Specific long-term changes in anti-SARS-CoV-2 IgG modifications and antibody functions in mRNA, adenovector, and protein subunit vaccines.

Various vaccine platforms were developed and deployed against the COVID-19 disease. The Fc-mediated functions of IgG antibodies are essential in the adaptive immune response elicited by vaccines. However, the long-term changes of protein subunit vaccines and their combinations with mRNA vaccines are unknown. A total of 272 serum and plasma samples were collected from individuals who received first to third doses of the protein subunit Medigen, the mRNA (BNT), or the adenovector AstraZeneca vaccines. The IgG subclass level was measured using enzyme-linked immunosorbent assay, and Fc-N glycosylation was measured using LC-MS/MS. Antibody-dependent phagocytosis (ADCP) and complement deposition (ADCD) of anti-spike (S) IgG antibodies were measured. IgG1 and 3 reached the highest anti-S IgG subclass level. IgG1, 2, and 4 subclass levels significantly increased in mRNA- and Medigen-vaccinated individuals. Fc-glycosylation was stable, except in female BNT vaccinees, who showed increased bisection and decreased galactosylation. Female BNT vaccinees had a higher anti-S IgG titer than that of males. ADCP declined in all groups. ADCD increased in Medigen-vaccinated individuals after the third dose. Each vaccine produced specific long-term changes in Fc structure and function. This finding is critical when selecting a vaccine platform or combination to achieve the desired immune response.

Reflecting on the 1998 enterovirus outbreak: A 25-year retrospective and learned lessons.

Enterovirus A71 (EV-A71) infections pose a significant public health concern in the Asia-Pacific region. EV-A71 is primarily responsible for causing hand, foot, and mouth disease (HFMD) in children. However, this virus can also lead to severe and potentially fatal neurological consequences in affected individuals. This review aims to provide a comprehensive understanding of the molecular virology, epidemiology, and recombination events associated with EV-A71. The literature extensively covers the clinical manifestations and neurological symptoms that accompany EV-A71 infections. One of the complications explored in this review is brainstem encephalitis, which can arise as a result of EV-A71 infections. Brainstem encephalitis refers to inflammation of the brainstem, a critical region responsible for various bodily functions. The review examines the underlying mechanisms, diagnostic criteria, treatment options, and prognosis for central nervous system infections involving EV-A71. Neurological complications associated with EV-A71 infections are diverse and can have severe consequences. These complications may include aseptic meningitis, acute flaccid paralysis, and acute transverse myelitis. The review delves into the pathophysiology of these complications, shedding light on the molecular mechanisms through which EV-A71 affects the central nervous system. Accurate diagnosis of EV-A71 infections is crucial for appropriate management and treatment. Treatment options for EV-A71 infections primarily focus on supportive care, as there are currently no specific antiviral drugs available for this virus. The review highlights the importance of managing symptoms, such as fever, dehydration, and pain relief, to alleviate the burden on affected individuals. Prognosis for individuals with central nervous system (CNS) infections involving EV-A71 can vary depending on the severity of the complications. The review provides insights into the long-term outcomes and potential neurological sequelae associated with EV-A71 infections. In conclusion, EV-A71 infections have emerged as a major public health concern in the Asia-Pacific region. This review aims to enhance our understanding of the molecular virology, epidemiology, and neurological complications associated with EV-A71. By examining the underlying mechanisms, diagnostic criteria, treatment options, and prognosis, this review contributes to the development of effective strategies for the prevention, diagnosis, and management of EV-A71 infections. The paper presents a comprehensive analysis of worldwide data pertaining to outbreaks of EV-A71 and HFMD. The subsequent discourse delves into the advancement and strategic formulation pertaining to the creation of vaccines targeting EV-A71. In summary, this study provides a comprehensive examination of the potential obstacles and considerations involved in the management and treatment of EV-A71 infections. Additionally, it proposes suggestions for future research and development endeavors with the objective of formulating efficacious treatment approaches for this viral infection.

