An Attenuated Duck Plague Virus (DPV) Vaccine Induces both Systemic and Mucosal Immune Responses To Protect Ducks against Virulent DPV Infection

Abstract

c Duck plague (DP) is a severe disease caused by DP virus (DPV). Control of the disease is recognized as one of the biggest challenges in avian medicine. Vaccination is an efficient way to control DPV, and an attenuated vaccine is the main routine vaccine. The attenuated DPV vaccine strain CHa is a modified live vaccine, but the systemic and mucosal immune responses induced by this vaccine have been poorly understood. In this study, the immunogenicity and efficacy of the vaccine were evaluated after subcutaneous immunization of ducks. CD4؉ and CD8 ؉ T cells were counted by flow cytometry, and humoral and mucosal Ig antibodies were analyzed by enzyme-linked immunosorbent assay (ELISA). The results showed that high levels of T cells and Ig antibodies were present postimmunization and that there were more CD4 ؉ T cells than CD8 ؉ T cells. Titers of humoral IgG were higher than those of humoral IgA. Local IgA was found in each sample, whereas local IgG was found only in the spleen, thymus, bursa of Fabricius, harderian gland, liver, bile, and lung. In a protection assay, the attenuated DPV vaccine completely protected ducks against 1,000 50% lethal doses (LD 50 ) of the lethal DPV strain CHv via oral infection. These data suggest that this subcutaneous vaccine elicits sufficient systemic and mucosal immune responses against lethal DPV challenge to be protective in ducks. This study provides broad insights into understanding the immune responses to the attenuated DPV vaccine strain CHa through subcutaneous immunization in ducks.

Duck virus enteritis (duck plague) – a comprehensive update

“…Post-immunization humoral level of immunity was assessed by measuring the titers of IgG and IgM using ELISA with the number of CD4 (+) T cells was found increased in contrast to the CD8(+) T cells through flow cytometry after immunization. These results support the subcutaneous route of administration for delivering attenuated vaccines (Huang et al 2014). Hence adopting an appropriate route of vaccination is an essential factor to elicit desired protective immunity.…”

“…Live attenuated vaccines are considered most effective against DPV hence it is of foremost importance to maintain the vaccine at optimum physical and physiological conditions of temperature, salt and pH to prevent any loss in the activity of vaccine candidate molecule (Makhija & Kumar 2016). The vaccinated ducks could excrete the virus thus demands revaccination of the entire flock (Huang et al 2014).…”

Role of Emergency Vaccination as a Trial to Control DEV Infection in Muscovy Ducklings

“…Through clinical and pathological pictures that were examined under the experimental infection, infected-emergency vaccinated groups had clinico-pathological pictures lower than in infected-non-vaccinated group especially that vaccinated via subcutaneous route. This explained by Huang et al [14] who demonstrated that subcutaneous administration of the attenuated DEV vaccine could produce efficient humoral, cellular, and mucosal immune responses against DEV challenge. Also, Xiaoyan et al [35] proved that oral immunization with live attenuated DEV vaccine is effective in inducing mucosal immunity that is important in protecting animals from intestinal infections.…”

“…Immunization of ducks is an efficient tool to prevent DEV infection [13,14]. Live attenuated and/or an inactivated vaccines induced effective immune response in birds [12].…”

“…Live attenuated and/or an inactivated vaccines induced effective immune response in birds [12]. DEV attenuated live vaccine has been used extensively worldwide and provides a good protection [14]. However, Dardiri [15] found that the high level of serum antibody does not prevent virus shedding from the cloaca or esophagus of infected waterfowl.…”