Biology subjects

Earl, P. L.

Publications and source records attributed to Earl, P. L..

6 recordsLinked to original sources

bioRxiv2025

Antibody Binding and Neutralizing Targets within the Predicted Structure of the Poxvirus Multiprotein Entry-Fusion Complex

The increased incidence of mpox emphasizes a need for new and improved vaccines. Poxviruses rely on a highly conserved but poorly characterized 11-protein entry-fusion complex (EFC), providing numerous potential targets. Here, we demonstrate that antibodies induced by six of 10 EFC proteins are neutralizing. Protein targets of the neutralizing and non-neutralizing antibodies are located within discrete regions of a model of the EFC predicted by AlphaFold3. Two newly identified targets, A16 and G9, at the apex of the EFC induced cross-neutralizing orthopoxvirus antibodies and protected female mice against a lethal VACV infection. Unexpectedly, antibodies to A16 and G9 were not detected following infection by attenuated or pathogenic VACV, likely due to physical sequestration of the proteins in the viral membrane. Our findings provide a model for the physical, immunogenic and antigenic structure of the EFC, new immunogens for incorporation into recombinant vaccines and suggest a novel poxvirus immune evasion strategy. 150 words.

microbiology↗

bioRxiv2024

Mpox mRNA-1769 Vaccine Inhibits Orthopoxvirus Replication at Intranasal, Intrarectal, and Cutaneous Sites of Inoculation

The increasing incidence of mpox in Africa and the recent global outbreak with evidence of sexual transmission have stimulated interest in new vaccines and therapeutics. Our previous study demonstrated that mice immunized twice with a quadrivalent lipid nanoparticle vaccine comprising four monkeypox virus mRNAs raised neutralizing antibodies and antigen-specific T cells and were protected against a lethal intranasal challenge with vaccinia virus. Here we extended these findings by using live animal imaging to demonstrate that the mRNA vaccine greatly reduced virus replication and spread from an intranasal site of inoculation and prevented detectable replication at intrarectal and cutaneous inoculation sites. Moreover, considerable protection was achieved with a single vaccination and a booster vaccination enhanced protection for at least 4 months. Protection was related to the amount of mRNA inoculated, which correlated with neutralizing antibody levels. The role of antibody in protection was demonstrated by passive transfer of immune serum pre- or post-challenge to immunocompetent and immunodeficient mice lacking mature B and T cells and therefore unable to mount an adaptive response. These findings provide insights into the mechanism and extent of mRNA vaccine induced protection of orthopoxviruses and support clinical testing.

microbiology↗

bioRxiv2022

A monkeypox mRNA-lipid nanoparticle vaccine targeting virus binding, entry, and transmission drives protection against lethal orthopoxviral challenge

Monkeypox virus (MPXV) caused a global outbreak in 2022, fueled by behaviorally-altered and enhanced human-to-human transmission. While smallpox vaccines were rapidly deployed to curb spread and disease among those at highest risk, breakthrough disease was noted after complete immunization. Given the imminent threat of additional zoonotic events as well as the virus evolving ability to drive human-to-human transmission, there is an urgent need for the development of a MPXV-specific vaccine that is able to also confer broad protection against evolving strains and related orthopoxviruses. Here, we demonstrate that an mRNA-lipid nanoparticle vaccine encoding a set of four highly conserved MPXV surface proteins involved in virus attachment, entry and transmission can induce MPXV-specific immunity and heterologous protection against a lethal vaccinia virus (VACV) challenge. Compared to Modified Vaccinia Virus Ankara (MVA), which forms the basis for the current MPXV vaccine, mRNA-vaccination generated superior neutralizing and cellular spread-inhibitory activities against MPXV and VACV as well as greater Fc-effector Th1-biased humoral immunity to the four MPXV antigens and the four VACV homologs. Single MPXV antigen mRNA vaccines provided partial protection against VACV challenge, while combinations of two, three or four MPXV antigen expressing mRNAs protected against disease-related weight loss and death. Remarkably, the cross-protection by multivalent MPXV mRNAs was superior to the homologous protection by MVA, associated with a combination of neutralizing and non-neutralizing antibody functions. These data reveal robust protection against VACV using an mRNA-based vaccine targeting four highly conserved viral surface antigens, linked to the induction of highly functional antibodies able to rapidly control viral infection.

immunology↗

bioRxiv2022

Enhanced Protection from SARS-CoV-2 Variants by MVA-Based Vaccines Expressing Matched or Mismatched S Proteins Administered Intranasally to hACE2 Mice