Non-neutralizing functions in anti-SARS-CoV-2 IgG antibodies.

Most individuals infected with or vaccinated against COVID-19 develop antigenic neutralizing immunoglobulin G (IgG) antibodies against the SARS-CoV-2 spike protein. Although neutralizing antibodies are biomarkers of the adaptive immune response, their mere presence is insufficient to explain the protection afforded against the disease or its pathology. IgG exhibits other secondary effector functions that activate innate immune components, including complement, natural killer cells, and macrophages. The affinity for effector cells depends on the isotypes and glycosylation of IgG antibodies. The anti-spike IgG titer should be sufficient to provide significant Fc-mediated effects in severe COVID-19, mRNA, and protein subunit vaccinations. In combination with aberrant effector cells, pro-inflammatory afucosylated IgG1 and IgG3 may be detrimental in severe COVID-19. The antibody response of mRNA vaccines leads to higher fucosylation and a less inflammatory IgG profile, with a long-term shift to IgG4, which is correlated with protection from disease.

Impact of patient characteristics on innate immune responses and inflammasome activation in ex vivo human lung tissues infected with influenza A virus.

Background: Influenza A virus (IAV) infection poses a persistent global health challenge, necessitating a nuanced grasp of host immune responses for optimal interventions. While the interplay between aging, immunosenescence, and IAV is recognized as key in severe lower respiratory tract infections, the role of specific patient attributes in shaping innate immune reactions and inflammasome activity during IAV infection remains under-investigated. In this study, we utilized an ex vivo infection model of human lung tissues with H3N2 IAV to discern relationships among patient demographics, IAV nucleoprotein (NP) expression, toll-like receptor (TLR) profiles, PD-1/PD-L1 markers, and cytokine production. Methods: Our cohort consisted of thirty adult patients who underwent video-assisted thoracoscopic surgery during 2018-2019. Post-surgical lung tissues were exposed to H3N2 IAV for ex vivo infections, and the ensuing immune responses were profiled using flow cytometry. Results: We observed pronounced IAV activity within lung cells, as indicated by marked NP upregulation in both epithelial cells (P = 0.022) and macrophages (P = 0.003) in the IAV-exposed group relative to controls. Notably, interleukin-2 levels correlated with variations in TLR1 expression on epithelial cells and PD-L1 markers on macrophages. Age emerged as a modulating factor, dampening innate immune reactions, as evidenced by reduced interleukin-2 and interferon-γ concentrations (both adjusted P < 0.05). Intriguingly, a subset of participants with pronounced tumor necrosis factor-alpha post-mock infection (Cluster 1) showed attenuated cytokine responses in contrast to their counterparts in Cluster 2 and Cluster 3 (all adjusted P < 0.05). Individuals in Cluster 2, characterized by a low post-mock infection NP expression in macrophages, exhibited reduced variations in both NP and TLR1-3 expressions on these cells and a decreased variation in interleukin-2 secretion in comparison to their Cluster 3 counterparts, who were identified by their elevated NP macrophage expression (all adjusted P < 0.05). Conclusion: Our work elucidates the multifaceted interplay of patient factors, innate immunity, and inflammasome responses in lung tissues subjected to ex vivo H3N2 IAV exposure, reflecting real-world lower respiratory tract infections. While these findings provide a foundation for tailored therapeutic strategies, supplementary studies are requisite for thorough validation and refinement.

Emergence and Persistent Dominance of SARS-CoV-2 Omicron BA.2.3.7 Variant, Taiwan.

Since April 2022, waves of SARS-CoV-2 Omicron variant cases have surfaced in Taiwan and spread throughout the island. Using high-throughput sequencing of the SARS-CoV-2 genome, we analyzed 2,405 PCR-positive swab samples from 2,339 persons and identified the Omicron BA.2.3.7 variant as a major lineage within recent community outbreaks in Taiwan.

