Emergence of a novel multi-resistance-mediating integrative and conjugative element ICEPmu3 in Pasteurella multocida

Pasteurella multocida(PM)has been infecting a variety of hosts for a long time,causing sustained economic losses worldwide;however,there have been limited studies on its extensive adaptability(Aktories et al.2012).Analysis of strains data collected in our laboratory revealed that PM typically acquires foreign genes through transformation and conjugation,rather than transformation and fusion.Integrative and conjugative elements(ICEs)are a crucial mechanism that leads to abrupt changes in niche preferences and enhances environmental adaptability for bacteria,with their number far exceeding the number of plasmids and phages(Wozniak and Waldor 2010;Johnson and Grossman 2015;Botelho and Schulenburg 2021).Previous research has shown that the European bovine-sourced strain Pm36950 contains the experimentally transferable resistant ICEPmu1,which could integrate into the host chromosome or forming a circular intermediate(Michael et al.2012).Additionally,a few studies have suggested that PM strains isolated from European bovine and Asian swine might contain ICEs,but these claims lack experimental verification(Klima et al.2014;Moustafa et al.2015;Kadlec et al.2017;Peng et al.2017;Beker et al.2018;Schink et al.2022).Currently,there is no data available on ICE-carrying PM strains isolated from hosts outside of European cattle or Chinses swine.This letter presents a report on a novel ICE identified in the hypervirulent and multidrug-resistant PM HN141014 strain isolated from Chinese duck.The ICE was specifically analyzed for its resistance genes,transferable capacity and host diversity.

Comparative study of the pathogenicity of the mosquito origin strain and duck origin strain of Tembusu virus in ducklings and three-week-old mice

Dear Editor,Duck Tembusu virus(DTMUV)is the causative agent of a new,acute and severe infectious disease in ducks(Su et al.,2011).TMUV was first isolated from Culex tritaeniorhynchus in Malaysia in 1955(Platt et al.,1975),and this strain is regarded as a reference strain.In our previous study,an infectious clone for the mosquito-derived Tembusu virus prototypical strain MM_1775(GenBank:JX477685.2)was constructed,and the rMM_1775 virus was rescued successfully(Wang et al.,2021).And the TMUV strain rCQW1 was rescued by a reverse genetic system using the viral RNAs of CQW1(GenBank:KM233707.1)(Chen et al.,2018;Guo et al.,2020),which was isolated from ducks in 2013(Zhu et al.,2015).