Superior immunogenicity of mRNA over adenoviral vectored COVID-19 vaccines reflects B cell dynamics independent of anti-vector immunity: Implications for future pandemic vaccines.

Both vector and mRNA vaccines were an important part of the response to the COVID-19 pandemic and may be required in future outbreaks and pandemics. The aim of this study was to validate whether immunogenicity differs for adenoviral vectored (AdV) versus mRNA vaccines against SARS-CoV-2, and to investigate how anti-vector immunity and B cell dynamics modulate immunogenicity. We enrolled SARS-CoV-2 infection-naïve health care workers who had received two doses of either AdV AZD1222 (n = 184) or mRNA BNT162b2 vaccine (n = 274) between April and October 2021. Blood was collected at least once, 10-48 days after vaccine dose 2 for antibody and B cell analyses. Median ages were 42 and 39 years, for AdV and mRNA vaccinees, respectively. Surrogate virus neutralization test (sVNT) and spike binding antibody titres were a median of 4.2 and 2.2 times lower, respectively, for AdV compared to mRNA vaccinees (p < 0.001). Median percentages of memory B cells that recognized fluorescent-tagged spike and RBD were 2.9 and 8.3 times lower, respectively for AdV compared to mRNA vaccinees. Titres of IgG reactive with human adenovirus type 5 hexon protein rose a median of 2.2-fold after AdV vaccination but were not correlated with anti-spike antibody titres. Together the results show that mRNA induced substantially more sVNT antibody than AdV vaccine, which reflected greater B cell expansion and targeting of the RBD rather than an attenuating effect of anti-vector antibodies. ClinicalTrials.gov Identifier: NCT05110911.

Comparative B cell and antibody responses induced by adenoviral vectored and mRNA vaccines against COVID-19.

Both vector and mRNA vaccines were an important part of the response to the COVID-19 pandemic and may be required in future outbreaks and pandemics. However, adenoviral vectored (AdV) vaccines may be less immunogenic than mRNA vaccines against SARS-CoV-2. We assessed anti-spike and anti-vector immunity among infection-naïve Health Care Workers (HCW) following two doses of AdV (AZD1222) versus mRNA (BNT162b2) vaccine. 183 AdV and 274 mRNA vaccinees enrolled between April and October 2021. Median ages were 42 and 39 years, respectively. Blood was collected at least once, 10-48 days after vaccine dose 2. Surrogate virus neutralization test (sVNT) and spike binding antibody titres were a median of 4.2 and 2.2 times lower, respectively, for AdV compared to mRNA vaccinees (p<0.001). Median percentages of memory B cells that recognized fluorescent-tagged spike and RBD were 2.9 and 8.3 times lower, respectively for AdV compared to mRNA vaccinees. Titres of IgG reactive with human Adenovirus type 5 hexon protein rose a median of 2.2-fold after AdV vaccination but were not correlated with anti-spike antibody titres. Together the results show that mRNA induced substantially more sVNT antibody than AdV vaccine due to greater B cell expansion and targeting of the RBD. Pre-existing AdV vector cross-reactive antibodies were boosted following AdV vaccination but had no detectable effect on immunogenicity.

Favipiravir in early symptomatic COVID-19, a randomised placebo-controlled trial.

Background: Well tolerated antivirals administered early in the course of COVID-19 infection when the viremia is highest could prevent progression to severe disease. Favipiravir inhibits SARS-CoV-2 viral replication in vitro with evidence of clinical benefit in open label trials. Placebo controlled studies of people with early symptomatic COVID-19 with regular assessments of SARS-CoV-2 viral load can determine if it has an antiviral effect and improves clinical outcomes. Methods: People with PCR-confirmed COVID-19 and 5 days or less of symptoms were randomised 1:1 to favipiravir 1800 mg on day 1, then 800 mg twice daily or matched placebo for 14 days. SARS-CoV-2 viral load was quantitated from second daily self-collected nose-throat swabs while receiving study drug. The primary endpoint was time to virological cure defined as 2 successive swabs negative for SARS-CoV-2 by PCR and secondary outcomes were progression of disease severity, symptom resolution and safety. Findings: Between 31 July 2020 and 19 September 2021, 200 people were enrolled (199 in the community, 1 in hospital) with 190 receiving one or more doses of drug (modified intention to treat [mITT] population). There was no difference in time to virological cure (Log-rank p=0.6 comparing Kaplan Meier curves), progression to hospitalisation (14 favipiravir, 9 placebo; p=0.38), time to symptom resolution (cough, fever, sore throat) and there were no deaths. 51 people related an adverse event that was possibly drug related, but these were evenly distributed (n=24 favipiravir, n=27 placebo). Sensitivity analyses where the definition of virological cure was changed to: a single negative PCR, exclude datapoints based on the presence or absence of human DNA in the swab, a SARS-CoV-2 viral load < 300 copies/mL being considered negative all demonstrated no difference between arms. Interpretation: Favipiravir does not improve the time to virological cure or clinical outcomes and shows no evidence of an antiviral effect when treating early symptomatic COVID-19 infection. Funding: The study was supported in part by grants from the Commonwealth Bank Australia, the Lord Mayor's Charitable Foundation, Melbourne Australia and the Orloff Family Charitable Trust, Melbourne, Australia. JHM is supported by the Medical Research Future Fund, AYP, JT are supported by the Australian National Health and Medical Research Council.

Neurotoxicity with high-dose disulfiram and vorinostat used for HIV latency reversal.