Targeting influenza A virus by splicing inhibitor herboxidiene reveals the importance of subtype-specific signatures around splice sites.

BACKGROUND: The association between M segment splicing and pathogenicity remains ambiguous in human influenza A viruses. In this study, we aimed to investigate M splicing in various human influenza A viruses and characterize its physiological roles by applying the splicing inhibitor, herboxidiene. METHODS: We examined the M splicing of human H1N1 and H3N2 viruses by comparing three H1N1 and H3N2 strains, respectively, through reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. We randomly selected M sequences of human H1N1, H2N2, and H3N2 viruses isolated from 1933 to 2020 and examined their phylogenetic relationships. Next, we determined the effects of single nucleotide variations on M splicing by generating mutant viruses harboring the 55C/T variant through reverse genetics. To confirm the importance of M2 splicing in the replication of H1N1 and H3N2, we treated infected cells with splicing inhibitor herboxidiene and analyzed the viral growth using plaque assay. To explore the physiological role of the various levels of M2 protein in pathogenicity, we challenged C57BL/6 mice with the H1N1 WSN wild-type strain, mutant H1N1 (55T), and chimeric viruses including H1N1 + H3wt and H1N1 + H3mut. One-tailed paired t-test was used for virus titer calculation and multiple comparisons between groups were performed using two-way analysis of variance. RESULTS: M sequence splice site analysis revealed an evolutionarily conserved single nucleotide variant C55T in H3N2, which impaired M2 expression and was accompanied by collinear M1 and mRNA3 production. Aberrant M2 splicing resulted from splice-site selection rather than a general defect in the splicing process. The C55T substitution significantly reduced both M2 mRNA and protein levels regardless of the virus subtype. Consequently, herboxidiene treatment dramatically decreased both the H1N1 and H3N2 virus titers. However, a lower M2 expression only attenuated H1N1 virus replication and in vivo pathogenicity. This attenuated phenotype was restored by M replacement of H3N2 M in a chimeric H1N1 virus, despite low M2 levels. CONCLUSIONS: The discrepancy in M2-dependence emphasizes the importance of M2 in human influenza A virus pathogenicity, which leads to subtype-specific evolution. Our findings provide insights into virus adaptation processes in humans and highlights splicing regulation as a potential antiviral target.

The 5'UTR of HCoV-OC43 adopts a topologically constrained structure to intrinsically repress translation.

The emergence of SARS-CoV-2, which is responsible for the COVID-19 pandemic, has highlighted the need for rapid characterization of viral mechanisms associated with cellular pathogenesis. Viral UTRs represent conserved genomic elements that contribute to such mechanisms. Structural details of most CoV UTRs are not available, however. Experimental approaches are needed to allow for the facile generation of high-quality viral RNA tertiary structural models, which can facilitate comparative mechanistic efforts. By integrating experimental and computational techniques, we herein report the efficient characterization of conserved RNA structures within the 5'UTR of the HCoV-OC43 genome, a lab-tractable model coronavirus. We provide evidence that the 5'UTR folds into a structure with well-defined stem-loops (SLs) as determined by chemical probing and direct detection of hydrogen bonds by NMR. We combine experimental base-pair restraints with global structural information from SAXS to generate a 3D model that reveals that SL1-4 adopts a topologically constrained structure wherein SLs 3 and 4 coaxially stack. Coaxial stacking is mediated by short linker nucleotides and allows SLs 1 to 2 to sample different cojoint orientations by pivoting about the SL3,4 helical axis. To evaluate the functional relevance of the SL3,4 coaxial helix, we engineered luciferase reporter constructs harboring the HCoV-OC43 5'UTR with mutations designed to abrogate coaxial stacking. Our results reveal that the SL3,4 helix intrinsically represses translation efficiency since the destabilizing mutations correlate with increased luciferase expression relative to wildtype without affecting reporter mRNA levels, thus highlighting how the 5'UTR structure contributes to the viral mechanism.

