Cross-Reactive Bactericidal Antimeningococcal Antibodies Can Be Isolated From Convalescing Invasive Meningococcal Disease Patients Using Reverse Vaccinology 2.0

Abstract

The threat from invasive meningococcal disease (IMD) remains a serious source of concern despite the licensure and availability of vaccines. A limitation of current serogroup B vaccines is the breadth of coverage afforded, resulting from the capacity for extensive variation of the meningococcus and its huge potential for the generation of further diversity. Thus, the continuous search for candidate antigens that will compose supplementary or replacement vaccines is mandated. Here, we describe successful efforts to utilize the reverse vaccinology 2.0 approach to identify novel functional meningococcal antigens. In this study, eight broadly cross-reactive sequence-specific antimeningococcal human monoclonal antibodies (hmAbs) were cloned from 4 ml of blood taken from a 7-month-old sufferer of IMD. Three of these hmAbs possessed human complement-dependent bactericidal activity against meningococcal serogroup B strains of disparate PorA and 4CMenB antigen sequence types, strongly suggesting that the target(s) of these bactericidal hmAbs are not PorA (the immunodominant meningococcal antigen), factor-H binding protein, or other components of current meningococcal vaccines. Reactivity of the bactericidal hmAbs was confirmed to a single ca. 35 kDa protein in western blots. Unequivocal identification of this antigen is currently ongoing. Collectively, our results provide proof-of-principle for the use of reverse vaccinology 2.0 as a powerful tool in the search for alternative meningococcal vaccine candidate antigens.

A novel pentavalent vaccine candidate completely protects against Acinetobacter baumannii in a mouse model of peritonitis

“…ELISA technique was used to determine the cross-reactivity of the immune serum developed against each immunogen (recombinant proteins, capsular polysaccharides, or the pentavalent pool) with A. baumannii clinical isolates. ELISA assays were carried out according to the previously described protocol (Kohl and Ascoli 2017 ; Bidmos et al, 2018 ) with minor modifications, where A. baumannii isolates were cultured at 37 °C with shaking at 2000 rpm in LB broth media overnight. The pellets were obtained by centrifugation at 4000 rpm for 10 min and washed 3 times with TBS.…”

Bacterial Vaccine Antigen Discovery in the Reverse Vaccinology 2.0 Era: Progress and Challenges

“…Taken together with other studies investigating the importance of antibody-mediated neutralization of intracellular pathogens ( 60 ), a role for the vaccine-induced generation of antibodies against pathogens such as MTB and Chlamydia trachomatis , using antigens derived with RV 2.0 is, thus, evidenced. Similarly, Bidmos et al ( 61 ) and Blum et al ( 45 ) cloned functional antibodies from sufferers of meningococcal and Lyme disease, respectively; thus, underscoring the utility of the approach for identifying novel targets in different classes of bacteria. Continued use of RV 2.0 in bacterial vaccine discovery is, therefore, encouraged following the surmounting of technical challenges and filling of research gaps.…”

Increasing human monoclonal antibody cloning efficiency with a whole-cell modified immunoglobulin-capture assay (mICA)

“…Cloning of the variable regions of IgG heavy and light chains (V H ; and VL = k/l) into relevant AbVec IgG expression vectors and subsequent expression of hmAbs was performed as previously described (22). A slight modification to the protocol involved substituting restriction endonuclease cloning with a ligationindependent method using the InFusion HD Cloning Plus system (Takara Bio) for enhanced cloning efficiency.…”

“…Protein epitope-specific hmAbs were assayed via western blotting, as previously described (22). Briefly, meningococci were lysed in 1x Laemmli buffer at 98 0 C, 5 minutes.…”