Localization of Avian Leukosis Virus Subgroup J in Naturally Infected Chickens by RNA In Situ Hybridization

Abstract

Abstract. The novel subgroup J of avian leukosis virus (ALV-J) has emerged as a significant cause of myeloid neoplasia and weight suppression in broiler chickens. We investigated viral tropism using RNA in situ hybridization (ISH) in naturally infected chickens. Formalin-fixed tissues were collected from 12-day-old embryos (seven infected, two control) and from 0-week-old (four infected, one control), 3-week-old (five infected, one control), 6-week-old (five infected, one control), and 9-week-old (10 infected, two control) chickens naturally infected with ALV-J in ovo. A 636-base antisense riboprobe complementary to the 3Ј and 5Ј ends of the pol and env viral genes, respectively, was constructed. Strong positive staining was present in cardiac myocytes, Purkinje fibers, vascular and pulmonary smooth muscle, renal glomeruli, distal tubules, and pituitary glands. Light staining was present in gastrointestinal smooth muscle, thyroid and adrenal glands, and follicular medullae in the cloacal bursa. Staining was not present in any hematopoietic precursors. Tissues from newly hatched chicks exhibited the strongest and most consistent staining, whereas staining in embryos was minimal. RNA ISH confirmed the presence of ALV-J-specific nucleic acid within cytoplasmic inclusions in cardiac myocytes, Purkinje fibers, pituitary glands, and renal glomeruli. Viral tropism for cardiac myocytes and Purkinje fibers may relate pathogenetically to the cardiomyopathy and congestive heart failure described in index chicken flocks infected with ALV-J. Viral tropism for endocrine organs may relate pathogenetically to the weight suppression associated with infection.

Distribution of viral antigen gp85 and provirus in various tissues from commercial meat-type and experimental White Leghorn Line 0 chickens with different subgroup J avian leukosis virus infection profiles

“…The data also show that using primer set H5/H7, but not sets 6J/Smith2, F5/ Smith2 or H5/R11, proviral DNA was detected in tissues collected from non-viraemic seroconverted chickens. The tissue distribution of ALV J antigen in viraemic chickens was in agreement with previous studies (Dougherty & Di Stefano, 1967;Arshad et al, 1997;Gharaibeh et al, 2001;Stedman et al, 2001;Williams et al, 2004). All previously reported studies used tissues from viraemic chickens that had extensive distribution of gp85, similar to tV'A(, ntV'A( and V'A' chickens used in the present study.…”

“…Several studies on ALV tissue tropism were conducted to demonstrate the presence of virus in various tissues of the chicken using electron microscopy (Dougherty & Di Stefano, 1967;Di Stefano & Dougherty, 1969;Di Stefano et al, 1973;Gilka & Spencer, 1985), immunohistochemistry (IHC) (Dougherty et al, 1972;Gilka & Spencer, 1984;Arshad et al, 1997;Gharaibeh et al, 2001;Williams et al, 2004) and molecular methods (Robinson et al, 1993;Arshad et al, 1999;Stedman et al, 2001). All of these previous studies demonstrated ALV protein or nucleic acid in chickens that were inoculated with ALV either in ovo or on day of hatch; in most cases, sampling coincided with the viraemic phase of the infection.…”

Na + /H + exchanger type 1 is a receptor for pathogenic subgroup J avian leukosis virus

“…High levels of viral RNA were seen in the heart, kidney, pituitary, adrenal, and thyroid glands. However, in both of these studies, no infection was seen in the bone marrow and only cells with dendritic morphology were stained in the bursa and thymus (33). It is possible that NHE-1 is abundantly expressed on a small subset of differentiating myeloid cells, causing them to be more effectively targeted by ALV-J, but the low abundance or distribution of these cells does not allow detection during in situ analysis.…”

“…chNHE1 probably carries out housekeeping functions similar to mammalian NHE1, and its expression is likely required in all lines of chickens, possibly accounting for the broad susceptibility of chickens to ALV-J. Analysis of ALV-J tropism in infected chickens by in situ hybridization demonstrates infection of many tissues (33,34) consistent with the presumed extensive expression of chNHE1. High levels of viral RNA were seen in the heart, kidney, pituitary, adrenal, and thyroid glands.…”

Histopathological and ultrastructural characteristics of myeloid leukosis in broiler chicken

“…The disease is one of the main causes of mortality in chickens. Since ALV-J was firstly reported in the United Kingdom, in 1989 (Payne et al, 1991), there are important studies on the molecular aspects of this virus (Venugopal, 1999;Silva et al, 2000), the pathogenesis of this disease (Stedman et al, 2001), diagnostic methods (Fadly, 2000;Qin et al, 2001) and mode of transmission of viruses (Witter and Fadly, 2001). …”