The internal ribosome entry site determines the neurotropic potential of enterovirus A71.

The mechanisms underlying tissue-specific replication of enteroviruses are currently unclear. Although enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are both common pathogens that cause hand-foot-mouth disease, they display quite different neurotropic properties. Herein, we characterized the role of the internal ribosome entry site (IRES) in determining neurovirulence using an oral inoculation model of EV-A71. The receptor transgenic (hSCARB2-Tg) mice developed neurological symptoms after being infected with a mouse-adapted EV-A71 strain (MP4) via different administrative routes. Intragastric administration of the MP4 strain caused pathological changes such as neuronal loss and neuropil vacuolation, whereas replacing EV-A71 IRES with CV-A16 abolished the neuropathological phenotypes. The attenuated neurotropic potential of IRES-swapped EV-A71 was observed even in mice that received intraperitoneal and intracerebral inoculations. Fewer chimeric MP4 viral RNAs and proteins were detected in the mouse tissues, regardless of the inoculation route. Tissue-specific replication can be reflected in cell-based characterization. While chimeric MP4 virus replicated poorly in human intestinal C2BBe1 and neuroblastoma SH-SY5Y cells, its replication in susceptible rhabdomyosarcoma cells was not affected. Overall, our results demonstrated that the IRES determined the neurotropic potential of EV-A71 and CV-A16, emphasizing the importance of the IRES in tissue tropism, along with the host receptors.

Effect of hot water extracts of Arthrospira maxima (spirulina) against respiratory syncytial virus.

BACKGROUND: Spirulina (Arthrospira maxima) hot water extracts such as calcium spirulan (Ca-SP) have demonstrated antiviral effects against herpes simplex virus (HSV), human immunodeficiency virus-1 (HIV-1), and influenza virus infections. There is no prior evidence suggesting the anti-viral activity of the spirulina hot water extract against respiratory syncytial virus (RSV). PURPOSE: There are currently no effective antivirals available to treat RSV infection. Therefore, the development of safe and novel anti-RSV drugs is urgent and necessary. The aim of this work was to demonstrate the anti-RSV activity of spirulina hot water extracts and determine the potential mechanism of action. METHODS: Cytotoxicity and anti-RSV activity of spirulina hot water extracts were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutralization assays, respectively. Potential mechanisms and components were assessed using time of addition, attachment, internalization, pull-down assays, and composition analysis. RESULTS: The polysaccharide-enriched high-molecular weight fraction (>100 kDa, SHD1) had a high total sugar content, with rhamnose accounting for approximately 60 mol% of total monosaccharides. The main glycosyl linkages included 3-, 4-, and 2,3-rhamnopyranosyl linkages. All spirulina hot water extracts showed no toxicity toward human epithelial type 2 (HEp-2) cells but demonstrated anti-RSV activity. The SHD1 had a half maximal effective concentration (EC50) of 0.0915 mg/ml and a selective index (SI) of >261.5 against RSV. SHD1 significantly reduced viral yield in a dose-dependent manner during the RSV attachment stage. SHD1 disrupted RSV internalization and inhibited RSV attachment (G) protein binding to heparan sulfate receptors on the host cell surface, thus preventing RSV attachment and entry. CONCLUSION: SHD1 serves as an effective candidate for novel drug development against RSV infection.

Factors influencing neutralizing antibody titers elicited by coronavirus disease 2019 vaccines.

