Cholera Toxin Production in Vibrio cholerae O1 El Tor Biotype Strains in Single-Phase Culture

Abstract

Vibrio cholerae O1 serogroup strains have been classified into classical and El Tor biotypes. Cholera, a life-threatening diarrheal disease, can be caused by either biotype through the cholera toxin (CT) that they produce. To increase our knowledge of the pathogenicity of bacteria, we must understand the toxigenicity of bacteria. CT production by classical biotype strains in simple single-phase cell cultures has been established; however, special culture media and growth conditions that are not appropriate for mass production of CT are required to facilitate CT production in El Tor biotype strains. In this report, we produced CT in El Tor biotype strains using simple media and single-phase culture conditions. A single point mutation in ToxT, a transcriptional activator of toxin co-regulated pilus (TCP) and CT, enabled the El Tor biotype strains to produce CT in similar quantities as classical biotype strains in singlephase laboratory culture conditions. CT production capacity varied between El Tor biotype strains. Wave 2 and 3 atypical El Tor strains tended to produce more CT than prototype Wave 1 strains. Wave 2 and 3 strains lack neutral fermentation; however, the capacity for neutral fermentation was not associated with significant differences in CT production by El Tor biotype strains. The Wave 3 strain that caused the 2010 cholera outbreak in Haiti produced CT only when neutral fermentation was abolished. The disparity in CT production between the seventh cholera pandemic strains highlight the differences in virulence between strains and the cause of population changes in V. cholerae.

In Vitro and In Vivo Inhibitory Activities of Selected Traditional Medicinal Plants against Toxin-Induced Cyto- and Entero- Toxicities in Cholera

“…This study utilised the cell free culture filtrate of O1 El Tor Ogawa V. cholerae isolated from clinical samples during the cholera out-breaks in Karnataka, India [ 15 , 16 ] for both in vitro as well as in vivo studies. It has been well reported that O1 El Tor Ogawa strain of V. cholerae produce Cholera toxin [ 17 ], non-membrane damaging cytotoxin [ 18 ] into culture supernatant along with other toxins such as Accessory Cholera toxin [ 19 ], Zonula occludens toxin [ 20 ], Multifunction auto processing repeats-in-toxin [ 21 ], Haemolysin [ 22 ] which are responsible for the pathogenesis of V. cholerae . Previous research has shown that the bacterium efficiently secretes both CT and NMDCY in AK1 media [ 23 , 24 ].…”

Inactivated Vibrio cholerae Strains That Express TcpA via the toxT-139F Allele Induce Antibody Responses against TcpA

“…TcpA expression in V. cholerae strains was examined in various culture media (LB, LB Tris-Cl pH 6.5, PBS-buffered LB, and AKI media) at 30°C or 37°C as described [ 37 ]. The optimal culture conditions for expression of TcpA for the bacterial strains were determined as follows; E. coli DH5α, V. cholerae O395, YJB001 (O395- toxT -139F), EJK003 (Cairo48- toxT -139F), JHB001 (Cairo48- toxT -139F- tcpA -ET), EJK005 (Phil6973- toxT -139F), EJK006 (4260B- toxT -139F), 569B, and EJK007 (569B- toxT -139F) have been cultured in LB media at 30°C.…”

“…pCVD442- toxT -139F was conjugally transferred to strains O395, N16961, T19479, EJK001 (IB5230-ch1-kan), Cairo48, Cairo50, Phil6973, 4260B, and 569B to replace their toxT -139Y allele with toxT -139F. The replacement of the toxT allele in each strain was confirmed by sequencing [ 36 , 37 ].…”

“…Recently, we have reported that the toxT -139F allele facilitates the production of CT in El Tor and classical biotype strains [ 36 - 38 ]. In the current study, V. cholerae strains—O395- toxT -139F, a derivative of the classical biotype strain O395, and IB5230- toxT -139F, a derivative of a Wave 3 El Tor biotype strain—that produce CT via the toxT -139F allele were examined for their ability to stably express TCP and induce antibody responses against TCP in an animal model.…”

Rapid and Visualized Detection of Virulence-Related Genes of Vibrio cholerae in Water and Aquatic Products by Loop-Mediated Isothermal Amplification

“…The World Health Organization estimated that cholera infects 1 to 4 million people and claims up to 143,000 lives each year (31). Cholera toxin and toxin-coregulated pilus are two major virulence factors produced by epidemic V. cholerae strains of serotypes O1 and O139 (2). Nevertheless, some non-O1/ O139 strains that do not produce cholera toxin and toxincoregulated pilus have been reported to cause sporadic diarrhea and gastroenteritis in humans, indicating that other virulence factors exist (33).…”