Immunosuppressive Effects of Chicken Infectious Anaemia Virus on T Lymphocyte Populations Using Flow Cytometry and Hematological Parameters During Experimental Subclinical Infection in Chicks

Abstract

| Chicken infectious anaemia virus (CIAV) is an economically important pathogen affect-ing poultry industry worldwide, and renders birds susceptible to secondary infections. The present study was designed to investigate the systemic immunosuppressive effects of CIAV on T lymphocytes bearing CD4 and CD8 receptors using flow cytometry and hematological parameters during experimental subclinical infection in chicks. Forty specific pathogen free (SPF) chicks of 6 weeks of age were randomly and equally divided into two groups. Infected group received 10 4.5 TCID 50 of CIAV while control chicks were mock inoculated. All the chicks were regularly monitored for clinical signs, hematology parameters and CD4 + and CD8 + cell populations in spleen and blood. The experimental CIAV infection was confirmed by PCR testing of the tissue samples of experimental chicks, using VP2 gene specific primers, which yielded an expected amplicon size of 651 base pairs. The analysis of the hematological parameters showed significant decline in hematocrit value (PCV), total leukocyte count (TLC) and peripheral lymphocyte count (PLC) after 15 days post infection (dpi) but with no clinical signs of CIA. Flow cytometric analysis revealed that the percentage of CD4 + CD8 -and CD4 -CD8 + T cells significantly decreased in the virus infected chicks at 15 dpi both in the spleen and blood (p<0.05). The results supported the fact that subclinical CIAV infections are also immunodepressive in nature; the virus replicates in primary lymphoid tissues and induces immunosuppression by decreasing both CD4 + and CD8 + T cells in chicks.

RETRACTED ARTICLE: Immunosuppressive interactions of viral diseases in poultry

“…CAV infects cells bearing class II antigens in bone marrow and T-helper lymphocytes in thymus. An MHC effect on resistance to CAV infection was not detected, but induced mutations on CAV had an effect on virus replication, cytopathogenicity and down regulation of MHC class I genes in infected cells (Joiner et al, 2005;Umar et al, 2014;Wani et al, 2015).…”

“…Thus, chickens with declining maternal immunity become susceptible to CAV at 20-30 days of age, and may be younger if maternal antibody protection is marginal. The thymus depletion is a subclinical event, but broilers with CAV-depleted thymuses develop secondary infections, including gangrenous dermatitis, coccidiosis, and viral and bacterial infections of the respiratory tract (Wani et al, 2015). Chickens co-infected with IBDV have increased susceptibility to CAV infection at older ages, are more likely to develop contact infections by CAV, have higher mortality rates and prolonged acute phase prior to recovery or mortality (Umar et al, 2014).…”

“…Both are increased by subclinical infections with either IBDV or CAV (Lamont et al, 2014;Wani et al, 2015), and could be assessed following a brief laboratory challenge by inactivated Newcastle virus (Hoerr, 2010). Interleukin-2 has been proposed as a general measure of cell mediated competency in the chicken's intestine.…”

“…The pathogenesis of MD can be enhanced or inhibited by CAV, depending on the titre of the challenge dose of MDV. Early CAV infection results in decreased protection from vaccination for either ND or laryngotracheitis, and combined CAV and IBDV challenge reduced vaccine protection for fowl pox (Hoerr, 2010;Wani et al, 2015). CAV-infected chickens had more severe respiratory reaction to attenuated NDV vaccine, manifested as a reduction in growth.…”

Immunomodulatory and Protective Effects of a Polyherbal Formulation (Immon) Against Infectious Anemia Virus Infection in Broiler

“…CIAV causes suppression of differentiation and proliferation of haemopoietic precursor cells, leading to anemia and panleukopenia. Repopulation of the bone marrow with proerythroblasts and promyelocytes and recovery of haematopoietic activity (erythropoiesis) and lymphocyte repopulation occur during recovery phase (Taniguchi et al, 1982;Liu et al, 1997;Wani et al, 2015). The virus plays a key role in the etiology of several multifactorial diseases like haemorrhagic syndrome, haemorrhagic anemia syndrome, infectious/aplastic anaemia, anaemia-dermatitis syndrome, gangrenous dermatitis and blue wing diseases (Pope, 1991;Toro et al, 2000;Hagood et al, 2000).…”