Effects of cold stress and Salmonella Heidelberg infection on bacterial load and immunity of chickens.

We analysed the effects of cold stress (19 ± 1°C, 6 h /day, from the first to the seventh day of life) applied to specific pathogen free (SPF) chickens. On experimental Day 1 (ED1), chicks were divided into four groups: C (not infected and kept under thermoneutral condition); CS (not infected and cold stressed); PC (Salmonella Heidelberg (SH) infected and kept under thermoneutral condition) and PCS (SH infected and cold stressed). High concentrations of corticosterone were found in the cold stressed birds on ED7 and ED21, with a greater increase in birds of the PCS group.

Persistence and spreading of field and vaccine strains of infectious laryngotracheitis virus (ILTV) in vaccinated and unvaccinated geographic regions, in Brazil.

Infectious laryngotracheitis (ILT) is a highly infectious respiratory disease that causes morbidity and mortality in commercial chickens. Despite the use of attenuated vaccines, ILT outbreaks have been described in broiler and long-lived birds. Molecular approaches, including polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing, are used to characterize ILT viruses (ILTVs) detected in vaccinated and unvaccinated geographical regions.

Cloning and expression of chicken anemia virus VP3 protein in Escherichia coli.

Purification of chicken anemia virus (CAV) VP3 protein, expressed in a prokaryotic expression system as histidine-tagged fusion protein is demonstrated in the present study. CAV particle was obtained from infected liver of chicken and DNA was extracted. The VP3 protein gene was amplified from the extracted DNA by polymerase chain reaction (PCR) and cloned.

Lethal factor to mice produced by Escherichia coli isolated from chickens with swollen head syndrome.

A lethal toxin similar to Bacillus cererus lethal toxin was detected in the culture supernatants of Escherichia coli isolated from chickens with swollen head syndrome. The lethal activity was heat-labile, protease-sensitive and killed mice within 10 min. The light microscopy of the histopathological studies revealed that the principal organ affected by this toxin was the lung but the liver and kidneys also showed lesions.