Serum Neutralizing Activity of mRNA-1273 against SARS-CoV-2 Variants

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has led to growing concerns over increased transmissibility and the ability of some variants to partially escape immunity. Sera from participants immunized on a prime-boost schedule with the mRNA-1273 COVID-19 vaccine were tested for neutralizing activity against several SARS-CoV-2 variants, including variants of concern (VOCs) and variants of interest (VOIs), compared to neutralization of the wild-type SARS-CoV-2 virus (designated as D614G). Results showed minimal effects on neutralization titers against the B.1.1.7 (Alpha) variant (1.2-fold reduction compared with D614G); other VOCs such as B.1.351 (Beta, including B.1.351-v1, B.1.351-v2, and B.1.351-v3), B.1.617.2 (Delta), and P.1 (Gamma) showed decreased neutralization titers ranging from 2.1-fold to 8.4-fold reductions compared with D614G, although all remained susceptible to mRNA-1273-elicited serum neutralization.

Durability of mRNA-1273-induced antibodies against SARS-CoV-2 variants

SARS-CoV-2 mutations may diminish vaccine-induced protective immune responses, and the durability of such responses has not been previously reported. Here, we present a comprehensive assessment of the impact of variants B.1.1.7, B.1.351, P.1, B.1.429, and B.1.526 on binding, neutralizing, and ACE2-blocking antibodies elicited by the vaccine mRNA-1273 over seven months. Cross-reactive neutralizing responses were rare after a single dose of mRNA-1273. At the peak of response to the second dose, all subjects had robust responses to all variants. Binding and functional antibodies against variants persisted in most subjects, albeit at low levels, for 6 months after the primary series of mRNA-1273. Across all assays, B.1.351 had the greatest impact on antibody recognition, and B.1.1.7 the least. These data complement ongoing studies of clinical protection to inform the potential need for additional boost vaccinations. One-Sentence SummaryMost mRNA-1273 vaccinated individuals maintained binding and functional antibodies against SARS-CoV-2 variants for 6 months.

Preliminary Analysis of Safety and Immunogenicity of a SARS-CoV-2 Variant Vaccine Booster

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of a global pandemic of coronavirus disease 2019 (COVID-19) that has led to more than 3 million deaths worldwide. Safe and effective vaccines are now available, including the mRNA-1273 prototype vaccine, which encodes for the Wuhan SARS-CoV-2 spike (S) protein stabilized in the prefusion conformation by 2 proline substitutions. This vaccine showed 94% efficacy in prevention of symptomatic COVID-19 disease in a phase 3 clinical study. Recently, SARS-CoV-2 variants have emerged, some of which have shown decreased susceptibility to neutralization by vaccine-induced antibody, most notably the B.1.351 variant, although the overall impact on vaccine efficacy remains to be determined. In addition, recent evidence of waning antibody levels after infection or vaccination point to the need for periodic boosting of immunity. Here we present the preliminary evaluation of a clinical study on the use of the prototype mRNA-1273 or modified COVID-19 mRNA vaccines, designed to target emerging SARS-CoV-2 variants as booster vaccines in participants previously vaccinated approximately 6 months earlier with two doses of the prototype vaccine, mRNA-1273. The modified vaccines include a monovalent mRNA-1273.351 encoding for the S protein found in the B.1.351 variant and multivalent mRNA-1273.211 comprising a 1:1 mix of mRNA-1273 and mRNA-1273.351. As single 50 {micro}g booster vaccinations, both mRNA-1273 and mRNA-1273.351 had acceptable safety profiles and were immunogenic. Antibody neutralization titers against B.1.351 and P.1 variants measured by SARS-CoV-2 pseudovirus neutralization (PsVN) assays before the booster vaccinations, approximately 6 to 8 months after the primary series, were low or below the assay limit of quantification, although geometric mean titers versus the wild-type strain remained above levels likely to be protective. Two weeks after the booster vaccinations, titers against the wild-type original strain, B.1.351, and P.1 variants increased to levels similar to or higher than peak titers after the primary series vaccinations. Although both mRNA-1273 and mRNA-1273.351 boosted neutralization of the wild-type original strain, and B.1.351 and P.1 variants, mRNA-1273.351 appeared to be more effective at increasing neutralization of the B.1.351 virus versus a boost with mRNA-1273. The vaccine trial is ongoing and boosting of clinical trial participants with the multivalent mRNA-1273.211 is currently being evaluated.

