Correlation between cytokine profile,antibody titre and viral load during sub-clinical chicken anaemia virus infection

Abstract

Th e present work was carried out to investigate the correlation between viral load and the cytokine profi le and virus specifi c antibody levels at fi ve day intervals up to 25 days post infection (dpi) in various tissues of chicks infected with chicken infectious anaemia virus (CIAV) at six weeks of age (sub-clinical infection). For determining the viral load in the various tissues, recombinant plasmid VP2-pET32b was prepared and serially diluted tenfold for the generation of a standard curve using real time polymerase chain reaction (PCR). Cytokine fold changes in mRNA levels of IFN-γ, IL-1, IL-2, IL-12 in the spleen and IFN-γ, IL-12 in freshly collected whole blood were determined. Th e results showed that peak viral load occurs between 10-20 days post infection in the lymphoid tissues viz., thymus, spleen, liver, bone marrow, bursa and also blood, being highest in blood followed by thymus. A varied response in the expression levels of individual cytokines was observed during all the intervals post infection. Th e IFN-γ increased two to fi ve fold in blood and spleen while IL-2 decreased in the splenic tissue during the same period. Peak IFN-γ coincided with peak viral load in the spleen at 10 dpi while in blood it peaked earlier at fi ve days post infection and remained high during the peak viral load at 10-20 dpi. Virus specifi c antibodies were signifi cantly higher at 15 dpi and were thereafter found to be strongly associated with viral load regression although higher concentrations of virus remained in the blood and thymic tissues until 25 dpi, indicating a role of other immune components in virus clearance. In conclusion, this study reports a negative correlation of viral load and the progression of the antibody response and IFN-γ cytokine expression in chicks infected with CIAV during their sub-clinical infectious stage. However, cytokine expression from the various individual immune cells like monocytes, heterophils, CD4 + T, CD8 + T cells and others during the pathogenesis of this immunosuppressive poultry pathogen remains to be elucidated.

Immunomodulatory and prophylactic efficacy of herbal extracts against experimentally induced chicken infectious anaemia in chicks: assessing the viral load and cell mediated immunity

“…It was found that the virus concentration in the tissues of positive control birds (group E) was higher than that of herbal treatment groups, with an increase in viral load from 7th to 14th DPI. This pattern of virus Immunomodulatory and prophylactic efficacy of herbal extracts against experimentally induced… 117 multiplication correlates with the observations from other studies in which the virus was inoculated at clinically susceptible age [14,15]. All the four herbal treated groups showed better response against CIAV infection as evidenced by the viral load measurements by qPCR and CMI responses.…”

“…For the quantification of CIAV genome (DNA) in various tissues, isolated DNA samples were used for qRT-PCR analysis in a MX 3000P thermal cycler (Stratagene, California, USA). The forward and reverse primers used for qRT-PCR were VP2F (5 0 -ATGGCAA-GACGAGCTCGC-3 0 ) and VP2R (5 0 -TCACACTATACG TACCGGGG-3 0 ), respectively, that provided an amplicon of 178 bp size [15]. Duplicate sets of each reaction sample were prepared using 10 ll of QuantiFast SYBR Green PCR master mix (Qiagen, Hilden, Germany), 2.5 pmol each of forward and reverse primers, 2 ll of diluted DNA samples and nuclease-free water to make final reaction volume of 20 ll.…”

RETRACTED ARTICLE: Immunosuppressive interactions of viral diseases in poultry

“…In outbreaks of coccidiosis, IBD and bursal atrophy are associated with an increase in lesion severity and mortality and apparent failure of anticoccidial drug treatments (Hoerr, 2010;Kegne and Chanie, 2014). Chicken anaemia virus (CAV, Circoviridae) is vertically transmitted from hens suffering from acute infections during egg production, and is transmitted to the developing embryo (Wani et al, 2014). When the chick hatches, CAV targets haemocytoblasts in the bone marrow and lymphocytes in the thymus, resulting in aplastic anaemia, thrombocytopenia, leukopenia, and thymus depletion in chickens from seven to 14 days of age (Dhama et al, 2008;Umar et al, 2014).…”

“…Chicken infectious anaemia is now largely controlled by ensuring that hens are exposed to CAV prior to the onset of lay. The hen develops antibody to CAV that is transferred to and protects chicks, even though the hen may continue to shed CAV through the reproductive tract (Wani et al, 2014). As a result of broad application of this basic control, blue wing disease is observed less frequently in broiler and layer production today.…”

“…CAV-infected chickens had more severe respiratory reaction to attenuated NDV vaccine, manifested as a reduction in growth. In broiler flocks in Alabama, peak isolation of cycling vaccine strains of IBV coincides with the onset of bursal atrophy attributed to IBDV infection at 20-30 days of age, and thymus atrophy was attributed to subclinical CAV infection that emerged at 30-40 days of age (Dhama et al, 2008;Wani et al, 2014). CAV infection is a risk factor for bacterial infections, due to reduced bactericidal capabilities of macrophages that can last for up to 28 days.…”