Complete Genome Sequences of Six Legionella pneumophila Isolates from Two Collocated Outbreaks of Legionnaires’ Disease in 2005 and 2008 in Sarpsborg/Fredrikstad, Norway

Here, we report the complete genome sequences of Legionella pneumophila isolates from two collocated outbreaks of Legionnaires’ disease in 2005 and 2008 in Sarpsborg/Fredrikstad, Norway. One clinical and two environmental isolates were sequenced from each outbreak. The genome of all six isolates consisted of a 3.36 Mb-chromosome, while the 2005 genomes featured an additional 68 kb-episome sharing high sequence similarity with the L. pneumophila Lens plasmid. All six genomes contained multiple mobile genetic elements including novel combinations of type-IVA secretion systems. A comparative genomics study will be launched to resolve the genetic relationship between the L. pneumophila isolates.

capable of airborne transmission from contaminated freshwater systems to susceptible humans, resulting in a severe pneumonia known as Legionnaires' disease (1). Sequence-based typing is the standard subtyping method for L. pneumophila (2), however, recent cost reductions and increased availability have enabled whole-genome sequencing-based subtyping (3).
Here, we report complete genome sequences of L. pneumophila isolates from two collocated outbreaks of Legionnaires' disease in 2005 and 2008 in Sarpsborg/Fredrikstad, Norway (Table 1). One clinical and two environmental isolates were sequenced from each outbreak. Additional isolate information has been reported elsewhere (4)(5)(6)(7).
All genomes consisted of a 3.36 Mb-chromosome, while the 2005 genomes featured an additional 68 kb-episome showing high similarity (Ͼ97%) with a 39 kb-region of the 60 kb-episome of L. pneumophila Lens (Table 1). Average coverage was 284ϫ (RSII) and 466ϫ (MiSeq). All genomes showed conserved syntheny with other L. pneumophila genomes and highest degree of similarity with Lens (Ͼ95%), in agreement with previous sequence-based typing (6). Average GϩC content was 38.5% and number of protein-coding genes  (3,9). All genomes contained Dot/Icm type-IVB secretion system (T4BSS) and genomic island-associated T4ASS (GI-T4ASS). None of the genomes contained Lvh T4ASS, which is present in Lens (3), while all genomes contained Trb (Ptype) T4ASS, which is absent in Lens. The 2008 genomes contained a Trb similar to the one in Corby/Alcoy, while the 2005 genomes contained a Trb similar to the one in Lorraine (3). Only the 2005 genomes contained Tra (F-type) T4ASS, which also is present in Lens. Tra was same as in Lens located on the episome in the 2005 genomes. All genomes contained additional virulence-associated elements including RtxA (10) and clustered regularly interspaced short palindromic repeats (CRISPR)-associated systems (Cas) (11). The RtxA in the 2005 genomes shared high similarity (Ͼ92%) with the one in Lens, while the RtxA in the 2008 genomes was more similar to the one in Corby/Alcoy. Comparative genomics will be used to resolve the genetic relationship between the sequenced isolates. Efforts to increase the availability of L. pneumophila genomes may serve as an important catalyst of advancements in this field.
Accession number(s). This whole-genome sequencing (WGS) project was deposited in GenBank under the accession numbers listed in Table 1.

ACKNOWLEDGMENTS
This work was funded by the Norwegian Defence Research Establishment FFI.
The sequencing service was provided by the Norwegian Sequencing Centre hosted by the University of Oslo and supported by the Research Council of Norway and the Southeastern Regional Health Authorities. We thank the Norwegian Institute of Public Health, the Health Authorities of the City of Fredrikstad, and Borregaard Industrier for providing us with the L. pneumophila isolates.

FUNDING INFORMATION
This work was funded by the Norwegian Defence Research Establishment FFI.