Variant SARS-CoV-2 mRNA vaccines confer broad neutralization as primary or booster series in mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of a global pandemic. Safe and effective COVID-19 vaccines are now available, including mRNA-1273, which has shown 94% efficacy in prevention of symptomatic COVID-19 disease. However, the emergence of SARS-CoV-2 variants has led to concerns of viral escape from vaccine-induced immunity. Several variants have shown decreased susceptibility to neutralization by vaccine-induced immunity, most notably B.1.351 (Beta), although the overall impact on vaccine efficacy remains to be determined. Here, we present the initial evaluation in mice of 2 updated mRNA vaccines designed to target SARS-CoV-2 variants: (1) monovalent mRNA-1273.351 encodes for the spike protein found in B.1.351 and (2) mRNA-1273.211 comprising a 1:1 mix of mRNA-1273 and mRNA-1273.351. Both vaccines were evaluated as a 2-dose primary series in mice; mRNA-1273.351 was also evaluated as a booster dose in animals previously vaccinated with mRNA-1273. The results demonstrated that a primary vaccination series of mRNA-1273.351 was effective at increasing neutralizing antibody titers against B.1.351, while mRNA-1273.211 was effective at providing broad cross-variant neutralization. A third (booster) dose of mRNA-1273.351 significantly increased both wild-type and B.1.351-specific neutralization titers. Both mRNA-1273.351 and mRNA-1273.211 are being evaluated in pre-clinical challenge and clinical studies.

mRNA-1273 vaccine induces neutralizing antibodies against spike mutants from global SARS-CoV-2 variants

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative infection of a global pandemic that has led to more than 2 million deaths worldwide. The Moderna mRNA-1273 vaccine has demonstrated ~94% efficacy in a Phase 3 study and has been approved under Emergency Use Authorization. The emergence of SARS-CoV-2 variants with mutations in the spike protein, most recently circulating isolates from the United Kingdom (B.1.1.7) and Republic of South Africa (B.1.351), has led to lower neutralization from convalescent serum by pseudovirus neutralization (PsVN) assays and resistance to certain monoclonal antibodies. Here, using two orthogonal VSV and lentivirus PsVN assays expressing spike variants of 20E (EU1), 20A.EU2, D614G-N439, mink cluster 5, B.1.1.7, and B.1.351 variants, we assessed the neutralizing capacity of sera from human subjects or non-human primates (NHPs) that received mRNA-1273. No significant impact on neutralization against the B.1.1.7 variant was detected in either case, however reduced neutralization was measured against the mutations present in B.1.351. Geometric mean titer (GMT) of human sera from clinical trial participants in VSV PsVN assay using D614G spike was 1/1852. VSV pseudoviruses with spike containing K417N-E484K-N501Y-D614G and full B.1.351 mutations resulted in 2.7 and 6.4-fold GMT reduction, respectively, when compared to the D614G VSV pseudovirus. Importantly, the VSV PsVN GMT of these human sera to the full B.1.351 spike variant was still 1/290, with all evaluated sera able to fully neutralize. Similarly, sera from NHPs immunized with 30 or 100g of mRNA-1273 had VSV PsVN GMTs of ~ 1/323 or 1/404, respectively, against the full B.1.351 spike variant with a ~ 5 to 10-fold reduction compared to D614G. Individual mutations that are characteristic of the B.1.1.7 and B.1.351 variants had a similar impact on neutralization when tested in VSV or in lentivirus PsVN assays. Despite the observed decreases, the GMT of VSV PsVN titers in human vaccinee sera against the B.1.351 variant remained at ~1/300. Taken together these data demonstrate reduced but still significant neutralization against the full B.1.351 variant following mRNA-1273 vaccination.

