Infection with Brucella spp., long known as a cause of abortion, infertility, and reproductive loss in domestic livestock, has increasingly been documented in marine mammals over the past two decades. We report molecular evidence of Brucella infection in Asian sea otters (Enhydra lutris lutris). Brucella DNA was detected in 3 of 78 (4%) rectal swab samples collected between 2004 and 2006 on Bering Island, Russia. These 78 animals had previously been documented to have a Brucella seroprevalence of 28%, markedly higher than the prevalence documented in sea otters (Enhydra lutris) in North America. All of the DNA sequences amplified were identical to one or more previously isolated Brucella spp. including strains from both terrestrial and marine hosts. Phylogenetic analysis of this sequence suggested that one animal was shedding Brucella spp. DNA with a sequence matching a Brucella abortus strain, whereas two animals yielded a sequence matching a group of strains including isolates classified as Brucella pinnipedialis and Brucella melitensis. Our results highlight the diversity of Brucella spp. within a single sea otter population.
Comparative molecular-genetic typing of Brucella strains isolated in Mongolia from different animal species as well as from humans.
Twenty-one strains of Brucella isolated from different hosts in 7 provinces of Mongolia were typed. Conventional phenotypic methods, genotyping by PCR with primers for genus- and species-specific differentiating targets of Brucella genes as well as multiple locus variable number tandem repeats analysis (MLVA) with 12 pairs of primers bounding locus variable tandem repeats of different length (from 134 bp to 8 bp).
Phenotypic identification and genotyping by PCR using primers for differentiating DNA markers allowed to attribute 14 isolates to B. melitensis biovar 2, and 7 - to B. abortus biovar 3. By using the MLVA method, connection of MLVA genotypes of 9 Brucella isolates with their reservoir hosts (sheep, cows) was shown providing their circulation in Khentii, Bulqan, and Khubsgul provinces bordering with Russia. Nine isolates from different hosts (camel, yaks, goats, sheep) isolated in Ovorkhangai, Dundgovi, and Dornogovi provinces, which have not border with Russia, had closely related MLVA genotypes indicating an opportunity of migration of pathogenic Brucella species to not-typical hosts.
Molecular-genetic typing of Brucella isolated in Mongolia was done for the first time; levels of their genetic relation and diversity were demonstrated. Circulation of Brucella isolated with specific MLVA genotypes was connected to territories of specific Mongolian provinces. The study proved migration of Brucella to not-typical hosts. Comparative study of isolates circulating in frontier with Mongolia areas of Russia (Irkutsk region, Tyva and Buryat Republics) are necessary to perform.