Evaluation of Neutralizing Activity against Omicron Subvariants in BA.5 Breakthrough Infection and Three-Dose Vaccination Using a Novel Chemiluminescence-Based, Virus-Mediated Cytopathic Assay.

Neutralizing potency of humoral immune responses induced by prior infection or vaccination is vital for protecting of individuals and population against severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). However, the emergence of viral variants that can evade neutralization by vaccine- or infection-induced immunity is a significant public health threat and requires continuous monitoring. Here, we have developed a novel scalable chemiluminescence-based assay for assessing SARS-CoV-2-induced cytopathic effect to quantify the neutralizing activity of antisera. The assay leverages the correlation between host cell viability and ATP levels in culture to measure the cytopathic effect on target cells induced by clinically isolated, replication-competent, authentic SARS-CoV-2. With this assay, we demonstrate that the recently arisen Omicron subvariants BQ.1.1 and XBB.1 display a significant decrease in sensitivity to neutralization by antibodies elicited from breakthrough infections with Omicron BA.5 and from receipt of three doses of mRNA vaccines. Thus, this scalable neutralizing assay provides a useful platform to assess the potency of acquired humoral immunity against newly emerging SARS-CoV-2 variants. IMPORTANCE The ongoing global pandemic of SARS-CoV-2 has emphasized the importance of neutralizing immunity in protecting individuals and populations against severe respiratory illness. In light of the emergence of viral variants with the potential to evade immunity, continuous monitoring is imperative. A virus plaque reduction neutralization test (PRNT) is a "gold standard" assay for analyzing neutralizing activity for authentic viruses that form plaques, like influenza virus, dengue virus, and SARS-CoV-2. However, this method is labor intensive and is not efficient for performing large-scale neutralization assays on patient specimens. The assay system established in this study allows for the detection of a patient's neutralizing activity by simply adding an ATP detection reagent, providing a simple evaluation system for neutralizing activity of antisera as an alternative to the plaque reduction method. Our extended analysis of the Omicron subvariants highlights their increasing capability to evade neutralization by both vaccine- and infection-induced humoral immunity.

Immunosuppressive therapy and humoral response to third mRNA COVID-19 vaccination with a six-month interval in rheumatic disease patients.

OBJECTIVES: To evaluate the long-term impact of immunosuppressive therapeutic agents on antibody response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) mRNA vaccination in patients with autoimmune rheumatic diseases (AIRD) in order to propose a strategy for annual vaccination. METHODS: This prospective multicentre cohort study evaluated the humoral response to second and third BNT162b2 and/or mRNA-1273 vaccines in 382 Japanese AIRD patients classified into 12 different medication groups and in 326 healthy controls (HCs). The third vaccination was administered six months after the second vaccination. Antibody titres were measured using the Elecsys Anti-SARS-CoV-2 S assay. RESULTS: The seroconversion rate and antibody titres were lower in AIRD patients than in HCs 3-6 weeks after the second vaccination and 3-6 weeks after the third vaccination. Seroconversion rates were <90% after the third vaccination in patients receiving mycophenolate mofetil and rituximab. A multivariate analysis was conducted, adjusting for age, sex, and glucocorticoid dosage. Antibody levels after the third vaccination were significantly lower in the groups prescribed tumour necrosis factor (TNF) inhibitor with or without methotrexate, abatacept and rituximab or cyclophosphamide than those of HCs. The third vaccination induced an adequate humoral response in patients treated with sulfasalazine, bucillamine, methotrexate monotherapy, iguratimod, interleukin-6 inhibitors or calcineurin inhibitors including tacrolimus. CONCLUSIONS: Repeated vaccinations in many immunosuppressed patients produced antibody responses similar to those observed in HCs. In contrast, annual vaccination in patients receiving TNF inhibitors, abatacept, mycophenolate mofetil and rituximab may require caution.

Platypnea-Orthodeoxia Syndrome in Coronavirus Disease 2019 Pneumonia: A Case Report and Literature Review.

Platypnea-orthodeoxia syndrome (POS) is a rare disorder associated with coronavirus disease 2019 (COVID-19) pneumonia. However, POS may be underdiagnosed. We report the case of a 59-year-old female patient with POS complicated by pulmonary embolism in COVID-19. Imaging revealed ground-glass opacities predominantly in the lower lobes and a pulmonary embolus in the right upper lobe. She was diagnosed with POS due to marked postural discrepancies between supine and upright oxygen saturations and blood oxygenation. Intracardiac shunt, one of the etiologies of POS, was not detected by bubble contrast echocardiography, and postural de-saturation gradually improved with methylprednisolone and edoxaban administration. In our literature review, only 3 of the 16 patients with POS associated with COVID-19 had cardiac shunting, suggesting that moderate to severe COVID-19 causes POS without cardiac shunts. COVID-19-associated vasculopathy and lower lung lesion predominance in COVID-19 pneumonia may cause ventilation-perfusion mismatch due to gravitational shunting of blood into the poorly ventilated lower lungs in the upright position, which may ultimately cause POS. Hypoxemia impedes rehabilitation, whereas early initiation of supine positioning in bed, with knowledge of the pathophysiology of POS, may have a positive effect.

Pronounced antibody elevation after SARS-CoV-2 BNT162b2 mRNA booster vaccination in nursing home residents.

