TiHo Bibliothek elib - Tierärztliche Hochschule Hannover

107
8 Summary
Jens-Christian Cors (2013):
Investigations of local immunity following vaccination with a recombinant
Herpesvirus of turkeys against Newcastle Disease (rHVT-ND) and a commercial
Newcastle Disease-live vaccine
Newcastle Disease (ND), caused by the Avian Paramyxovirus Serotype 1 (APMV-1),
is responsible for severe damages and economical losses in the poultry industry
worldwide. The development of clinical disease is dependent on the virulence of the
involved AMPV-1 strain, the host species and the immune status of the host.
Symptoms may vary from subclinical infection to peracute death with high mortality in
a flock. Conventional vaccination regimes stimulate local and systemic immunity and
may provide clinical protection in most cases, but viral shedding and spreading of
disease still may occur. Therefore, optimisation of existing vaccination strategies is
required. New generation vaccines like a recombinant herpesvirus of turkeys
expressing the F-protein of APMV-1 are interesting alternatives to conventional
vaccines. If and to what extent they may induce local immunity, and reduce or
prevent viral shedding in the upper respiratory tract is not clear.
In this study, we investigated the effect of rHVT-ND on systemic as well as local
immunity in the upper respiratory tract, the lung and cecal tonsils.
The following parameters were compared between non-vaccinated, rHVT-ND-, live
ND- and rHVT-ND + live ND-vaccinated SPF-chickens (experiment 1) and
commercial broilers (experiment 2): 1) Circulating as well as local B-, T-cell and
macrophage populations in the Harderian gland, in the conjunctiva-associated
lymphoid tissue, in lung and cecal tonsil. 2) Local and systemic antibody production.
3) Tracheal and cloacal virus shedding after a challenge infection.
The study has shown that local immune cell populations were raised slightly in rHVT-
ND groups compared to the control group. CD4+ cells were raised significantly in the
lung on day five post rHVT-ND vaccination in broilers (p