Viral load in 1-day-old and 6-week-old chickens infected with chicken anaemia virus by the intraocular route

• Published in: Avian pathology 2006-12, Vol.35 (6), p.471-474
• Main Authors: Kaffashi, A, Noormohammadi, A.H, Allott, M.L, Browning, G.F
• Format: Article
• Language: English
• Subjects: Aging; anemia (disease); Animals; Body Weight; Chicken anemia virus; Chicken anemia virus - isolation & purification; Chickens; chicks; Circoviridae Infections - blood; Circoviridae Infections - virology; disease resistance; eyes; immune response; in vivo studies; infection; Infections; liver; Liver - virology; old animals; pathogenicity; polymerase chain reaction; Poultry; poultry diseases; signs and symptoms (animals and humans); spleen; Spleen - virology; Studies; thymus gland; Thymus Gland - virology; viral diseases of animals and humans; Viral Load - veterinary; virus replication; Viruses
• ISSN: 0307-9457; 1465-3338
• DOI: 10.1080/03079450601028837

Although the effects of chicken anaemia virus (CAV) infection have frequently been investigated in young chickens, there have been few studies of the pathogenesis of CAV infection in older birds. The aim of the work reported here was to study viral loads in 6-week-old chickens and to compare these with those seen in younger birds. Specific pathogen free chickens were inoculated at 1 day or at 6 weeks of age with 10 4 median tissue culture infective doses of CAV by the intraocular route. Chicks infected when 1 day old were euthanized at day 14, 18 or 22 post inoculation (p.i.), and those infected when 6 weeks old at day 16, 18 or 20 p.i. Their body and thymus weights were determined and samples were collected from their spleen, liver and thymus. A quantitative polymerase chain reaction assay was developed and used to determine the number of viral genome copies in the tissue samples. In both age groups, viral genome concentrations increased in all organs up to day 18 p.i. and reached a peak in the spleen and liver at day 18 p.i. The peak viral concentrations in the thymus were detected at day 18 in the younger birds and at day 20 p.i. in older chickens. These studies have shown that exposure to CAV in older birds leads to similar levels of active viral replication to those seen in younger birds, and may result in subclinical infections in older birds with the potential to increase susceptibility to other infectious agents. Bien que les effets de l'infection par le virus de l'anémie du poulet (CAV) ont souvent été investigués chez des jeunes poulets, il y a peu d'études de pathogénie de l'infection par le CAV chez des poulets plus âgés. Le but de ce travail a été d'étudier les charges virales chez des poulets âgés de six semaines et de les comparer à celles d'animaux plus jeunes. Des poulets, exempts de microorganismes pathogènes spécifiés, ont été inoculés aux âges d'un jour ou de six semaines avec 10 4 DICC50 de CAV administré par instillation oculaire. Les poussins qui ont été infectés à un jour, ont été euthanasiés à 14, 18 ou 22 jours après l'inoculation (p.i.) et ceux infectés à l'âge de six semaines l'ont été à 16, 18 or 20 jours p.i.. Les poids du corps et du thymus ont été déterminés et des échantillons de rate, de foie et de thymus ont été prélevés. Une réaction de polymérisation en chaîne quantitative a été développée et utilisée pour déterminer le nombre de copies de génome viral dans les échantillons de tissu. Dans les deux groupes d'âges différe