The effects of in ovo administration of encapsulated Toll-like receptor 21 ligand as an adjuvant with Marek’s disease vaccine

Abstract

Marek’s Disease Virus (MDV) is the causative agent of a lymphoproliferative disease, Marek’s disease (MD) in chickens. MD is only controlled by mass vaccination; however, immunity induced by MD vaccines is unable to prevent MDV replication and transmission. The herpesvirus of turkey (HVT) vaccine is one of the most widely used MD vaccines in poultry industry. Vaccines can be adjuvanted with Toll-like receptor ligands (TLR-Ls) to enhance their efficacy. In this study, we examined whether combining TLR-Ls with HVT can boost host immunity against MD and improve its efficacy. Results demonstrated that HVT alone or HVT combined with encapsulated CpG-ODN partially protected chickens from tumor incidence and reduced virus replication compared to the control group. However, encapsulated CpG-ODN only moderately, but not significantly, improved HVT efficacy and reduced tumor incidence from 53% to 33%. Further investigation of cytokine gene profiles in spleen and bursa of Fabricius revealed an inverse association between interleukin (IL)-10 and IL-18 expression and protection conferred by different treatments. In addition, the results of this study raise the possibility that interferon (IFN)-β and IFN-γ induced by the treatments may exert anti-viral responses against MDV replication in the bursa of Fabricius at early stage of MDV infection in chickens.

Avian Pattern Recognition Receptor Sensing and Signaling

“…Furthermore, twice administration of encapsulated CpG once in ovo and again on day 14 post-hatch upon MDV challenge (on day 5 post-hatch) resulted in the lowest tumor incidence compared to twice-administered encapsulated LPS or LPS + CpG [193]. Also, in ovo administration of encapsulated synthetic class B CpG ODN 2007 in combination with HVT resulted in significant reduction in very virulent MDV-induced tumor incidence compared to HVT alone [194].…”

“…In chickens, CpG-ODN administration, along with traditional vaccine regimens, was found to boost the vaccine efficacy via adjuvant effects. This adjuvant effect of CpG when delivered via various routes, including in ovo route in embryos, was demonstrated against a wide range of bacterial, viral, and protozoal infections [72,[191][192][193][194][195]. In commercial broilers, in ovo CpG administration via carbon nanotubes or liposomes was found to protect day-old chicks (60% protection) from E. coli or Salmonella typhimurium challenge [196].…”

Immunomodulatory Potential of Tinospora cordifolia and CpG ODN (TLR21 Agonist) against the Very Virulent, Infectious Bursal Disease Virus in SPF Chicks

“…Based on the immunostimulatory properties of TLR agonists, attempts have been made to employ them as an adjuvant with various vaccine antigens. Chicken TLR agonists have been used successfully as vaccine adjuvants [12,46] and prophylactic agents [13,47]. Previous studies already established the role of CpG ODN (TLR21 agonist) as an immunostimulant in chickens leading to increased protection against various pathogens [48,49].…”

In ovo Feeding as a Tool for Improving Performance and Gut Health of Poultry: A Review

“…Encapsulated CpG was used as an adjuvant to check the effects of this in enhancing the efficacy of the herpes virus of turkey (HVT) vaccine for boosting immunity against Marek's disease (MD) ( 68 ). ECpG moderately improved the efficiency of HVT and reduced tumor incidence and MD virus load.…”