OBJECTIVE: The aim of this study was to examine whether administering both vorinostat and disulfiram to people with HIV (PWH) on antiretroviral therapy (ART) is well tolerated and can enhance HIV latency reversal. DESIGN: Vorinostat and disulfiram can increase HIV transcription in PWH on ART. Together, these agents may lead to significant HIV latency reversal. METHODS: Virologically suppressed PWH on ART received disulfiram 2000 mg daily for 28 days and vorinostat 400 mg daily on days 8-10 and 22-24. The primary endpoint was plasma HIV RNA on day 11 relative to baseline using a single copy assay. Assessments included cell-associated unspliced RNA as a marker of latency reversal, HIV DNA in CD4+ T-cells, plasma HIV RNA, and plasma concentrations of ART, vorinostat, and disulfiram. RESULTS: The first two participants (P1 and P2) experienced grade 3 neurotoxicity leading to trial suspension. After 24 days, P1 presented with confusion, lethargy, and ataxia having stopped disulfiram and ART. Symptoms resolved by day 29. After 11 days, P2 presented with paranoia, emotional lability, lethargy, ataxia, and study drugs were ceased. Symptoms resolved by day 23. CA-US RNA increased by 1.4-fold and 1.3-fold for P1 and P2 respectively. Plasma HIV RNA was detectable from day 8 to 37 (peak 81 copies ml-1) for P2 but was not increased in P1 Antiretroviral levels were therapeutic and neuronal injury markers were elevated in P1. CONCLUSION: The combination of prolonged high-dose disulfiram and vorinostat was not safe in PWH on ART and should not be pursued despite evidence of latency reversal.

A clinical trial of non-invasive imaging with an anti-HIV antibody labelled with copper-64 in people living with HIV and uninfected controls.

BACKGROUND: A research priority in finding a cure for HIV is to establish methods to accurately locate and quantify where and how HIV persists in people living with HIV (PLWH) receiving suppressive antiretroviral therapy (ART). Infusing copper-64 (64Cu) radiolabelled broadly neutralising antibodies targeting HIV envelope (Env) with CT scan and positron emission tomography (PET) identified HIV Env in tissues in SIV infected non-human primates . We aimed to determine if a similar approach was effective in people living with HIV (PLWH). METHODS: Unmodified 3BNC117 was compared with 3BNC117 bound to the chelator MeCOSar and 64Cu (64Cu-3BNC117) in vitro to assess binding and neutralization. In a clinical trial 64Cu-3BNC117 was infused into HIV uninfected (Group 1), HIV infected and viremic (viral load, VL >1000 c/mL; Group 2) and HIV infected aviremic (VL <20 c/mL; Group 3) participants using two dosing strategies: high protein (3mg/kg unlabeled 3BNC117 combined with <5mg 64Cu-3BNC117) and trace (<5mg 64Cu-3BNC117 only). All participants were screened for 3BNC117 sensitivity from virus obtained from viral outgrowth. Magnetic resonance imaging (MRI)/PET and pharmacokinetic assessments (ELISA for serum 3BNC117 concentrations and gamma counting for 64Cu) were performed 1, 24- and 48-hours post dosing. The trial (clincialtrials.gov NCT03063788) primary endpoint was comparison of PET standard uptake values (SUVs) in regions of interest (e.g lymph node groups and gastrointestinal tract). FINDINGS: Comparison of unmodified and modified 3BNC117 in vitro demonstrated no difference in HIV binding or neutralisation. 17 individuals were enrolled of which 12 were dosed including Group 1 (n=4, 2 high protein, 2 trace dose), Group 2 (n=6, 2 high protein, 4 trace) and Group 3 (n=2, trace only). HIV+ participants had a mean CD4 of 574 cells/microL and mean age 43 years. There were no drug related adverse effects and no differences in tissue uptake in regions of interest (e.g lymph node gut, pharynx) between the 3 groups. In the high protein dosing group, serum concentrations of 3BNC117 and gamma counts were highly correlated demonstrating that 64Cu-3BNC117 remained intact in vivo. INTERPRETATION: In PLWH on or off ART, the intervention of infusing 64Cu-3BNC117 and MRI/PET imaging over 48 hours, was unable to detect HIV-1 env expression in vivo. Future studies should investigate alternative radiolabels such as zirconium which have a longer half-life in vivo. FUNDING: Funded by the Alfred Foundation, The Australian Centre for HIV and Hepatitis Virology Research with additional support from the Division of AIDS, National Institute of Allergy and Infectious Disease, US National Institutes of Health (USAI126611). JHM and SRL are supported by the Australian National Health and Medical Research Council.

No adverse safety or virological changes 2 years following vorinostat in HIV-infected individuals on antiretroviral therapy.

OBJECTIVE: To determine the long-term effects of vorinostat on safety and virological parameters in HIV-infected individuals on suppressive antiretroviral therapy (ART). DESIGN: Prospective longitudinal observational extended follow-up of 20 HIV-infected individuals on ART previously enrolled in a clinical trial of daily vorinostat 400 mg for 14 days. Extended follow-up included visits at 6, 12, 18 and 24 months postenrolment in the initial clinical trial. METHODS: Cell-associated unspliced HIV RNA, total HIV DNA and plasma HIV RNA were quantified by PCR, and CD4 and CD8 T cells quantified by flow cytometry. Changes over time in each parameter were assessed using the Wilcoxon matched pair signed-rank test and generalized estimating equations for trend modelling. RESULTS: We recorded a total of 31 adverse events (26 grade 1 and five grade 2) in all study participants (n = 20). There were no significant changes in the number of CD4 or CD8 T cells or plasma HIV RNA over time. In 12 participants for whom baseline samples were available, there were no significant changes in total HIV DNA, cell-associated unspliced HIV RNA, plasma RNA or CD4 and CD8 T cells at 6, 12, 18 or 24 months. CONCLUSION: Extended follow-up for 24 months did not reveal any long-term toxicity or changes in markers of HIV persistence or transcription in participants on ART who had received 14 days of vorinostat.