The determination of those polypeptides of Newcastle disease virus involved in protection

Abstract EN

The objective of this study was to identify those polypeptides of Newcastle disease virus (NDV) that are involved in protection.

Six groups of 3-week old chickens were injected with either the Hemagglutinin-neuraminidase protein(HN), Fusion protein(F), Nucleoprotein(NP), Matrix protein(M), UV-inactivated NDV(UV-NDV) (positive control) or saline (negative control).

Blood samples were collected weekly for evaluating the humoral and cellular immune responses using Western blot, ELISA and a MTT lymphoblastogensis microassay.

Protective immunity was determined by clinical disease and virus shedding following challenge with NDV strain Texas GB.

Antibodies to UV-NDV, HN, F and NP were detected at 3 weeks post-vaccination by Western blot and ELISA.

Lymphocytes from all vaccinated birds, with the exception of the group vaccinated with the M polypeptide, demonstrated specific increased blastogenesis when stimulated with UV-NDV.

The maximum stimulation occurred with the group vaccinated with the HN polypeptide.

All vaccinated groups other than the UV-NDV, were susceptible to NDV infection and clinical disease when challenged.

It is hypothesized that conformational changes in polypeptides during isolation and purification may have altered the protective epitopes.