Effects of Cytosine-phosphate-Guanosine Oligodeoxynucleotides (CpG-ODN) on vaccination and immunization of neonatal chickens

by Barri, Adriana

The objective of this investigation was to evaluate the effects of administering

CpG-ODN to commercial strain chickens as a potential adjuvant to vaccination against

Salmonella, Eimeria spp., and Newcastle disease virus, or immunization to bovine

serum albumin (BSA). During Experiment 1, which evaluated the dual application of

CpG-ODN and a Newcastle disease virus vaccine, in the first of three replicate trials,

on day 28 of the experiment, animals in the Vaccine + CpG 1& 14 experimental group

were observed to have the highest levels of (p<0.05) anti-NDV IgG in serum. These

levels were elevated above levels in animals from all other experimental groups. This

suggestion for an adjuvant effect associated with CpG-ODN administration was not

supported in the remaining two trials of experiment 1.

Experiment 2 evaluated the potential for CpG-ODN to adjuvant a commercial

live oocyst coccidial vaccine when applied by an oral route to neonatal broiler

chickens. Overall, when body weight gain during challenge, development of intestinal

lesions, and anti-Eimeria IgG levels were evaluated, vaccine administration alone was

demonstrated to provide the best measure of protection among animals in all

experimental groups, including those receiving either CpG-ODN or Non CpG-ODN.

Experiment 3 investigated the simultaneous administration of CpG-ODN or

Non-CpG ODN and a commercially acquired Salmonella typhimurium vaccine to

SCWL chickens. Similar to experiments 1 and 2, antigen specific IgG responses in

serum and indices of protection against field strain Salmonella challenge were variable

and inconsistent.

Anti-BSA IgG levels were compared in broiler and SCWL chickens immunized

against BSA by a drinking water route of administration alone, or in combination with

two different concentrations of CpG-ODN or Non CpG-ODN in experiment 4. The

only observation where CpG-ODN and BSA co-administration resulted in anti-BSA

IgG levels that were elevated above BSA alone immunized chickens was measured in

broilers at day 19 post-final immunization.

Taken together, given the variable results reported in this investigation related

to the co-administration of ODN and vaccine or protein antigen, these data are largely

inconclusive for suggesting that CpG-ODN can effectively adjuvant humoral immune

responses in commercial strain chickens.