Viral Enteric Infections

Chicken Astrovirus (CAstV) Molecular Studies Reveal Evidence of Multiple Past Recombination Events in Sequences Originated from Clinical Samples of White Chick Syndrome (WCS) in Western Canada

“…Chicken astrovirus (CAstV) [ 1 ], an enteric, non-enveloped, positive-sense RNA virus has recently emerged as an important poultry pathogen in broiler breeder flocks and their progeny across North America, Brazil, China, and several European countries including Poland, Finland, Norway, and United Kingdom [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Currently, the International Committee of Taxonomy of viruses (ICTV) in the latest 2019 edition has classified CAstV, together with avian nephritis virus (ANV), as members of the Avastrovirus II species within the genus Avastrovirus , in the Astroviridae family [ 10 , 11 ].…”

“…It is worth to note that classification of astroviruses has changed several times since first descriptions were published in the late 1970s to early 1980s [ 9 , 12 , 13 ]. The genetic organization of CAstV is similar to other astroviruses as it is composed of a small, linear RNA of ~7.5 kb in length, coding for three open reading frames (ORF): a non-structural protein (ORF1a), a viral RNA-dependent RNA polymerase (ORF1b, also named RdRp), and a capsid protein (ORF2) [ 3 , 5 , 14 , 15 ]. The capsid protein is highly variable, especially in its 3′ half of the ORF, which forms the external surface of the capsid forming the characteristically five or six-pointed star-like projections of astroviruses [ 16 , 17 , 18 ].…”

“…The capsid protein is highly variable, especially in its 3′ half of the ORF, which forms the external surface of the capsid forming the characteristically five or six-pointed star-like projections of astroviruses [ 16 , 17 , 18 ]. This area interacts with the cell receptor and is exposed to the host immune system [ 3 , 5 , 16 ]. The capsid protein has been divided into two major antigen groups with sub-divisions: Group A divided into three subgroups (i.e., Ai, Aii, and Aiii); and Group B divided into four subgroups (i.e., Bi, Bii, Biii, and Biv) [ 5 ].…”

“…Features of the capsid protein of CAstV are believed to drive the pathogenesis into three syndromes/diseases that are not mutually exclusive: (1) runting-stunting syndrome (RSS) characterized by malabsorption, enteritis, growth problems, and uneven flock performance [ 19 ]; (2) kidney disease and visceral gout characterized by high mortality in young broilers (up to 40%) [ 20 ]; and white chick hatchery disease or white chick syndrome (WCS), a disease characterized by transient increase in mid to late embryo deaths, which causes a reduction in hatchability that can be as low as 4–5% and as high as 68% [ 21 ]. In WCS, some of hatched chicks are considered “white chicks”, a condition characterized by pale plumage, weakness, slow weight gain, poor condition, and eventually death during the first days of life [ 3 , 6 , 21 ]. Lesions can be observed in kidney, liver, feathers, and intestine [ 3 , 5 , 6 , 21 ].…”

Viral metagenomic analysis of chickens with runting-stunting syndrome in the Republic of Korea

“…Infectious intestinal diseases affecting young chickens and turkeys are characterized by mild to severe enteritis and result in considerable economic losses. Viral enteritis increases susceptibility to other diseases, decreases feed conversion efficiency, and prolongs the time to market [1,2]. Runting-stunting syndrome (RSS), also known as malabsorption syndrome, is diagnosed based on clinical signs (diarrhea, dehydration, growth depression, unevenness in size) and histopathological lesions (distension of the crypts of the small intestine, inflammatory cell infiltration in the lamina propria adjacent to affected crypts and necrotic cellular debris in crypts) [3,4].…”