Objective To validate the biological function of Hk2,which is reported to be in combination with the cognate response regulator Rrp2 to constitute a two component signal system in Borrelia burgdorferi that controls the key virulence factors required for pathogen invasion in mammals. Methods A hk2 knockout strain (hk2^-) was generated through homologous recombination, with the biological function of Hk2 estimated by the mouse-tick animal model. Results The hk2^- knockout strain remained to be able to infect mouse by needle inoculation, and subsequently successfully detected in the midgut of fed-larvae and -nymph by IFA. The quantitative-PCR demonstrated that hk2 knockout had no influence on bacterial replication in the midgut of fed nymph. However, only 50% of tested mice were infected in hk2^- group by tick bite. Conclusion The hk2 knockout does not affect the pathogen acquisition from mouse by larvae ticks and subsequent persistent colonization in tick midgut, but it embarrasses the transmission from nymph to mouse under natural conditions by tick bite. The above data indicate that the Hk2 may effectively contribute to the pathogen invading mammals in the life cycle of B. burgdorferi.

【Abstract】 Objective To master the species and seasonal fluctuation of mosquitoes, and provide scientific basis for mosquitoes control in Beijing ports. Methods CO2?baited trap and net trap methods were used for the surveillance of adult mosquitoes, and the scoop dipping method for the surveillance of larvae. Results A total of 14 270 mosquitoes were collected, belonging to 4 genera and 6 species. They were  Anopheles sinensis, Culex pipiens pallens,  Cx.tritaeniorhynchus,  Aedes albopictus, Ae.vexans  and  Armigeres  subalbatus.  As  many  as  114  mosquito  larvae  were  collected,  which  were  Cx.pipiens  pallens  and Cx.modestus. The dominant specie was Cx.pipiens pallens and its active peak was September. Conclusion The integrated management should be taken for a long time to control mosquitoes in Beijing ports.

【Abstract】 Objective To master the fly species and population composition at Beijing port and provide scientific evidence for fly control. Methods The baited fly traps method was used in this study. Results There were 30 species, 16 genera, 5 families of flies captured from April to November of 2006 and 2007. The annual average fly density was 59.7 flies/(cage ·day). There were two peaks, one was in May and the other was in September. Conclusion It was important to clean out the breeding sites for the control of flies at Beijing port.