Effect of immunosuppression on Newcastle disease virus persistence in ducks with different immune status

Njagi LW, Nyaga PN, Bebora LC. "Effect of immunosuppression on Newcastle disease virus persistence in ducks with different immune status." ISRN Veterinary Science. 2012.


International Scholarly Research Network
ISRN Veterinary Science
Volume 2012, Article ID 253809, 6 pages
Research Article
Effect of Immunosuppression on Newcastle Disease Virus Persistence in Ducks with Different Immune Status
LucyW. Njagi,1 Phillip N. Nyaga,1 Lilly C. Bebora,1 Paul G. Mbuthia,1 and UswegeM.Minga2
1Department of Veterinary Pathology, Microbiology and Parasitology, University of Nairobi, P.O. Box 29053-00625, Kangemi, Kenya
2Department of Life Sciences, FSTES, African Council for Distance Education—Technical Committee on Collaboration (ACDE-TCC),
Open University of Tanzania, P.O. Box 23409, Dar es Salaam, Tanzania
Correspondence should be addressed to LucyW. Njagi, njagiluc@uonbi.ac.ke
Received 30 November 2011; Accepted 4 January 2012
Academic Editors: A. Mankertz and I. Nsahlai
Copyright © 2012 LucyW. Njagi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This study was carried out to verify the possibility that ducks are sources of Newcastle disease (ND) virus infection for chickens in mixed flocks. Immunosuppressed (IS) and non immunosuppressed (NIS) birds, at three different antibody levels (medium, low and absent) were used; the titres having been induced through vaccination, and Immunosuppression done using dexamethazone. Each of the 3 respective groups was further divided into 2 groups of about 12 ducks each: one challenged with velogenic NDvirus; the other not challenged. Selected ducks fromall groups had their antibody titresmonitored serially using hemagglutination inhibition test, while two birds from each of the challenged groups were killed and respective tissues processed for ND viral recovery, using chicken embryo fibroblasts. In general, antibody titres of IS and NIS challenged ducks were significantly higher
than their unchallenged counterparts (P < 0.05). Non-challenged pre-immunised ducks had a progressive decrease in antibody levels; non-immunised ducks did not seroconvert. Newcastle disease virus was isolated from livers and kidneys of the challenged ducks throughout the experimental period; indicating a possibility of viral excretion, especially when the birds are stressed. It, therefore, provides another possible model of viral circulation within mixed flocks.

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