The World Health Organization has highlighted the importance of an international standard (IS) for severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) neutralizing antibody titer detection to calibrate diagnostic techniques. We applied an IS to calibrate neutralizing antibody titers (NTs) (international units/mL) in response to coronavirus disease 2019 (COVID-19) vaccination. Moreover, the association between different factors and neutralizing antibodies was analyzed. A total of 1667 serum samples were collected from participants receiving different COVID-19 vaccines. Antibody titers were determined by a microneutralization assay using live viruses in a biosafety level 3 (BSL-3) laboratory and a commercial serological MeDiPro kit. The titer determined using the MeDiPro kit was highly correlated with the NT determined using live viruses and calibrated using IS. Fever and antipyretic analgesic treatment were related to neutralizing antibody responses in ChAdOx1-S and BNT162b2 vaccinations. Individuals with diabetes showed a low NT elicited by MVC-COV1901. Individuals with hypertension receiving the BNT162b2 vaccine had lower NTs than those without hypertension. Our study provided the international unit (IU) values of NTs in vaccinated individuals for the development of vaccines and implementation of non-inferiority trials. Correlation of the influencing factors with NTs can provide an indicator for selecting COVID-19 vaccines based on personal attributes.

Titers and breadth of neutralizing antibodies against SARS-CoV-2 variants after heterologous booster vaccination in health care workers primed with two doses of ChAdOx1 nCov-19: A single-blinded, randomized clinical trial.

OBJECTIVES: We conducted a single-blinded, randomized trial to evaluate the safety, reactogenicity, and immunogenicity of heterologous booster vaccination in health care workers (HCW) who had received two doses of ChAdOx1 nCov-19. METHODS: HCW who had at least 90 days after the second dose were enrolled to receive one of the four vaccines: BNT162b2 (30 µg), half-dose mRNA-1273 (50 µg), mRNA-1273 (100 µg), and MVC-COV1901 (15 µg). The primary outcomes were humoral and cellular immunogenicity and secondary outcomes assessed safety and reactogenicity at 28 days post-booster. RESULTS: MVC-COV1901 Three hundred and forty HCW were enrolled: 83 received BNT162b2 (2 excluded), 85 half-dose mRNA-1273, 85 mRNA-1273, and 85 MVC-COV1901. mRNA vaccines had more reactogenicity than protein vaccine. The fold-rise of anti-spike IgG geometric mean titer was 8.4 (95% CI 6.8-10.4) for MVC-COV1901, 32.2 (27.2-38.1) for BNT162b2, 47.6 (40.8-55.6) for half-dose mRNA-1273 and 63.2 (53.6-74.6) for mRNA-1273. The live virus microneutralization assays (LVMNA) against the wild type, alpha and delta variants were consistent with anti-spike IgG for all booster vaccines. The LVMNA in the four groups against omicron BA.1 variant were 6.4 to 13.5 times lower than those against the wild type. All booster vaccines induced a comparable T cell response. CONCLUSIONS: Third dose booster not only increases neutralizing antibody titer but also enhances antibody breadth against SARS-CoV-2 variants. mRNA vaccines are preferred booster vaccines for those who received primary series of ChAdOx1 nCov-19.

The Bottlenecks of Preparing Virus Particles by Size Exclusion for Antibody Generation.

Enterovirus 71 (EV71) is the major etiological agent contributing to the development of hand-foot-mouth disease (HFMD). There are not any global available vaccines or antibody drugs against EV71 released yet. In this study, we perform the virus immunization in a cost-effective and convenient approach by preparing virus particles from size exclusion and immunization of chicken. Polyclonal yolk-immunoglobulin (IgY) was simply purified from egg yolk and monoclonal single-chain variable fragments (scFv) were selected via phage display technology with two scFv libraries containing 6.0 × 106 and 1.3 × 107 transformants. Specific clones were enriched after 5 rounds of bio-panning and four identical genes were classified after the sequence analysis. Moreover, the higher mutation rates were revealed in the CDR regions, especially in the CDR3. IgY showed specific binding activities to both EV71-infected and Coxsackievirus 16-infected cell lysates and high infectivity inhibitory activity of EV71. However, while IgY detected a 37 kDa protein, the selected scFv seemingly detected higher size proteins which could be cell protein instead of EV71 proteins. Despite the highly effective chicken antibody generation, the purity of virus particles prepared by size exclusion is the limitation of this study, and further characterization should be carried out rigorously.

