Mapping immunodominant sites on the MERS-CoV spike glycoprotein targeted by infection-elicited antibodies in humans

Middle-East respiratory syndrome coronavirus (MERS-CoV) first emerged in 2012 and causes human infections in endemic regions. Most vaccines and therapeutics in development against MERS-CoV focus on the spike (S) glycoprotein to prevent viral entry into target cells. These efforts, however, are limited by a poor understanding of antibody responses elicited by infection along with their durability, fine specificity and contribution of distinct S antigenic sites to neutralization. To address this knowledge gap, we analyzed S-directed binding and neutralizing antibody titers in plasma collected from individuals infected with MERS-CoV in 2017-2019 (prior to the COVID-19 pandemic). We observed that binding and neutralizing antibodies peak 1 to 6 weeks after symptom onset/hospitalization, persist for at least 6 months, and broadly neutralize human and camel MERS-CoV strains. We show that the MERS-CoV S1 subunit is immunodominant and that antibodies targeting S1, particularly the RBD, account for most plasma neutralizing activity. Antigenic site mapping revealed that polyclonal plasma antibodies frequently target RBD epitopes, particularly a site exposed irrespective of the S trimer conformation, whereas targeting of S2 subunit epitopes is rare, similar to SARS-CoV-2. Our data reveal in unprecedented details the humoral immune responses elicited by MERS-CoV infection, which will guide vaccine and therapeutic design.

Type I interferon autoantibodies in hospitalized patients with Middle East respiratory syndrome and association with outcomes and treatment effect of interferon beta‐1b in MIRACLE clinical trial

Background

Type I interferons (IFNs) are essential antiviral cytokines induced upon respiratory exposure to coronaviruses. Defects in type I IFN signaling can result in severe disease upon exposure to respiratory viral infection and are associated with worse clinical outcomes. Neutralizing autoantibodies (auto‐Abs) to type I IFNs were reported as a risk factor for life‐threatening COVID‐19, but their presence has not been evaluated in patients with severe Middle East respiratory syndrome (MERS).

Methods

We evaluated the prevalence of type I IFN auto‐Abs in a cohort of hospitalized patients with MERS who were enrolled in a placebo‐controlled clinical trial for treatment with IFN‐β1b and lopinavir‐ritonavir (MIRACLE trial). Samples were tested for type I IFN auto‐Abs using a multiplex particle‐based assay.

Results

Among the 62 enrolled patients, 15 (24.2%) were positive for immunoglobulin G auto‐Abs for at least one subtype of type I IFNs. Auto‐Abs positive patients were not different from auto‐Abs negative patients in age, sex, or comorbidities. However, the majority (93.3%) of patients who were auto‐Abs positive were critically ill and admitted to the ICU at the time of enrollment compared to 66% in the auto‐Abs negative patients. The effect of treatment with IFN‐β1b and lopinavir‐ritonavir did not significantly differ between the two groups.

Conclusion

This study demonstrates the presence of type I IFN auto‐Abs in hospitalized patients with MERS.

Heterogeneity of treatment effect of interferon-β1b and lopinavir-ritonavir in patients with Middle East respiratory syndrome by cytokine levels

Animal and human data indicate variable effects of interferons in treating coronavirus infections according to inflammatory status and timing of therapy. In this sub-study of the MIRACLE trial (MERS-CoV Infection Treated with a Combination of Lopinavir-Ritonavir and Interferon β-1b), we evaluated the heterogeneity of treatment effect of interferon-β1b and lopinavir-ritonavir versus placebo among hospitalized patients with MERS on 90-day mortality, according to cytokine levels and timing of therapy. We measured plasma levels of 17 cytokines at enrollment and tested the treatment effect on 90-day mortality according to cytokine levels (higher versus lower levels using the upper tertile (67%) as a cutoff point) and time to treatment (≤ 7 days versus > 7 days of symptom onset) using interaction tests. Among 70 included patients, 32 received interferon-β1b and lopinavir-ritonavir and 38 received placebo. Interferon-β1b and lopinavir-ritonavir reduced mortality in patients with lower IL-2, IL-8 and IL-13 plasma concentrations but not in patients with higher levels (p-value for interaction = 0.09, 0.07, and 0.05, respectively) and with early but not late therapy (p = 0.002). There was no statistically significant heterogeneity of treatment effect according to other cytokine levels. Further work is needed to evaluate whether the assessment of inflammatory status can help in identifying patients with MERS who may benefit from interferon-β1b and lopinavir-ritonavir. Trial registration: This is a sub-study of the MIRACLE trial (ClinicalTrials.gov number, NCT02845843).

