Relationship between Marek's disease and coccidiosis. II. The effect of Marek's disease on the susceptibility of chickens to coccidial infection

Biggs, P. M.; Long, P. L.; Kenzy, S. G.; Rootes, D. G.

doi:10.1136/vr.83.12.284

Cited by 44 publications

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“…This is the first report of increased susceptibility to secondary infection with E. coli as a result of concurrent MDV infection. Increased susceptibility following MDV challenge has also been reported for coccidial and cryptosporidial infections (Biggs et al, 1968;Abbassi et al, 1999Abbassi et al, , 2000. It is important to note that the greatest reduction in lymphocyte counts occurred in experiment 2 at day 35, a week after coinfection with E. coli.…”

Section: Discussionmentioning

confidence: 99%

“…However, functional deficiencies of effector cells such as downregulation of expression of CD8 and Major Histocompatibility Complex (MHC) molecules may also be important (Morimura et al, 1995(Morimura et al, , 1996. Consequences of this immunosuppression in terms of reduced resistance to concurrent infection have been reported for coccidiosis and renal cryptosporidiosis (Biggs et al, 1968;Abbassi et al, 1999Abbassi et al, , 2000, but the extent of immunosuppression varies according to several host resistance factors and the pathotype of virus (Calnek et al, 1998;Baigent & Davison, 1999).…”

Section: Introductionmentioning

confidence: 99%

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Immunosuppressive effects of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) in broiler chickens and the protective effect of HVT vaccination against MDV challenge

et al. 2002

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Immunosuppressive effects of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) in broiler chickens and the protective effect of HVT vaccination against MDV challenge

et al. 2002

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“…We showed that CD8 was down-regulated at the transcriptional level during MDV infection (Figs 3 and 4). It is well known that MDV can cause a functional deficiency of CTL, for example delayed rejection of Rous sarcomas or MD transplantable tumour cells (Calnek et al, 1975), increased susceptibility to coccidiosis (Biggs et al, 1968) and absence of specific cytotoxic activities against MD tumour cells (Schat et al, 1982;Powell et al, 1983). Down-regulation of CD8, therefore, may be important for the immunosuppression of T cells.…”

Section: T Morimura and Othersmentioning

confidence: 99%

“…At the same time, MDV causes secondary immunosuppression, which is characterized by unresponsiveness to mitogen stimulation (Theis et al, 1975), delayed rejection of Rous sarcomas or MD transplantable tumour cells (Calnek et al, 1975), and increased susceptibility to coccidiosis (Biggs et al, 1968). Interestingly, cytotoxic T lymphocytes (CTL) against syngenic MD tumour cell lines, which had been thought to be important for tumour inhibition, were not detected in chickens infected with MDV (Schat et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Immunomodulation of peripheral T cells in chickens infected with Marek's disease virus: involvement in immunosuppression

Morimura

Hattori

Ohashi

et al. 1995

Journal of General Virology

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Marek's disease virus (MDV) causes T cell immunosuppression in chickens during latent infection. Morphological changes specific to apoptosis were demonstrated in peripheral blood mononuclear cells (PBMC) of MDV-infected chickens at 2-3 weeks post-inoculation (p,i.). Analysis of DNA fragmentation in T cell subsets in the peripheral blood revealed that CD4 + T cells but not CD8 + T cells underwent apoptosis after MDV infection. The proportion of CD4 + T cells, but not that of CD8 + T cells, in the peripheral blood expanded transiently at 16 days p.i., and rapidly decreased 1 week later. The decrease in CD4 + T cells might be mediated by apoptosis, because a rapid reduction in CD4 + T cells was observed when these cells underwent apoptosis.Analysis of the T cell-receptor (TCR) repertoire of the peripheral blood showed that Vfll but not Vfl2-~tfl TCRbearing cells expanded at 16 days p.i., when the transient expansion of the CD4 ÷ T cell population was observed in these chickens. Flow cytometric profiles also showed that the expression of CD8 was down-regulated after infection with MDV, but there was no difference in the expression level of CD4 molecules between normal and infected chickens. Northern blot analysis indicated that the down-regulation of CD8 occurred at the transcriptional level. These results suggest that both apoptosis of CD4 ÷ T cells and down-regulation of CD8 molecules could contribute to the immunosuppression caused by MDV.

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“…The economic damage of MD is probably even greater because immunosuppression induced by the MD virus reduces resistance to other pathogens, which can lead to symptoms in young, market-weight broilers (Biggs et al, 1968; Abbassi et al, 1999), and lowers feed efficiency and other production traits (Groves, 1995; Islam et al, 2002). Vaccines have been produced that initially were effective in reducing MD incidence (Witter, 1985), but MD virus strains have evolved to the point that commercial vaccines are no longer fully protective.…”

Section: Introductionmentioning

confidence: 99%

Mapping quantitative trait loci for economic traits in chickens

McElroy

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All rights reserved. INFORMATION TO USERSThe quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Table 1 Table 2 CHAPTER 2B Table 1 Table 2 Table 3 Significant QTL detected at the 5% chromosome-wise 58Level Table 1 False positive rates for the linear regression and Cox's 117proportional hazards models ABSTRACTIdentification of genomic regions harboring genes affecting economic traits is the primary step for the improvement of agricultural species through marker-assisted selection. Many important traits are difficult and expensive to measure, and, thus, selection can be improved by selecting directly upon genomic regions affecting these traits (QTL). White meat percentage (WM%) and Marek's disease (MD) resistance are examples of important traits in commercial chickens. One objective of the research presented herein was to identify QTL affecting WM%, other growth-related traits, and MD resistance. Another objective was to compare statistical models for identifying these QTL. Data (phenotypes and genetic markers) on an F2 broiler (meat-type chicken) cross were analyzed using half-sib, line cross, combined, and parent of origin models to identify QTL affecting WM% and other growth related traits. Sixty-eight QTL were identified at the 5% chromosome-wise level, including six QTL affecting WM% and 20 putative imprinted QTL. The use of multiple segregation and expression models proved to be beneficial for identifying QTL. A commercial egg-layer backcross was used to identify QTL affecting MD resistance based on marker genotypes of long and short survivors (selective genotyping). Seventeen markers associated with MD survival were identified at P < 0.10 using linear regression (LR) and Cox proportional hazards (CPH) models. Using simulated data reflecting the MD virus-challenged population, analyses using LR, CPH, and Weibull models were compared. Little difference in power was found between the CPH and the LR model when few individuals survived to the end of the experimental period (low censoring) and when all or selected individuals were genotyped. The simulated data did not follow a Weibull distribution, and thus the Weibull model generally resulted in less power than the other two models. The LR model was recommended for analyzing survival data when the amount of censoring is low because of the ease of implementation of the model and interpretation of estimates. Including nongenotyped individuals in the selective genotyping analysis increased power, but resulted in LR having an inflated false positive rate. The QTL identified in this research can be an integral step for the improvement...

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Relationship between Marek's disease and coccidiosis. II. The effect of Marek's disease on the susceptibility of chickens to coccidial infection

Cited by 44 publications

References 0 publications

Immunosuppressive effects of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) in broiler chickens and the protective effect of HVT vaccination against MDV challenge

Immunosuppressive effects of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) in broiler chickens and the protective effect of HVT vaccination against MDV challenge

Immunomodulation of peripheral T cells in chickens infected with Marek's disease virus: involvement in immunosuppression

Mapping quantitative trait loci for economic traits in chickens

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