Abstract
BackgroundV. cholerae is the etiological agent of cholera, a major public health concern in most developing countries. Virulence of V. cholerae relies on the powerful cholera toxin, encoded by the CTX prophage. The emergence of new pathogenic variants in the recent years has been mostly associated with new CTX prophage rearrangements.ResultsIn this retrospective study, we show that the epidemic V. cholerae O1 El Tor strain responsible for the 2006 outbreak in Angola is clonally and genetically different from El Tor strains circulating in the 1990s in the same area. Strains from 2006 carry ICEVchAng3 of the SXT/R391 family. This ICE is associated with a narrower multidrug resistance profile compared to the one conferred by plasmid p3iANG to strains of the 1990s. The CTX prophage carried by 2006 El Tor strains is characterized by rstRET and ctxBCla alleles organized in a RS1-RS2-Core array on chromosome I. Interestingly, the newly emerging atypical strain belongs to a clade previously known to comprise only clinical isolates from the Indian subcontinent that also contain the same ICE of the SXT/R391 family.ConclusionsOur findings remark the appearance of a novel V. cholerae epidemic variant in Africa with a new CTXΦ arrangement previously described only in the Indian Subcontinent.
Highlights
V. cholerae is the etiological agent of cholera, a major public health concern in most developing countries
The use of horizontally-transferred elements as genetic markers for strain discrimination might appear risky, we recently showed the existence of an Integrative Conjugative Elements (ICEs)/strain association in epidemic V. cholerae strains circulating in the Indian Subcontinent [16]
V. cholerae strains from 2006 show reduced resistance profile compared to previous epidemic strains We analyzed two V. cholerae O1 El Tor clinical strains, VC175 and VC189 (Table 1), isolated at the Luanda Central Hospital (Angola)
Summary
V. cholerae is the etiological agent of cholera, a major public health concern in most developing countries. Virulence of V. cholerae relies on the powerful cholera toxin, encoded by the CTX prophage. Vibrio cholerae is the etiological agent of the severe watery diarrhoeal disease known as cholera, a major public health concern in most developing countries. Pathogenic V. cholerae strains carry the genes encoding the cholera toxin (CT) on the CTXF prophage. Different CTXF arrangements have been described within the O1 serogroup [2]. These arrangements depend on the genotype of the CT gene ctxB and on the organization and chromosomal location of several gene clusters of phage origin, namely the core, RS2, and RS1 [2]
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