Immune response assessment of inactivated Newcastle disease virus liposomal-based vaccine

Abstract

Liposomes were evaluated as an alternative carrier to deliver inactivated Newcastle disease virus (NDV). The ability of a liposomal-based NDV vaccine to activate both cell-mediated immunity (CMI) and humoral immunity against NDV was assessed and compared with conventional NDV vaccines. Birds were assigned to 4 groups and received either no vaccine (control), NDV entrapped into liposomes (LN-NDV), NDV with oil adjuvant (oil-NDV), or live attenuated NDV (live-NDV). All birds were stimulated after 40 days of vaccination i<em>n vivo</em> by an intravenous injection of inactivated NDV crude antigen, which is considered an <em>in vivo</em> NDV-specific stimulation of the chicken immune system. After vaccination and<em> in vivo</em> stimulation, serum samples were collected for NDV-specific antibody response evaluation by a hemagglutination inhibition test (HI) and an enzyme-linked immune sorbent assay (ELISA). The CMI and humoral immunity were evaluated by a measurement of the chicken interferon gamma and specific antibody response in the serum, respectively. Conventional NDV vaccines were able to stimulate a strong humoral and CMI response. Although the newly tested vaccine induced a weak NDV-specific antibody response after vaccination, the response was highly up-regulated, several folds above the protective level, after in vivo stimulation. All NDV vaccine formulas were able to induce a CMI response after vaccination at variable time points. This study revealed that a liposomal NDV-based vaccination in this experimental model tends to induce CMI and can only be beneficial in priming vaccinated birds to promote a strong anti-body response to later NDV exposure.