Biology subjects

Pierleoni, G.

Publications and source records attributed to Pierleoni, G..

5 recordsLinked to original sources

bioRxiv2025

Antigen-agnostic identification of poxvirus broadly neutralizing antibodies targeting OPG153

Recurrent mpox outbreaks caused by the monkeypox virus (MPXV) have prompted the World Health Organization to declare a Public Health Emergency of International Concern and have stimulated the development of medical interventions. Here, antigen-agnostic isolation of neutralizing monoclonal antibodies from convalescent or vaccinated people, AlphaFold 3-based predictive modeling, and cryo-electron microscopy were synergistically combined to identify the protein encoded by orthopoxviral gene (OPG) 153 (MPXV A28) as a target of broadly neutralizing antibodies. OPG153-targeting antibodies neutralized MPXV clade Ib, IIb, and vaccinia virus (VACV), and cross-reacted with OPG153 orthologs from cowpox and variola viruses. Immunization with MPXV OPG153 elicited a potent neutralizing antibody response against MPXV and VACV, substantiating OPG153 as a promising vaccine antigen and a potent target for preventive and therapeutic antibodies.

microbiology↗

bioRxiv2024

B cell maturation restored ancestral germlines to control Omicron BA.2.86

The unceasing interplay between SARS-CoV-2 and the human immune system has led to a continuous maturation of the virus and B cell response providing an opportunity to track their evolution in real time. We longitudinally analyzed the functional activity of almost 1,000 neutralizing human monoclonal antibodies (nAbs) isolated from vaccinated people, and from individuals with hybrid and super hybrid immunity (SH), developed after three mRNA vaccine doses and two breakthrough infections. The most potent neutralization and Fc functions against highly mutated variants, including BA.2.86, were found in the SH cohort. Despite different priming, epitope mapping revealed a convergent maturation of the functional antibody response. Neutralization was mainly driven by Class 1/2 nAbs while Fc functions were induced by Class 3/4 antibodies. Remarkably, broad neutralization was mediated by restored IGHV3-53/3-66 B cell germlines which, after heterogenous exposure to SARS-CoV-2 S proteins, increased their level of somatic hypermutations. Our study shows the resilience of the human immune system which restored previously expanded germlines and activated naive B cells to broaden the antibody repertoire of antibodies to control future SARS-CoV-2 variants.

immunology↗

bioRxiv2024

Discovery and Characterization of a Pan-betacoronavirus S2-binding antibody

SUMMARY/ABSTRACTThree coronaviruses have spilled over from animal reservoirs into the human population and caused deadly epidemics or pandemics. The continued emergence of coronaviruses highlights the need for pan-coronavirus interventions for effective pandemic preparedness. Here, using LIBRA-seq, we report a panel of 50 coronavirus antibodies isolated from human B cells. Of these antibodies, 54043-5 was shown to bind the S2 subunit of spike proteins from alpha-, beta-, and deltacoronaviruses. A cryo-EM structure of 54043-5 bound to the pre-fusion S2 subunit of the SARS-CoV-2 spike defined an epitope at the apex of S2 that is highly conserved among betacoronaviruses. Although non-neutralizing, 54043-5 induced Fc-dependent antiviral responses, including ADCC and ADCP. In murine SARS-CoV-2 challenge studies, protection against disease was observed after introduction of Leu234Ala, Leu235Ala, and Pro329Gly (LALA-PG) substitutions in the Fc region of 54043-5. Together, these data provide new insights into the protective mechanisms of non-neutralizing antibodies and define a broadly conserved epitope within the S2 subunit.

molecular biology↗

bioRxiv2022

mRNA vaccines and hybrid immunity use different B cell germlines to neutralize Omicron BA.4 and BA.5

SARS-CoV-2 omicron BA.4 and BA.5, characterized by high transmissibility and ability to escape natural and vaccine induced immunity, are rampaging worldwide. To understand the escape mechanisms, we tested the neutralizing activity against omicron BA.4 and BA.5 of a panel of 482 human monoclonal antibodies that had been isolated from people who received two or three mRNA vaccine doses or from people that had been vaccinated after infection. None of the antibodies isolated after two vaccine doses neutralized omicron BA.4 and BA.5, while these variants were neutralized by approximately 15% of antibodies obtained from people that received three doses or had been vaccinated after infection. Remarkably, the antibodies isolated after three vaccine doses targeted mainly the receptor binding domain (RBD) Class 1/2 epitope region and were encoded by the IGHV1-69 and IGHV3-66 B cell germlines, while the antibodies isolated after infection recognized mostly the RBD Class 3 epitope region and the NTD, and were encoded by the IGHV2-5;IGHJ4-1 and IGHV1-24;IGHJ4-1 germlines. The observation that mRNA vaccination and hybrid immunity elicit a different immunity against the same antigen is intriguing and its understanding may help to design the next generation of therapeutics and vaccines against COVID-19.

immunology↗

bioRxiv2022

COVID-19 mRNA third dose induces a unique hybrid immunity-like antibody response

The continuous evolution of SARS-CoV-2 generated highly mutated variants, like omicron BA.1 and BA.2, able to escape natural and vaccine-induced primary immunity1,2. The administration of a third dose of mRNA vaccines induces a secondary response with increased protection. We investigated, at single-cell level, the longitudinal evolution of the neutralizing antibody response in four donors after three mRNA doses3. A total of 4,100 spike protein specific memory B cells were single cell sorted and 350 neutralizing antibodies were identified. The third dose increased the antibody neutralization potency and breadth against all SARS-CoV-2 variants of concern as previously observed with hybrid immunity3. However, the B cell repertoire that stands behind the response is dramatically different. The increased neutralizing response was largely due to the expansion of B cell germlines poorly represented after two doses, and the reduction of germlines predominant after primary immunization such as IGHV3-53;IGHJ6-1 and IGHV3-66;IGHJ4-1. Divergently to hybrid immunity, cross-protection after a third dose was mainly guided by Class 1/2 antibodies encoded by IGHV1-58;IGHJ3-1 and IGHV1-69;IGHJ4-1 germlines. The IGHV2-5;IGHJ3-1 germline, which induced broadly cross-reactive Class 3 antibodies after infection or viral vector vaccination, was not induced by a third mRNA dose. Our data show that while neutralizing breadth and potency can be improved by different immunization regimens, each of them has a unique molecular signature which should be considered while designing novel vaccines and immunization strategies.

immunology↗