title: Disparate thermostability profiles and HN gene domains of field isolates of Newcastle disease virus from live bird markets and waterfowl in Uganda.
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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: College of Veterinary Medicine, Makerere University, P.O. Box 7062, Kampala, Uganda.|Uganda Industrial Research Institute (UIRI), P.O. Box 7086, Kampala, Uganda.
authors.forename: John Bosco
authors.identifier: 0000-0003-1407-7204
authors.initials: JB
authors.lastname: Omony
authors.affiliation: College of Veterinary Medicine, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors.forename: Agnes
authors.initials: A
authors.lastname: Wanyana
authors.affiliation: College of Veterinary Medicine, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors.forename: Kizito K
authors.initials: KK
authors.lastname: Mugimba
authors.affiliation: Mbarara Zonal Agricultural Research and Development Institute (MBAZARDI), National Agricultural Research Organisation (NARO), P.O. Box 389,, Mbarara, Uganda.
authors.forename: Halid
authors.initials: H
authors.lastname: Kirunda
authors.affiliation: College of Veterinary Medicine, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors.forename: Jessica Lukanga
authors.initials: JL
authors.lastname: Nakavuma
authors.affiliation: Uganda National Council of Science & Technology (UNCST), P.O. Box 6884, Kampala, Uganda.
authors.forename: Maxwell
authors.initials: M
authors.lastname: Otim-Onapa
authors.affiliation: College of Veterinary Medicine, Makerere University, P.O. Box 7062, Kampala, Uganda. dkb@covab.mak.ac.ug.
authors.forename: Denis Karuhize
authors.initials: DK
authors.lastname: Byarugaba
mesh_terms: D000818:Animals; D046090:Anseriformes / Q000821:virology; D001715:Bird Diseases / Q000821:virology*; D001717:Birds / Q000821:virology; D015707:HN Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D009521:Newcastle Disease / Q000821:virology*; D009522:Newcastle disease virus / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D000072417:Protein Domains; D055550:Protein Stability; D014454:Uganda; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D015707:HN Protein; D014764:Viral Proteins
keywords: HN gene; Hemagglutionation assay; Infectivity; Thermostability; Thermostable isolate