ARS | Publication request: Variable Nucleotide Tandem-Repeat Analysis Revealing a Unique Group of Leptospira interrogans Serovar Pomona Isolates Associated with California Sea Lions

Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 2009
Publication Date: April 1, 2009
Citation: Zuerner, R.L., Alt, D.P. 2009. Variable Nucleotide Tandem-Repeat Analysis Revealing a Unique Group of Leptospira interrogans Serovar Pomona Isolates Associated with California Sea Lions. Journal of Clinical Microbiology. 47(4):1202-1205.

Interpretive Summary: Leptospirosis is one of the most widespread bacterial zoonoses known. Pathogenic Leptospira can infect most mammals, but the outcome of infection varies depending on host species and infecting strain. Typically, leptospirosis can either develop into a chronic infection in a maintenance host or an acute, potentially lethal infection in an accidental host. Infections with serovar Pomona appear to be different, in that acute and chronic infections can occur in the same host species. We used a molecular typing method that looks at changes in the sizes of DNA fragments at specific regions of the genome to characterize serovar Pomona strains. We found several distinct groups of serovar Pomona isolates. These data should help us answer questions about the interactions between leptosprial strains and specific mammalian hosts.

Technical Abstract: Leptospira interrogans serovar Pomona is commonly isolated from a variety of wildlife and domesticated livestock. It is difficult to assess whether disease outbreaks with serovar Pomona in given animal populations are due to endemic infections or accidental exposure. Unlike many leptospiral serovars, serovar Pomona infections do not appear to fit the maintenance host-accidental host paradigm. We compared a collection of fifty-seven L. interrogans serovar Pomona isolates by variable nucleotide tandem repeat (VNTR) typing. These isolates were collected from diverse geographical loci and from various wildlife and domesticated species. Most isolates from cattle were grouped together, while porcine isolates were distributed across several different VNTR clusters. All isolates from California sea lions formed a distinct group; these data are consistent with recent findings that leptospirosis is endemic in California sea lion populations. These data suggest sea lions function as maintenance hosts for serovar Pomona and that this disease is perpetuated by sea lion to sea lion transmission.