Depression of Vaccinal Immunity to Marek’s Disease by Infection with Chicken Infectious Anemia Virus

Abstract

Marek’s disease (MD) has been occurring with increasing frequency in chickens in recent years. To our knowledge, however, there has been no report of the very virulent plus (vv+) MD virus (MDV) field isolate in China. Studies have shown that dual infection with immunosuppressive viruses such as chicken infectious anemia virus (CIAV) occurs frequently in chickens developing MD. In this study, we performed a designed set of in vivo experiments, which comprised five different groups of chickens, including the group of CVI988/Rispens-vaccinated chickens, the groups of CVI988/Rispens-vaccinated chickens infected with MDV or CIAV or both viruses (MDV and CIAV), and the group of MDV-challenged chickens. The effects of CIAV dual infection on the immunization of commercial MDV vaccine CVI988/Rispens were evaluated. The results show that infection of the SD15 strain of CIAV significantly reduced the weight and antibody titers to avian influenza virus (AIV)/Newcastle disease virus (NDV) inactivated vaccines of chickens immunized with the CVI988/Rispens, and resulted in the atrophy of thymus/bursa and the enlargement of spleen. The CVI988/Rispens vaccination conferred good immune protection for chickens challenged with 2000 PFU of the GX0101 strain of MDV. However, dual infection with SD15 significantly reduced the body weight, antibody titers induced by AIV/NDV inactivated vaccines and protective index of CVI988/Rispens, and resulted in the aggravation of the immunosuppression, mortality, and viremia of GX0101 in CVI988/Rispens-immunized/GX0101-challenged chickens. Overall, CIAV infection significantly reduced the protective effects of the CVI988/Rispens vaccine against MDV, implying that concurrent infection with CIAV may be a major contributor in the frequent attacks of MD in China in recent years.

Development and Application of an MRT-qPCR Assay for Detecting Coinfection of Six Vertically Transmitted or Immunosuppressive Avian Viruses

“…These avian viruses can cause both single-virus infection and multiple-virus infection. Infections with multiple viruses complicate the pathogenesis, identification, prevention, and control of these pathogens (Li et al, 2017;Sun et al, 2017;Zhang et al, 2017;Cong et al, 2018). A rapid and efficient detection method is urgently needed to investigate the infection condition of these avian viruses.…”

Increased Horizontal Transmission of Recombinant Marek’s Disease Virus Due to Reticuloendotheliosis Virus Long Terminal Repeat Is the Major Competitive Advantage of the Virus Being a Prevalent Strain

“…Marek's disease has been prevalent among Chinese chicken flocks over the last 20 years (Cui et al, 2016;He et al, 2018). The incidence of MDV was highly heterogeneous in different regions and flocks because of the various geographical environments, different feeding patterns, and varieties of chicken breeds in China (Zhang et al, 2017). REV LTR could be integrated into the MDV genome at different sites following continuous passages of MDV on REV-infected CEF cells (Isfort et al, 1992).…”

Biotic concerns in generating molecular diagnosis matrixes for 4 avian viruses with emphasis on Marek’s disease virus

“…The two viruses MDV and CAV cause persistent infections and immunosuppression and synergize in mortality in experimental infection trials and in commercial flocks (Zhang et al, 2017). The pathogenicity of the dual MDV and CAV infection are demonstrated by a variety of symptoms (Haridy et al, 2012) and co-infection of commercial flocks is mostly subclinical, and not acute.…”