BACKGROUND: Infection control during COVID-19 outbreaks in nursing facilities is a critical public health issue. Antibody responses before and after the third (booster) dose of SARS-CoV-2 vaccination in nursing home residents have not been fully characterized. METHODS: This study included 117 individuals: 54 nursing home residents (mean age, 83.8 years; 39 SARS-CoV-2-naive and 15 previously infected) and 63 healthcare workers (mean age, 45.8 years; 32 SARS-CoV-2-naive and 31 previously infected). Anti-spike (receptor-binding domain [RBD]) and anti-nucleocapsid antibody responses to BNT162b2 mRNA vaccination and their related factors were evaluated using pre- (shortly and 6 months after the second dose) and post-booster vaccination samples. RESULTS: The median anti-spike (RBD) IgG level in SARS-CoV-2-naive residents 6 months after the second dose was the lowest among the four groups, with a decreasing rate of over 90%. The median rate of increase before and after the third dose in SARS-CoV-2-naive residents was significantly higher than that in SARS-CoV-2-naive healthcare workers (64.1- vs. 37.0-fold, P = 0.003), with the highest level among the groups. The IgG ratio of SARS-CoV-2-naive residents to healthcare workers after the second and third doses changed from one-fifth (20%) to one-half (50%). The rate of increase after the third dose in previously infected individuals was three- to fourfold, regardless of residents or healthcare workers. CONCLUSIONS: Advanced aged nursing home residents, poor responders in the initial SARS-CoV-2 vaccine series, could obtain sufficient antibody responses with the additional booster dose, despite more than 6 months after the second.

Clinical Significance of COVID-19 and Diabetes: In the Pandemic Situation of SARS-CoV-2 Variants including Omicron (B.1.1.529).

The coronavirus disease 2019 (COVID-19) global pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains uncontrolled, with the spread of emerging variants. According to accumulating evidence, diabetes is one of the leading risk factors for a severe COVID-19 clinical course, depending on the glycemic state before admission and during COVID-19 hospitalization. Multiple factors are thought to be responsible, including an altered immune response, coexisting comorbidity, and disruption of the renin-angiotensin system through the virus-host interaction. However, the precise underlying mechanisms remain under investigation. Alternatively, the focus is currently on the diabetogenic and ketosis-prone potential of SARS-CoV-2 itself, even for probable triggers of stress and steroid-induced hyperglycemia in COVID-19. In this article, we present a comprehensive review of the recent literature on the clinical and experimental findings associated with diabetes and COVID-19, and we discuss their bidirectional relationship, i.e., the risk for an adverse prognosis and the deleterious effects on glycometabolism. Accurate assessments of the incidence of new-onset diabetes induced by COVID-19 and its pathogenicity are still unknown, especially in the context of the circulation of SARS-CoV-2 variants, such as Omicron (B.1.1.529), which is a major challenge for the future.

SARS-CoV-2 spike L452R variant evades cellular immunity and increases infectivity.

Many SARS-CoV-2 variants with naturally acquired mutations have emerged. These mutations can affect viral properties such as infectivity and immune resistance. Although the sensitivity of naturally occurring SARS-CoV-2 variants to humoral immunity has been investigated, sensitivity to human leukocyte antigen (HLA)-restricted cellular immunity remains largely unexplored. Here, we demonstrate that two recently emerging mutations in the receptor-binding domain of the SARS-CoV-2 spike protein, L452R (in B.1.427/429 and B.1.617) and Y453F (in B.1.1.298), confer escape from HLA-A24-restricted cellular immunity. These mutations reinforce affinity toward the host entry receptor ACE2. Notably, the L452R mutation increases spike stability, viral infectivity, viral fusogenicity, and thereby promotes viral replication. These data suggest that HLA-restricted cellular immunity potentially affects the evolution of viral phenotypes and that a further threat of the SARS-CoV-2 pandemic is escape from cellular immunity.

Clinical significance of SARS-CoV-2-specific IgG detection with a rapid antibody kit for COVID-19 patients.

BACKGROUND: The longitudinal observation of the detection of antibody responses to SARS-CoV-2 using antibody kits during the clinical course of COVID-19 is not yet fully investigated. OBJECTIVES: To understand the significance of the detection of anti-SARS-CoV-2 antibodies, particularly IgG, using a rapid antibody kit, during the clinical course of COVID-19 patients with different severities. METHODS: Sixty-three serum samples from 18 patients (5 asymptomatic and 13 symptomatic patients) were retrospectively examined using a commercial SARS-CoV-2 IgM/IgG antibody kit. PCR positivity of patient samples was also examined as a marker of current SARS-CoV-2 infection. RESULTS: IgG antibodies were detected in all cases in this study. The IgG detection rates reached 100.0% in samples collected on day 13 or later. IgG seropositivity after an initial negative status was observed in 13 patients (3/5 asymptomatic and 10/13 symptomatic cases). Interestingly, the persistence of both PCR and IgG positivity was detected in seven cases, of which three were asymptomatic. The longest overlap duration of the PCR and IgG positivity was 17 days in asymptomatic status. CONCLUSIONS: SARS-CoV-2-specific IgG production can be detected in all infected individuals, using a rapid antibody kit, irrespective of clinical status. However, these findings suggest that, in some infected individuals, particularly those with asymptomatic status, the presence of virus-specific IgG antibodies does not imply prompt viral clearance.