SARS-CoV-2 mRNA Vaccine Development Enabled by Prototype Pathogen Preparedness

A SARS-CoV-2 vaccine is needed to control the global COVID-19 public health crisis. Atomic-level structures directed the application of prefusion-stabilizing mutations that improved expression and immunogenicity of betacoronavirus spike proteins. Using this established immunogen design, the release of SARS-CoV-2 sequences triggered immediate rapid manufacturing of an mRNA vaccine expressing the prefusion-stabilized SARS-CoV-2 spike trimer (mRNA-1273). Here, we show that mRNA-1273 induces both potent neutralizing antibody and CD8 T cell responses and protects against SARS-CoV-2 infection in lungs and noses of mice without evidence of immunopathology. mRNA-1273 is currently in a Phase 2 clinical trial with a trajectory towards Phase 3 efficacy evaluation.

Clinical presentation, magnetic resonance imaging features, and outcome in 6 cats with lumbar degenerative intervertebral disc extrusion treated with hemilaminectomy.

OBJECTIVE: To describe the clinical presentation, magnetic resonance imaging features, and outcome of cats treated with hemilaminectomy for intervertebral disc extrusion (IVDE). STUDY DESIGN: Short case series. ANIMALS: Six cats. METHODS: Medical records were reviewed for signalment, onset, duration, and severity of clinical signs, magnetic resonance imaging features, surgical findings, and clinical outcome with a minimum postoperative follow-up of 4 weeks. RESULTS: Our population included 6 cats with a median age of 8.6 years, consisting predominantly of males (n = 5) and purebred cats (n = 4). An acute onset and short duration of progressive clinical signs of myelopathy was the most common presentation; spinal hyperesthesia was present in 3 cats. A large volume of extradural material was identified by MRI within the lumbar vertebral column of each cat, causing marked spinal cord compression. The most common sites affected were L2-L3 (n = 2) and L6-L7 (n = 2). Follow-up after hemilaminectomy was available in 5 cats: 4 had normal voluntary motor function, and 1 had recurrence of acute paraplegia, compromised nociception, and an extensive T2w hyperintense intramedullary lesion according to MRI. All 4 cats with preoperative urinary incontinence remained incontinent for at least 1 week despite good voluntary motor function of pelvic limbs. CONCLUSION: Intervertebral disc extrusion was diagnosed by MRI in all 6 cats, most commonly at L2-3 and L6-7. Hemilaminectomy resulted in a good to excellent outcome in 4 of 5 cats. CLINICAL SIGNIFICANCE: Feline IVDE can be diagnosed by MRI and carry a good prognosis after surgical decompression, although urinary continence may be delayed despite good pelvic limb voluntary motor function.

Accuracy of a patient-specific 3D printed drill guide for placement of cervical transpedicular screws.

OBJECTIVE: To develop a patient-specific 3-dimensional (3D) printed drill guide for placement of cervical transpedicular screws and to assess its accuracy. STUDY DESIGN: Prospective case-series. SAMPLE POPULATION: Thirty-two cervical pedicle screws (CPS) placed in 3 large breed dogs. METHODS: Computed tomographic (CT) data of the cervical vertebrae were exported to a medical image processing software and 3D virtual vertebral models were created for each vertebra. These models were processed in a computer aided design (CAD) software to determine the optimal trajectory and size of the CPS. Virtual drill guides were created for each patient, 3D-printed, and used intraoperatively. Locking titanium screw heads were bonded with polymethylmethacrylate cement to stabilize affected vertebral segments. Postoperative CT was used to assess the radiological accuracy of CPS placement in each dog. For each screw, CAD files were analyzed to determine a screw-diameter-to-pedicle-width-ratio (SDPWR) at the narrowest point of the pedicle. RESULTS: A total of 32 CPS were placed, measuring 3.5 mm (n = 20), 2.7 mm (n = 11), and 2.4 mm (n = 1) in diameter. The majority (29/32) of these screws were placed without evidence of vertebral canal breach (grade 0), whereas a vertebral canal breach <2 mm (grade 1) was detected in 3/32 screws. This outcome was achieved despite a mean SDPWR of 0.75 (range 0.58-0.93). CONCLUSION: The use of a 3D-printed patient-specific drill guide permitted accurate placement of 32 bicortical pedicle screws in the caudal cervical vertebrae of 3 dogs. This technique may improve clinical outcome through superior biomechanical properties of screws, reduced surgical time, and reduced morbidity. These results warrant evaluation of patient outcome in a larger population.