ABSTRACT
Background: Currently available COVID-19 vaccination regimens in the US deliver either a homologous spike (S) mRNA prime-boost or a prime-only S DNA adenovirus-vectored antigen to elicit humoral and cell-mediated responses to confer protection against SAR-CoV-2 infection. Alternatively, heterologous vaccination using two different platforms has the potential to enhance and expand immune protection. Addition of a second SARS-CoV-2 antigen, the nucleocapsid (N) protein that is less subject to mutation and elicits vigorous T-cell responses, may also be advantageous. We report immunological responses to homologous and heterologous prime-boost vaccination regimens with a human DNA adenovirus serotype 5 S plus N (AdS+N) and/or a self-amplifying S-only mRNA vaccine (AAAH) delivered with a nanostructured lipid carrier (NLC). Methods: CD-1 mice received homologous or heterologous prime-boost combinations of AdS+N and AAAH. Priming doses were administered on Day 0, booster doses were delivered on Day 21, and mice were euthanized for blood and organ collection on Day 35. Serum was analyzed for anti-S (both wild type and variant) and anti-N IgG subtypes by ELISA. Spleen-resident CD4+ and CD8+ T cells were tested for IFN-γ, TNF-α, and IL-2 production in response to S-WT, S Delta variant and N protein overlapping peptides by intracellular cytokine staining (ICS). Splenocyte cytokine secretion upon stimulation with S-WT/N peptides was also assessed by IFN-γ and IL-4 ELISpot. Serum neutralization of the original Wuhan strain, Delta, and B.1.351 variants was assessed by a pseudovirus neutralization assay. Results: The highest humoral and T-cell responses were seen with the heterologous AAAH prime-AdS+N boost regimen, with a significant increase in T-cell responses relative to homologous vaccination. S protein-binding IgG was similar between wild type and Delta variant S proteins, with a strong/clear Th1/Th2 bias, and T cells responded to S wild type and S Delta peptides with similar levels of cytokine expression. Sera from AAAH prime-AdS+N boost mice showed the ability to neutralize Wuhan D614G, Delta, and B.1.351 (South Africa) variant pseudoviruses at high levels. Conclusion: Heterologous vaccination with the AAAH RNA vaccine prime and an AdS+N DNA boost may provide substantially improved humoral and cell-based immunity against SARS-CoV-2 variants by leveraging the advantages of each vaccine platform technology and by inclusion of immune responses to N.
ABSTRACT
Low-Dose Radiation Therapy (LD-RT) is an emerging treatment option for patients with COVID-19 related pneumonia. Infectivity of the SARS-CoV-2 virus complicates incorporation of LD-RT into existing radiation oncology clinics. The first phase I/II trial of LD-RT for COVID-19-related pneumonia implemented novel operational protocols to address risk of infection and respiratory events. Patients were transported from hospital rooms to linear accelerators and treated with 0.5 Gy or 1.5 Gy using pre-planned, two-dimensional treatments prepared using diagnostic x-rays and caliper measurements. Workflows were revised over time to balance infection risks with implementation burden. Between April 24 and December 7, 2020, fifty-two patients were enrolled and forty were treated. The end-to-end process comprised 16 distinct teams and > 120 cooperating staff members (> 50 core radiation oncology staff). The trial was operationalized at two hospitals at the onset of the COVID-19 pandemic, prior to vaccine availability. Teams included trial leadership/screening (n > 4), inpatient floor staff (n > 10), clinical trials staff and coordinators (n = 8), transport (n = 2), radiation therapists (n > 20), respiratory therapists (n = 5), radiation nursing (n > 7), ICU nursing (n = 4), rapid response teams (n = 4), medical physics (n > 4), dosimetry (n > 3), infection prevention (n > 3), environmental services (n > 6), security (n = 7), lab personnel (n = 1), and physicians from radiation oncology (n = 7), infectious diseases (n = 2), pulmonary/critical care medicine (n = 2), anesthesia (n = 2), and internal medicine (n > 20) [total > 120]. All non-intubated patients were transported by a multi-disciplinary team, consisting of a physician, nurse, transporter, infection prevention specialist, and (when needed) a respiratory therapist. Treatments occurred after normal clinic hours, were initiated by team huddles, check lists, and included personal protective equipment supervision at multiple time points. Transport routes were 880 to 1760 feet (0.33 miles) one-way, with 1 to 3 elevator banks and required 20-35 minutes for round-trip transport and treatment. Oxygen supplementation in non-intubated patients ranged from 2 to 15 L/min. One intubated patient was transported with a portable ventilator and accompanying ICU staff. There were no code-level events during transport. No patient-facing staff contracted COVID-19 from trial activities. Workflow burden was successfully reduced and protocols relaxed over time with increased staff experience. Whole-lung low-dose radiation therapy (LD-RT) for COVID-19-related pneumonia was successfully incorporated into existing workflows at a major academic university. Forty patients were treated with no code-level events, and no staff contracted the virus during eight months of trial accrual. Instructional materials and implementation check lists are provided. [ABSTRACT FROM AUTHOR] Copyright of International Journal of Radiation Oncology, Biology, Physics is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)