The continuous evolution of SARS-CoV-2 strains is contributing to the prolongation of the global pandemic. We previously reported the prevention or more rapid clearance of SARS-CoV-2 from the nasal turbinates and lungs of susceptible K18-hACE2 mice that had been vaccinated intranasally (IN) rather than intramuscularly (IM) with a recombinant MVA (rMVA) expressing a modified S protein of the ancestor SARS-CoV-2 strain. Here, we constructed additional rMVAs and pseudoviruses expressing modified S protein of SARS-CoV-2 variants and compared the ability of vaccines with S proteins that were matched or mismatched to neutralize variants, bind to S proteins and protect K18-hACE2 mice against SARS-CoV-2 challenge. Although vaccines with matched S proteins induced higher neutralizing antibodies, vaccines with mismatched S proteins still protected against severe disease and reduced virus and mRNAs in the lungs and nasal turbinates, though not as well as vaccines with matched S proteins. In mice earlier primed and boosted with rMVA expressing ancestral S, antibodies to the latter increased after one immunization with rMVA expressing Omicron S, but neutralizing antibody to Omicron required a second immunization. Passive transfer of Wuhan immune serum with Omicron S binding but undetectable neutralizing activities reduced infection of the lungs by the variant. Notably, the reduction in infection of the nasal turbinates and lungs was significantly greater when the rMVAs were administered IN rather than IM and this held true for vaccines that were matched or mismatched to the challenge SARS-CoV-2.

microbiology↗

bioRxiv2022

Virulence Differences of Monkeypox Virus Clades 1, 2a and 2b.1 in a Small Animal Model

Human monkeypox, a disease with similarities to smallpox, is endemic in Africa where it has persisted as a zoonosis with limited human-to-human spread. Unexpectedly, the disease expanded globally in 2022 driven by human-to-human transmission outside of Africa. It is not yet known whether the latter is due solely to behavioral and environmental factors or whether the monkeypox virus is adapting to a new host. Genome sequencing has revealed differences between the current outbreak strains, classified as clade 2b, and the prior clade 2a and clade 1 viruses but whether these differences contribute to virulence or transmission has not been determined. We demonstrate that the wild-derived inbred CAST/EiJ mouse provides an exceptional animal model for investigating clade differences in monkeypox virus virulence and show that the order is clade 1 > clade 2a > clade 2b.1. The greatly reduced replication of the clade 2b.1 major outbreak strain in mice and absence of lethality at 100-times the lethal dose of a closely related clade 2a virus, despite similar multiplication in cell culture, suggest that clade 2b is evolving diminished virulence or adapting to other species. SIGNIFICANCEThree clades of monkeypox virus are recognized: clade 1 is present in the Congo Basin, causes 10% human mortality and is transmitted by rodents with little human-to-human spread; clade 2a exists in West Africa, has a low mortality and is also a zoonosis; clade 2b is currently spreading globally by human transmission. The genetic basis for differences in virulence and transmission have not been determined. A major roadblock is the need for a small animal model that can be studied under the stringent safety conditions required. Here we demonstrate that the three clades exhibit highly significant differences in CAST/EiJ mice in the order clade 1 > clade 2a > clade 2b, similar to the severity of clinical disease.

microbiology↗

bioRxiv2021

MVA Vector Vaccines Inhibit SARS CoV-2 Replication in Upper and Lower Respiratory Tracts of Transgenic Mice and Prevent Lethal Disease

Replication-restricted modified vaccinia virus Ankara (MVA) is a licensed smallpox vaccine and numerous clinical studies investigating recombinant MVAs (rMVAs) as vectors for prevention of other infectious diseases have been completed or are in progress. Two rMVA COVID-19 vaccine trials are at an initial stage, though no animal protection studies have been reported. Here, we characterize rMVAs expressing the S protein of CoV-2. Modifications of full length S individually or in combination included two proline substitutions, mutations of the furin recognition site and deletion of the endoplasmic retrieval signal. Another rMVA in which the receptor binding domain (RBD) flanked by the signal peptide and transmembrane domains of S was also constructed. Each modified S protein was displayed on the surface of rMVA-infected human cells and was recognized by anti-RBD antibody and by soluble hACE2 receptor. Intramuscular injection of mice with the rMVAs induced S-binding and pseudovirus-neutralizing antibodies. Boosting occurred following a second homologous rMVA but was higher with adjuvanted purified RBD protein. Weight loss and lethality following intranasal infection of transgenic hACE2 mice with CoV-2 was prevented by one or two immunizations with rMVAs or by passive transfer of serum from vaccinated mice. One or two rMVA vaccinations also prevented recovery of infectious CoV-2 from the lungs. A low amount of virus was detected in the nasal turbinates of only one of eight rMVA-vaccinated mice on day 2 and none later. Detection of subgenomic mRNA in turbinates on day 2 only indicated that replication was abortive in immunized animals. SignificanceVaccines are required to control COVID-19 during the pandemic and possibly afterwards. Recombinant nucleic acids, proteins and virus vectors that stimulate immune responses to the CoV-2 S protein have provided protection in experimental animal or human clinical trials, though questions remain regarding their ability to prevent spread and the duration of immunity. The present study focuses on replication-restricted modified vaccinia virus Ankara (MVA), which has been shown to be a safe, immunogenic and stable smallpox vaccine and a promising vaccine vector for other infectious diseases and cancer. In a transgenic mouse model, one or two injections of recombinant MVAs that express modified forms of S inhibited CoV-2 replication in the upper and lower respiratory tracts and prevented severe disease.

microbiology↗