A monoclonal antibody that targets the conserved core/lipid A region of lipopolysaccharide affects motility and reduces intestinal colonization of both classical and El Tor Vibrio cholerae biotypes

Abstract

Vibrio cholerae is the causative agent of cholera, an acute diarrheal disease that remains endemic in many parts of the world. The mechanisms underlying immunity to cholera remain poorly defined, though it is increasingly clear that protection is associated with antibodies against lipopolysaccharide (LPS). Here we report that ZAC-3, a monoclonal antibody against the core/lipid A region of V. cholerae LPS is a potent inhibitor of V. cholerae flagellum-based motility in viscous and liquid environments. ZAC-3 arrested motility of the classical Ogawa strain O395, as well as the El Tor Inaba strain C6706. In addition, we demonstrate, in the neonatal mouse model, that ZAC-3 IgG and Fab fragments significantly reduced the ability of both V. cholerae strains O395 and C6706 to colonize the intestinal epithelium, revealing the potential of antibodies against the core/lipid A to contribute to immunity across biotypes, possibly through a mechanism involving motility arrest.

Cholera: Immunity and Prospects in Vaccine Development

“…While antibody-dependent complement-mediated bacterial killing is an important defense against systemic infections, it is not thought to be important at the intestinal surface owing to low levels of complement at this site [ 25 ]. Instead, the inhibition of motility and trapping of bacterial pathogens in the mucus layer by dimeric IgA are considered likely effector functions of antibodies to prevent colonization by V. cholerae [ 26 , 27 ].…”

Vibrio cholerae O1 secretes an extracellular matrix in response to antibody-mediated agglutination

“…cholerae O1 LPS [ 21 , 24 , 29 , 30 ]. In a recent report, we demonstrated that ZAC-3 IgG agglutinated and arrested motility of the classical Ogawa type strain O395, as well as the El Tor Inaba strain C6706 [ 24 , 25 , 30 ]. To further assess ZAC-3 reactivity and its effects on bacterial motility, we probed a panel of V .…”

“…ZAC-3 is not reportedly bacteriostatic or bactericidal [ 24 , 30 ]. Nonetheless, we wished to rule out the possibility that the observed increase in CV staining upon ZAC-3 IgG treatment was simply due to adsorption of dead cells to the microtiter plate surface.…”

“…For example, ZAC-3 IgG causes a near complete arrest of V . cholerae motility within a matter of minutes in liquid medium and dramatically limits bacterial swimming through low percentage agarose [ 24 ]. In a recent report, Wang and colleagues attributed motility arrest by OSP-specific polyclonal antibodies elicited by vaccination with an outer membrane vesicle preparation as being the main driver of the immunity in a suckling mouse model [ 26 ].…”

“…The resulting chimeric mAb was expressed in a Nicotiana benthamiana -based rapid antibody-manufacturing platform (RAMP) [ 30 ]. We demonstrated that ZAC-3 IgG prevents classical (strain O395) and El Tor (C6706) biotypes from colonizing the intestinal epithelium in the neonatal mouse model [ 24 ]. ZAC-3 IgG was shown to be a potent inhibitor of V .…”