%0 Journal Article
%T The type IV pilin, PilA, is required for full virulence of Francisella tularensis subspecies tularensis
%A Anna-Lena Forslund
%A Emelie Salomonsson
%A Igor Golovliov
%A Kerstin Kuoppa
%A Stephen Michell
%A Richard Titball
%A Petra Oyston
%A Laila Noppa
%A Anders Sj£¿stedt
%A £¿ke Forsberg
%J BMC Microbiology
%D 2010
%I BioMed Central
%R 10.1186/1471-2180-10-227
%X In a previous study, we were able to show that one pilin gene, pilA, was essential for virulence of a type B strain in a mouse infection model. In this work we have examined the role of several Tfp genes in the virulence of the pathogenic type A strain SCHU S4. pilA, pilC, pilQ, and pilT were mutated by in-frame deletion mutagenesis. Interestingly, when mice were infected with a mixture of each mutant strain and the wild-type strain, the pilA, pilC and pilQ mutants were out-competed, while the pilT mutant was equally competitive as the wild-type.This suggests that expression and surface localisation of PilA contribute to virulence in the highly virulent type A strain, while PilT was dispensable for virulence in the mouse infection model.Francisella tularensis is a Gram-negative facultative intracellular bacterial pathogen and the causative agent of tularemia. Infections have been reported in a range of vertebrates as well as invertebrates [1]. Natural infections can occur via ingestion of contaminated food or water, handling of infected animals, bites by infected arthropods, including mosquitoes and ticks, or via inhalation [2]. F. tularensis is divided into four subspecies, where ssp. holarctica (type B) is most widely spread and found in the major part of Europe, Asia, and North America. F. tularensis ssp. tularensis (type A) is found exclusively in North America and ssp. mediasiatica in Central Asia. Finally, ssp. novicida has been isolated in several locations in North America, as well as in Australia [3,4]. Human infections are mainly caused by type A or type B strains, where type A strains are significantly more virulent than type B strains. Our knowledge regarding virulence determinants in F. tularensis is rather limited. However, available genome information [5,6] together with development of genetic tools [7], has resulted in increased understanding of the molecular mechanisms of F. tularensis infections.The genome of F. tularensis encodes gene clusters inv
%U http://www.biomedcentral.com/1471-2180/10/227