Infection dynamics of a chicken T-cell line by different pathotypes of marek's disease virus (MDV)
Date
2022
Authors
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Publisher
University of Delaware
Abstract
Marek’s disease virus (MDV) is an acute-transforming Alphaherpesvirus of chickens that causes paralysis and T-cell lymphoma formation. Despite the ability of vaccines to reduce the impact of Marek’s disease in poultry production, vaccinated chickens support superinfection and transmission of virulent field strains. Considering that MDV ecology has been manipulated in poultry production by the concentration of genetically-uniform, imperfectly vaccinated hosts of ever-decreasing lifespan; the classic model of MDV’s early lytic phase, latency, and reactivation, appear to have been under selective pressures. To aid in our understanding of this evolution of virulence, we seek to compare MDV uptake into susceptible cells, specifically T cells, amongst different pathotypes. We sought to quantify these differences in MDV genome uptake and replication by performing qPCR analysis of CU91s (a REV- transformed T cell line of chickens) that have been infected with different strains of MDV (CU2 mild strain; M173 and 571 virulent strains; RB-1B, Md5, and 1137 very virulent strains; and N strain, TK1A, and TK2A very virulent + strains). Recombinant viruses (pRB-1B, GFP-2a-Meq, UL49-2a-RFP; very virulent strain), (pCVI988-GFP- 2a-Meq, UL49-2a-RFP; virulent strain), and (p686-GFP-2a-Meq, UL49-2a-RFP; very virulent + strain), which have fluorescent proteins defining stages of lytic infections helped elucidate how difference virulence levels affect MDV uptake and subsequent gene expression. The qPCR analyses of the non-fluorescent pathotypes showed that there was no marked difference between pathotypes as it relates to viral genome copy number per 1000 cells during the initial stages of infection. Conversely, flow cytometric analyses of the recombinant viruses did exhibit changes amongst pathotypes, with the more virulent strains exhibiting higher increases in fluorescence over time compared to the less virulent strains; suggesting that gene expression differs between different MDV pathotypes. Overall, it was found that there was no significant effect on MDV uptake and replication in these T-cells with increasing virulence; however, there were marked differences in gene expression amongst the different pathotypes, with MDVs of higher virulence exhibiting higher levels of gene expression.
Description
Keywords
Marek's Disease Virus, Pathotype, Infection dynamics