Dataset Information

Multilocus sequence typing of an emerging Cryptosporidium hominis subtype in the United States.

ABSTRACT: The United States has experienced a substantial increase in the reported incidence of cryptosporidiosis since 2005. Accompanying this is the emergence of a new subtype of Cryptosporidium hominis based on variation at the 60-kDa glycoprotein (gp60) locus, IaA28R4, which has become a frequently identified subtype in both sporadic and outbreak-related cases. In this study, using multilocus sequence typing (MLST) at eight genetic loci, we characterized 62 specimens of IaA28R4 and 33 specimens of three other gp60 subtypes of C. hominis from four U.S. states with increased cryptosporidiosis incidences during the summer of 2008. Extensive genetic heterogeneity was seen within the gp60 subtype IaA28R4, but specimens from Ohio and southwestern states formed two distinct subpopulations, suggesting that there were at least two origins of IaA28R4 within the United States. Discordance in typing results was observed between gp60 and other genetic markers, especially DZ-HRGP, and this discordance was largely the result of genetic recombination within the gp60 subtype IaA28R4. The results of population genetic analyses supported the presence of two subpopulations of IaA28R4 and the occurrence of genetic recombination within this gp60 subtype. Thus, the IaA28R4 subtype at gp60 is likely a fitness marker for C. hominis, and genetic recombination is potentially a driving force in the emergence of the virulent IaA28R4 subtype in the United States. A rapid evolution of IaA28R4 was indicated by the observation of multiple MLST subtypes of IaA28R4 within two large outbreaks that lasted for extended periods and involved multiple swimming pools.

SUBMITTER: Feng Y

PROVIDER: S-EPMC3911340 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Multilocus sequence typing of an emerging Cryptosporidium hominis subtype in the United States.

Feng Yaoyu Y Tiao Narry N Li Na N Hlavsa Michele M Xiao Lihua L

Journal of clinical microbiology 20131204 2

The United States has experienced a substantial increase in the reported incidence of cryptosporidiosis since 2005. Accompanying this is the emergence of a new subtype of Cryptosporidium hominis based on variation at the 60-kDa glycoprotein (gp60) locus, IaA28R4, which has become a frequently identified subtype in both sporadic and outbreak-related cases. In this study, using multilocus sequence typing (MLST) at eight genetic loci, we characterized 62 specimens of IaA28R4 and 33 specimens of thr ...[more]

PMID: 24478483

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Project description:UnlabelledThe use of a multilocus sequence typing (MLST) technique has identified the intraspecific genetic diversity of U.S. Flavobacterium psychrophilum, an important pathogen of salmonids worldwide. Prior to this analysis, little U.S. F. psychrophilum genetic information was known; this is of importance when considering targeted control strategies, including vaccine development. Herein, MLST was used to investigate the genetic diversity of 96 F. psychrophilum isolates recovered from rainbow trout (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Chinook salmon (Oncorhynchus tshawytscha) that originated from nine U.S. states. The isolates fell into 34 distinct sequence types (STs) that clustered in 5 clonal complexes (CCs) (n = 63) or were singletons (n = 33). The distribution of STs varied spatially, by host species, and in association with mortality events. Several STs (i.e., ST9, ST10, ST30, and ST78) were found in multiple states, whereas the remaining STs were localized to single states. With the exception of ST256, which was recovered from rainbow trout and Chinook salmon, all STs were found to infect a single host species. Isolates that were collected during bacterial cold water disease outbreaks most frequently belonged to CC-ST10 (e.g., ST10 and ST78). Collectively, the results of this study clearly demonstrate the genetic diversity of F. psychrophilum within the United States and identify STs of clinical significance. Although the majority of STs described herein were novel, some (e.g., ST9, ST10, ST13, ST30, and ST31) were previously recovered on other continents, which demonstrates the transcontinental distribution of F. psychrophilum genotypes.ImportanceFlavobacterium psychrophilum is the causative agent of bacterial cold water disease (BCWD) and rainbow trout fry syndrome (RTFS) and is an important bacterial pathogen of wild and farmed salmonids worldwide. These infections are responsible for large economic losses globally, yet the genetic diversity of this pathogen remains to be fully investigated. Previous studies have identified the genetic diversity of this pathogen in other main aquaculture regions; however, little effort has been focused on the United States. In this context, this study aims to examine the genetic diversity of F. psychrophilum from the United States, as this region remains important in salmonid aquaculture.

Dataset Information

Multilocus sequence typing of an emerging Cryptosporidium hominis subtype in the United States.

Publications

Multilocus sequence typing of an emerging Cryptosporidium hominis subtype in the United States.

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