinal immunity have not been reported. Four trials were conducted to determine the effects of T-2 toxin on vaccinal immunity against MD. Day-old, white leghorn chicks of Avian Disease and Oncology Laboratory line 15I₅ × 7₁ were treated daily for 7 days via crop gavage with T-2 toxin at a sublethal dose of 1.25 mg/kg body weight. Treated and untreated chicks were also vaccinated with turkey herpesvirus (HVT) at hatch and were challenged with the JM strain of MD virus (MDV) at 8 days of age. Chickens were tested for HVT viremia at 1 wk postvaccination immediately before challenge, and for HVT and MDV viremia at 3 wk postchallenge. Chickens were observed for the development of MD lesions and mortality within 8 wk of age. T-2 toxin significantly reduced body weight and titers of HVT viremia within 7 days after hatch. T-2 toxin shortened the incubation period for the development of MD lesions and mortality, but only in unvaccinated chickens. The percent MD protection in T-2–toxin-treated, HVT-vaccinated chickens ranged from 82% to 96% and was comparable to that in HVT-vaccinated untreated control chickens (89%–100%). The data suggest that exposure of chickens to sublethal doses of T-2 toxin for 7 consecutive days after hatch may influence the development of 1) HVT viremia; and 2) MD lesions and mortality, but only in unvaccinated chickens.