Traditionally, vaccines have been developed empirically by isolating, inactivating, and injecting the microorganisms (or portions of them) that cause disease (Table 1; Rappuoli, 2014). Two decades ago, genome sequencing revolutionized this process, allowing for the discovery of novel vaccine antigens starting directly from genomic information. The process was named "reverse vaccinology" to underline that vaccine design was possible starting from sequence information without the need to grow pathogens (Rappuoli, 2000). Indeed, a vaccine against meningococcus B, the first deriving from reverse vaccinology, has recently been licensed (Serruto et al., 2012;O'Ryan et al., 2014). Today, a new wave of technologies in the fields of human immunology and structural biology provide the molecular information that allows for the discovery and design of vaccines against respiratory syncytial virus (RSV) and human CMV (HCMV) that have been impossible thus far and to propose universal vaccines to tackle influenza and HIV infections. Here, we provide our perspective (summarized in Table 1) of how several new advances, some of which have been partially discussed elsewhere (Burton, 2002;Dormitzer et al., 2012;Haynes et al., 2012), can be synergized to become the engine driving what might be considered a new era in vaccinology, an era in which we perform "reverse vaccinology 2.0." Several technological breakthroughs over the past decade have potentiated vaccine design. First, the greatly enhanced ability to clone human B cells and then to produce the corresponding recombinant mAbs or antigen-binding fragments (Fab's) has provided access to an enormously rich set of reagents that allows for the proper evaluation of the protective human immune response to any given immunogen upon immunization or infection. A fundamental step for the success of this approach has been the growing capacity to select the most favorable donors for the isolation of the most potent antibodies (Abs) through extensive examination of serum-functional Ab responses. Second, conformational epitope mapping studies, performed via improved structural biology tools for the three-dimensional characterization of Fab's complexed with their target antigens , can now readily yield the atomic details of protective epitopes recognized by broadly neutralizing Abs (NAbs [bNAbs]). Third, new computational approaches, informed by such structural and immunological data, have enabled the rational design of novel immunogens to specifically elicit a focused immune response targeting the most desirable protective epitopes (Liljeroos et al., 2015). In addition to these advances, a great improvement in RNA sequencing technology has allowed for a massive analysis of the B cell repertoire, providing an accurate overview of the Ab maturation process generated by an infection or vaccination and driving new strategies aimed at priming the B cell precursors expressing germline-encoded Abs in an effective way before initiation of any somatic mutation. Human B cell technologies to identify fu...

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Chlamydia pneumoniae, a human pathogen causing respiratory infections and probably contributing to the development of atherosclerosis and heart disease, is an obligate intracellular parasite which for replication needs to productively interact with and enter human cells. Because of the intrinsic difficulty in working with C. pneumoniae and in the absence of reliable tools for its genetic manipulation, the molecular definition of the chlamydial cell surface is still limited, thus leaving the mechanisms of chlamydial entry largely unknown. In an effort to define the surface protein organization of C. pneumoniae, we have adopted a combined genomicproteomic approach based on (i) in silico prediction from the available genome sequences of peripherally located proteins, (ii) heterologous expression and purification of selected proteins, (iii) production of mouse immune sera against the recombinant proteins to be used in Western blotting and fluorescence-activated cell sorter (FACS) analyses for the identification of surface antigens, and (iv) mass spectrometry analysis of two-dimensional electrophoresis (2DE) maps of chlamydial protein extracts to confirm the presence of the FACS-positive antigens in the chlamydial cell. Of the 53 FACS-positive sera, 41 recognized a protein species with the expected size on Western blots, and 28 of the 53 antigens shown to be surface-exposed by FACS were identified on 2DE maps of elementary-body extracts. This work represents the first systematic attempt to define surface protein organization in C. pneumoniae.Chlamydia pneumoniae is an obligate intracellular bacterium and a common human pathogen (48). It is a significant cause of pneumonia in both hospital and outpatient settings, accounting for approximately 7 to 10% of cases of community-acquired pneumonia among adults. C. pneumoniae has also been associated with atherosclerotic and cardiovascular disease, as suggested by results of seroepidemiologic studies, detection of the organism in atherosclerotic plaque specimens, experimental in vitro cell culture studies, animal model studies, and two small secondary prevention antibiotic treatment trials (12,13,15,19,20,28,45).Like all obligate intracellular parasites, for its survival and propagation C. pneumoniae must accomplish several essential tasks which include adhering to and entering host cells, creating an intracellular niche for replication, exiting host cells for subsequent invasion of neighboring cells, and also avoiding host defense mechanisms. To carry out all these functions, C. pneumoniae has developed a unique biphasic life cycle involving two developmental forms, a spore-like infectious form (elementary bodies [EBs]) and an intracelluar replicative form (reticulate bodies [RBs]). Adhesion, host cell colonization capabilities, and the ability to cope with host defense mechanisms when outside the cell presumably rely in large part on EB surface organization.Because of the intrinsic difficulty in working with C. pneumoniae and the lack of adequate methods for its genetic ma...

4CMenB is the first broad coverage vaccine for the prevention of invasive meningococcal disease caused by serogroup B strains. To gain a comprehensive picture of the antibody response induced upon 4CMenB vaccination and to obtain relevant translational information directly from human studies, we have isolated a panel of human monoclonal antibodies from adult vaccinees. Based on the Ig-gene sequence of the variable region, 37 antigen-specific monoclonal antibodies were identified and produced as recombinant Fab fragments, and a subset also produced as full length recombinant IgG1 and functionally characterized. We found that the monoclonal antibodies were cross-reactive against different antigen variants and recognized multiple epitopes on each of the antigens. Interestingly, synergy between antibodies targeting different epitopes enhanced the potency of the bactericidal response. This work represents the first extensive characterization of monoclonal antibodies generated in humans upon 4CMenB immunization and contributes to further unraveling the immunological and functional properties of the vaccine antigens. Moreover, understanding the mechanistic nature of protection induced by vaccination paves the way to more rational vaccine design and implementation.