Disparate thermostability profiles and HN gene domains of field isolates of Newcastle disease virus from live bird markets and waterfowl in Uganda
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Date
2016
Journal Title
Journal ISSN
Volume Title
Publisher
Virology Journal
Abstract
Uganda poultry production is still faced with frequent outbreaks of Newcastle disease (ND) in the
backyard free-range systems despite the accessibility of cross protective vaccines. Live bird markets and waterfowl
has long been reported as a major source of disease spread as well as potential sources of avirulent strains that
may mutate to virulent strains. ND-virus has been reported enzootic in Ugandan poultry but limited studies have
been conducted to ascertain thermostability phenotypes of the Ugandan ND-virus strains and to understand how
these relate to vaccine strains.
Methods: This study evaluated thermostability of 168 ND-virus field isolates recovered from live bird markets and
waterfowls in Uganda compared to two live commercial vaccine strains (I2 and LaSota) by standard thermostability
procedures and Hemagglutinin-Neuraminidase (HN) gene domains. The known pathotypes with thermostability
profiles were compared at HN amino acid sequences.
Results: Field isolates displayed disparate heat stability and HN gene domains. Thermolabile isolates were inactivated
within 15 min, while the most thermostable isolates were inactivated in 120 min. Four thermostable isolates had more
than 2 log2 heamaglutinin (HA) titers during heat treatment and the infectivity of 9.8 geometric mean of log10 EID50 % in
embryonated eggs. One isolate from this study exhibited a comparable thermostability and stable infectivity titers after
serial passages, to that of reference commercial vaccine was recommended for immunogenicity and protection studies.
Conclusion: The occurrence of ND-virus strains in waterfowl and live bird markets with disparate thermostability
and varying HN gene domains indicate circulation of different thermostable and thermolabile ND-virus pathotypes
in the country.
Description
Keywords
Thermostability, Infectivity, Thermostable isolate, Hemagglutionation assay
Citation
Omony, J. B., Wanyana, A., Mugimba, K. K., Kirunda, H., Nakavuma, J. L., Otim-Onapa, M., & Byarugaba, D. K. (2016). Disparate thermostability profiles and HN gene domains of field isolates of Newcastle disease virus from live bird markets and waterfowl in Uganda. Virology Journal, 13(1), 1-13. DOI 10.1186/s12985-016-0560-0