Interferon Beta-1b and Lopinavir-Ritonavir for Middle East Respiratory Syndrome

BACKGROUND

Whether combined treatment with recombinant interferon beta-1b and lopinavir-ritonavir reduces mortality among patients hospitalized with Middle East respiratory syndrome (MERS) is unclear.

METHODS

We conducted a randomized, adaptive, double-blind, placebo-controlled trial that enrolled patients at nine sites in Saudi Arabia. Hospitalized adults with laboratory-confirmed MERS were randomly assigned to receive recombinant interferon beta-1b plus lopinavir-ritonavir (intervention) or placebo for 14 days. The primary outcome was 90-day all-cause mortality, with a one-sided P-value threshold of 0.025. Prespecified subgroup analyses and safety analyses were conducted. Because of the pandemic of coronavirus disease 2019, the data and safety monitoring board requested an unplanned interim analysis and subsequently recommended the termination of enrollment and the reporting of the results.

RESULTS

A total of 95 patients were enrolled; 43 patients were assigned to the intervention group and 52 to the placebo group. A total of 12 patients (28%) in the intervention group and 23 (44%) in the placebo group died by day 90. The analysis of the primary outcome, with accounting for the adaptive design, yielded a risk difference of -19 percentage points (upper boundary of the 97.5% confidence interval [CI], -3; one-sided P = 0.024). In a prespecified subgroup analysis, treatment within 7 days after symptom onset led to lower 90-day mortality than use of placebo (relative risk, 0.19; 95% CI, 0.05 to 0.75), whereas later treatment did not. Serious adverse events occurred in 4 patients (9%) in the intervention group and in 10 (19%) in the placebo group.

CONCLUSIONS

A combination of recombinant interferon beta-1b and lopinavir-ritonavir led to lower mortality than placebo among patients who had been hospitalized with laboratory-confirmed MERS. The effect was greatest when treatment was started within 7 days after symptom onset. (Funded by the King Abdullah International Medical Research Center; MIRACLE ClinicalTrials.gov number, NCT02845843.).

Treatment of Middle East respiratory syndrome with a combination of lopinavir/ritonavir and interferon-β1b (MIRACLE trial): statistical analysis plan for a recursive two-stage group sequential randomized controlled trial

The MIRACLE trial (MERS-CoV Infection tReated with A Combination of Lopinavir/ritonavir and intErferon-β1b) investigates the efficacy of a combination therapy of lopinavir/ritonavir and recombinant interferon-β1b provided with standard supportive care, compared to placebo provided with standard supportive care, in hospitalized patients with laboratory-confirmed MERS. The MIRACLE trial is designed as a recursive, two-stage, group sequential, multicenter, placebo-controlled, double-blind randomized controlled trial. The aim of this article is to describe the statistical analysis plan for the MIRACLE trial. The primary outcome is 90-day mortality. The primary analysis will follow the intention-to-treat principle. The MIRACLE trial is the first randomized controlled trial for MERS treatment. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02845843. Registered on 27 July 2016.

Evaluation of visual triage for screening of Middle East respiratory syndrome coronavirus patients

The emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in September 2012 in Saudi Arabia had attracted the attention of the global health community. In 2017 the Saudi Ministry of Health released a visual triage system with scoring to alert healthcare workers in emergency departments (EDs) and haemodialysis units for the possibility of occurrence of MERS-CoV infection. We performed a retrospective analysis of this visual score to determine its sensitivity and specificity. The study included all cases from 2014 to 2017 in a MERS-CoV referral centre in Riyadh, Saudi Arabia. During the study period there were a total of 2435 suspected MERS cases. Of these, 1823 (75%) tested negative and the remaining 25% tested positive for MERS-CoV by PCR assay. The application of the visual triage score found a similar percentage of MERS-CoV and non–MERS-CoV patients, with each score from 0 to 11. The percentage of patients with a cutoff score of ≥4 was 75% in patients with MERS-CoV infection and 85% in patients without MERS-CoV infection (p 0.0001). The sensitivity and specificity of this cutoff score for MERS-CoV infection were 74.1% and 18.6%, respectively. The sensitivity and specificity of the scoring system were low, and further refinement of the score is needed for better prediction of MERS-CoV infection.