A value less than 0.05 was considered significant. Funding Statement This work was supported in part by National Institutes of Health grant R01-AI31940. all immunization groups that received CTB, quantitative ELISA data demonstrated that the amounts of serum IgG directed against the homologous immunizing CTB antigen was statistically greater than the amount to the heterologous CTB antigen (01 and 0139. Introduction The bacterium is the etiologic agent responsible for the acute diarrheal disease cholera. There are over 200 serogroups of cholera but only 2 are known to cause epidemics: 01 and 0139. Serogroup 01 can be further subdivided into the El Tor and classical biotypes each with several serotypes. Cholera is spread by the fecal-oral route and outbreaks are caused by contamination of food and water sources due to unsanitary conditions. Prevention of cholera outbreaks can be achieved with modern sanitation and safe potable water sources [1]. However for financially strapped, impoverished countries the overhaul of their hygienic infrastructure is difficult. The WHO estimates there are at least 884 million people who lack access to safe drinking water and another 2.6 billion without proper sanitation [2]. In lieu of adequate sanitation and safe water sources, the development of efficacious vaccines to prevent cholera is an appropriate goal for endemic and at risk countries. Unfortunately the currently licensed whole-cell killed vaccines (WCK) elicit limited long-term protection necessitating the development of more effective vaccines [3]. Once ingested colonizes the small intestine where it secretes cholera toxin (CT) [4]. Cholera toxin is the primary virulence factor responsible for CHIR-99021 monohydrochloride the profuse watery diarrhea associated with cholera. Cholera toxin is an AB5 toxin composed of one catalytic A polypeptide (CTA) and five identical B polypeptides (CTB) [5]. CTB is the nontoxic binding domain of CT, and it forms a donut-like structure composed of the five B polypeptides associated by non-covalent interactions. The nontoxic A2 domain of CTA passes through the central pore of CTB, tethering the A and B subunits together by non-covalent interactions [5]. CT secreted by binds to its receptor the monosialosyl ganglioside CHIR-99021 monohydrochloride GM1 on the host cells [6]. The bound toxin is internalized by endocytosis and retrograde transport, and the catalytic A fragment (CTA1) is delivered to the cytosol by retrotranslocation from the endoplasmic reticulum [7]. CTA1 ADP ribosylates the subunit of heterotrimeric stimulatory G protein (Gs) causing activation of adenylate cyclase and a rise in intracellular adenosine-3,5-monophosphate (cAMP) levels. The rise in cAMP levels triggers the opening of the chloride channels resulting in an efflux of ions and water into the intestines where it is eliminated in the stool and vomitus [7]. TcpF is a secreted virulence factor of unknown function that is thought to play a role in microcolony formation in the small intestine [8]. The gene is part of the operon which encodes another important virulence factor the toxin-coregulated pilus (TCP) [9]. TCP is a type IV pilus composed of the pilin subunit TcpA [10], and is absolutely required for colonization in mice and humans [11], [12]. expression of TCP causes the filaments to bundle to mediate bacterial autoagglutination [13]. CHIR-99021 monohydrochloride In the infant mouse, TCP functions by mediating bacterium-to-bacterium interactions as well as mediating attachment to epithelial cells [14]. Though it has been demonstrated that TCP is necessary for TcpF secretion [15], TcpF is not required for TCP autoagglutination and may play an independent role in colonization [8]. As with TCP, TcpF has also been shown to be necessary for colonization CHIR-99021 monohydrochloride in the infant mouse [8], [15]. Because of its importance in colonization TcpF Rabbit Polyclonal to ALK has been examined as a potential protective antigen in the development of a vaccine against 01. Studies using passively administered hyper-immune anti-TcpF sera demonstrated CHIR-99021 monohydrochloride protection in the infant mouse following oral challenge with lethal doses of 01 [8], [16]. It was also demonstrated that an anti-TcpF monoclonal antibody combined with a sub-protective dose of TcpA antisera provided additive protection compared to either antibody used alone [16]. The importance of.