Biology subjects

Gottlieb, P.

Publications and source records attributed to Gottlieb, P..

2 recordsLinked to original sources

bioRxiv2025

The structure of the Human Adenovirus 7 virus-like particles reveals that pentons and core-genome promote hexon-pIIIa interactions during capsid maturation

Members of the Adenoviridae family routinely infect humans, exhibit significant genetic diversity, and are associated with a variety of illnesses. Types 4 and 7 frequently circulate in the United States and are major causes of respiratory disease. Infections can result in hospitalization and, in severe cases, death. Although a live wild-type-virus vaccine targeting these two types exists, its use is restricted to military personnel due to concerns about viral-shedding and the potential for genetic recombination. To overcome these limitations, we recently developed a virus-like particle (VLP) platform as an alternative vaccination strategy. These VLPs are stable, lack genomic material, and elicit a potent humoral immune response in mice, effectively neutralizing adenoviral infection. Here, we describe the cryo-EM structure of these VLPs at near atomic resolution. Structural insights are essential to ensure that the neutralizing antigens displayed on the VLPs accurately mimic those of the infectious virion, guide the design of particles with improved stability and efficacy, and enable engineering of VLPs with antigenic properties targeting multiple adenovirus types. The structure confirms that the key epitopes capable of eliciting neutralizing antibodies are appropriately displayed for antibody recognition. It also reveals previously unobserved interactions critical for capsid maturation. The penton base adopts multiple conformations when interacting with hexons, and its proper positioning is necessary to facilitate hexon-pIIIa interactions that stabilize the capsid. A comparison of the VLP with immature and mature adenovirus structures shows that core-genome packaging strengthens interaction between cementing proteins pIIIa and pVIII and the hexon shell. Significance StatementAdenoviruses are large and morphologically complex family of viruses that undergo a sophisticated process of assembly and maturation. These viruses are responsible for ocular, respiratory, and enteric infections, posing a particular risk to children and the immunocompromised. Despite their clinical significance, there are no adenovirus vaccines available to the public. Here we report the cryo-electron microscopy structure of human adenovirus 7 virus-like particles, which have shown strong potential as a vaccine candidate. Our analysis provides critical insights for the design of particles as vaccines or carriers of genetic therapeutics. The structure reveals how interaction between hexon and penton promote cement protein pIIIa for increased capsid interaction, and how core-genome packaging contributes to capsid maturation and enhanced capsid stability.

biophysics↗

bioRxiv2019

Structural characterization of the PCV2d genotype at 3.3 A resolution reveals differences to PCV2a and PCV2b genotypes, a tetranucleotide, and an N-terminus near the icosahedral 3-fold axes

Porcine circovirus 2 (PCV2) is a T=1 non-enveloped icosahedral virus that has a major impact on the swine industry as an agent of porcine circovirus associate disease. PCV2 capsid protein sequences have been employed by others to provide a temporal description of the emerging genotypes. PCV2a is believed to be the earliest genotype and responsible for giving rise to PCV2b, which gives rise to PCV2d. The underlying mechanism responsible for the emerging genotypes is not understood. To determine if a change in the PCV2d capsid accompanies the emergence of this genotype, we determined the cryo-electron microscopy image reconstruction of PCV2d VLP at 3.3 [A] resolution and compared it to the previously reported PCV2a and PCV2b structures. Differences between the CD and GH loops identify structural changes that accompany the emergence of PCV2b from PCV2a, and PCV2d from PCV2b. We also model additional amino acids for the N-terminus near the icosahedral 3-fold axes of symmetry and a tetranucleotide between the 5- and 2-fold axes of symmetry. To interpret the sequence diversity that defines the PCV2 genotypes on a structural platform we have performed structure-based sequence comparison. Our analysis demonstrates that each genotype possesses a unique set of amino acids located on the surface of the capsid that experience a high degree of substitution. These substitutions may be a response to the PCV2 vaccination program. The structural difference between PCV2a, b and d genotypes indicate that it is important to determine the PCV2 capsid structure as the virus evolves into different genotypes.\n\nImportancePCV2 is a significant epidemic agricultural pathogen that is the causative agent of a variety of swine illnesses. PCV2 infections have significant economic impact in the swine industry and must be controlled by vaccination. Outbreaks in farms vaccinated for PCV2 suggest that improvements to the current vaccination programs are needed. Better understanding of the assembly, structure, replication and evolution of these viruses is necessary for production of improved vaccines. The ability of PCV2 to rapidly shift genotypes suggests that expression systems capable of rapidly producing large quantities of virus-like particles should be pursued. To these ends we have established a mammalian cell-based virus-like particle expression system and performed high resolution structural studies of a new PCV2 genotype. Differences between the structure of this genotype and earlier genotypes demonstrate that it is important to study the PCV2 structure as it shifts genotypes.

biophysics↗