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. Stress or non-stressed SH-infected birds had high levels of norepinephrine on ED21. On ED21, an increased percentage and number of SH were found in birds of the PCS group. On ED7, a decrease in macrophages presenting MHCII, CD8(+) and CD8(+) γδ cells was observed in the chickens of the CS group. Decrease was observed in CD3(+) cells in the birds of the PCS group and increase in macrophages presenting MHCII cells and of the CD4(+)/CD8(+) ratio in chickens of the CS group on ED21. There was a decrease in CD8(+) γδ cells in birds of the CS group on ED21 and in the CD3(+) and CD8(+)cell numbers in chickens of the PCS group on ED21. Our results suggest that cold stress applied to chickens in the first 7 days of life increases both the hypothalamus pituitary adrenal axis and the sympathetic nervous system activities, leading to long-term immune cell dysfunction, thus allowing increased SH invasion and persistence within the birds' body.

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. As part of an ILT control program implemented in a region of commercial layer production, samples of conjunctiva, trachea, and trigeminal ganglia were collected from chickens in a vaccinated and quarantined region over a period of 8 years after initiation of vaccination. To determine the origin of new ILT outbreaks in unvaccinated regions, samples collected from ill chickens were also analyzed. Chicken embryo origin (CEO) vaccine viruses and the Bastos field strain were detected circulating in healthy chickens in the vaccinated region. CEO strains and field viruses molecularly related to the Bastos strain were also detected outside of the quarantined region in chickens showing clinical signs of ILT. This study reveals the persistence and circulation of a wild field strain, despite the intensive use of tissue culture origin (TCO) and CEO vaccines in a quarantined region. Spreading of CEO viruses to unvaccinated regions and the capacity of this virus to establish latent infections and cause severe outbreaks were also observed.

Detection of chicken anemia virus and infectious bursal disease virus co-infection in broilers / Detecção do virus da anemia das galinhas em coinfecção com o vírus doença infecciosa bursal em frangos

This survey aimed to investigate chicken anemia virus (CAV) in broilers flocks experimenting retarded growth and increasing mortality since the fourth day of age. Clinically, chickens presented depression, paleness, depigmentation and retarded growth. At necropsy, chickens presented CAV-compatible lesions. Samples from liver, spleen and thymus were tested by PCR for a 675-bp fragment of the CAV VP-1 gene, and all tested samples were positive. Serological and molecular techniques did not detect other pathogens, such as adenovirus, reovirus, astrovirus, infectious bursal disease and avian infectious bronchitis virus. These results showed that chicken anemia virus (CAV) may occur since the first few days of life in broilers - a fact not as yet reported -, associated with high pathogenic Infectious Bursal Disease Virus (IBDV) vaccine strain may induce a persistent growth retarded for several weeks in broilers.(AU)

Este estudo investigou a manifestação do vírus da Anemia Infecciosa das Aves (VAIA) em lotes de frangos que apresentavam retardo no crescimento e aumento da mortalidade observado a partir do quarto dia de idade. Clinicamente, as aves apresentavam depresão, palidez, despigmentação e retardo de crescimento. À necropsia, as aves apresentavam lesões compatíveis com a infecção pelo vírus da Anemia infecciosa das aves (VAIA). Amostras de fígado, baço e timo foram examinadas por PCR que amplifica um frangmento de 675 pb do gene VP-1 do VAIA. Todos os órgãos examinados foram positivos para o vírus da Anemia Infecciosa das Aves. Os demais patógenos, como adenovírus, reovírus, astrovírus, vírus da doença infecciosa bursal e coronavírus aviário não foram detectados pelas diferentes técnicas laboratoriais, como sorologia, PCR ou PAGE. Os resultados mostraram que o vírus da Anemia Infecciosa das Aves (VAIA) pode manifestar-se clinicamente nos primeiros dias de vida dos frangos um fato ainda não reportado associado ao vírus vacinal da doença infecciosa bursal (DIB) cepa forte pode induzir um persistente retardo de crescimento, por várias semanas, em frangos.(AU)

Detection of chicken anemia virus and infectious bursal disease virus co-infection in broilers / Detecção do virus da anemia das galinhas em coinfecção com o vírus doença infecciosa bursal em frangos

This survey aimed to investigate chicken anemia virus (CAV) in broilers flocks experimenting retarded growth and increasing mortality since the fourth day of age. Clinically, chickens presented depression, paleness, depigmentation and retarded growth. At necropsy, chickens presented CAV-compatible lesions. Samples from liver, spleen and thymus were tested by PCR for a 675-bp fragment of the CAV VP-1 gene, and all tested samples were positive. Serological and molecular techniques did not detect other pathogens, such as adenovirus, reovirus, astrovirus, infectious bursal disease and avian infectious bronchitis virus. These results showed that chicken anemia virus (CAV) may occur since the first few days of life in broilers - a fact not as yet reported -, associated with high pathogenic Infectious Bursal Disease Virus (IBDV) vaccine strain may induce a persistent growth retarded for several weeks in broilers.

Este estudo investigou a manifestação do vírus da Anemia Infecciosa das Aves (VAIA) em lotes de frangos que apresentavam retardo no crescimento e aumento da mortalidade observado a partir do quarto dia de idade. Clinicamente, as aves apresentavam depresão, palidez, despigmentação e retardo de crescimento. À necropsia, as aves apresentavam lesões compatíveis com a infecção pelo vírus da Anemia infecciosa das aves (VAIA). Amostras de fígado, baço e timo foram examinadas por PCR que amplifica um frangmento de 675 pb do gene VP-1 do VAIA. Todos os órgãos examinados foram positivos para o vírus da Anemia Infecciosa das Aves. Os demais patógenos, como adenovírus, reovírus, astrovírus, vírus da doença infecciosa bursal e coronavírus aviário não foram detectados pelas diferentes técnicas laboratoriais, como sorologia, PCR ou PAGE. Os resultados mostraram que o vírus da Anemia Infecciosa das Aves (VAIA) pode manifestar-se clinicamente nos primeiros dias de vida dos frangos – um fato ainda não reportado – associado ao vírus vacinal da doença infecciosa bursal (DIB) cepa forte pode induzir um persistente retardo de crescimento, por várias semanas, em frangos.

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. The recombinant expression construct (pTrc-VP3) was identified by PCR and sequencing analysis. Expression of VP3 protein with a molecular mass of approximately 21kDa was confirmed by Western blotting analysis with CAV-specific antibodies. The in vitro expressed VP3 protein was purified to near homogeneity by elution from the gel, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The purified VP3 protein was recognized by CAV antibodies in a Western blotting assay. This finding indicates that recombinant VP3 expressed in the pTrcHis2 vector system can be used as antigen to detect anti-CAV antibodies.