A randomized controlled trial of heterologous ChAdOx1 nCoV-19 and recombinant subunit vaccine MVC-COV1901 against COVID-19.

Heterologous prime-boost COVID-19 vaccine strategy may facilitate mass COVID-19 immunization. We reported early immunogenicity and safety outcomes of heterologous immunization with a viral vector vaccine (ChAdOx1) and a spike-2P subunit vaccine (MVC-COV1901) in a participant-blinded, randomized, non-inferiority trial (NCT05054621). A total of 100 healthy adults aged 20-70 years having the first dose of ChAdOx1 were 1:1 randomly assigned to receive a booster dose either with ChAdOx1 (n = 50) or MVC-COV1901 (n = 50) at an interval of 4-6 or 8-10 weeks. At day 28 post-boosting, the neutralizing antibody geometric mean titer against wild-type SARS-CoV-2 in MVC-COV1901 recipients (236 IU/mL) was superior to that in ChAdOx1 recipients (115 IU/mL), with a GMT ratio of 2.1 (95% CI, 1.4 to 2.9). Superiority in the neutralizing antibody titer against Delta variant was also found for heterologous MVC-COV1901 immunization with a GMT ratio of 2.6 (95% CI, 1.8 to 3.8). Both spike-specific antibody-secreting B and T cell responses were substantially enhanced by the heterologous schedule. Heterologous boosting was particularly prominent at a short prime-boost interval. No serious adverse events occurred across all groups. The findings support the use of heterologous prime-boost with ChAdOx1 and protein-based subunit vaccines.

Microwave resonant absorption of SARS-CoV-2 viruses.

Low power microwave can effectively deactivate influenza type A virus through the nonthermal structure-resonant energy transfer effect, at a frequency matching the confined-acoustic dipolar mode frequency of the virus. Currently, aerosol is considered the major route for SARS-CoV-2 transmission. For the potential microwave-based sterilization, the microwave-resonant frequency of SARS-CoV-2 must be unraveled. Here we report a microwave absorption spectroscopy study of the SARS-CoV-2 and HCoV-229E viruses through devising a coplanar-waveguide-based sensor. Noticeable microwave absorption can be observed, while we identified the resonant frequencies of the 1st and 2nd dipolar modes of SARS-CoV-2 virus as 4 and 7.5 GHz respectively. We further found that the resonant frequencies are invariant to the virus titer, and we also studied the microwave absorption of HCoV-229E in weak acidity medium to simulate the common pH value in fluid secretion. Our results suggest the possible radiation frequency for the recently proposed microwave sterilization devices to inactivate SARS-CoV-2 virus through a nonthermal mechanism so as to control the disease transmission in the post-pandemic era.

Visualizing Influenza A Virus vRNA Replication.

Influenza A virus (IAV) has caused recurrent epidemics and severe pandemics. In this study, we adapted an MS2-MCP live-cell imaging system to visualize IAV replication. A reporter plasmid, pHH-PB2-vMSL, was constructed by replacing a part of the PB2-coding sequence in pHH-PB2 with a sequence encoding 24 copies of a stem-loop structure from bacteriophage MS2 (MSL). Binding of MS2 coat protein (MCP) fused to green fluorescent protein (GFP) to MSL enabled the detection of vRNA as fluorescent punctate signals in live-cell imaging. The introduction of pHH-PB2-vMSL into A549 cells transduced to express an MCP-GFP fusion protein lacking the nuclear localization signal (MCP-GFPdN), subsequently allowed tracking of the distribution and replication of PB2-vMSL vRNA after IAV PR8 infection. Spatial and temporal measurements revealed exponential increases in vRNA punctate signal intensity, which was only observed after membrane blebbing in apoptotic cells. Similar signal intensity increases in apoptotic cells were also observed after MDCK cells, transduced to express MCP-GFPdN, were infected with IAV carrying PB2-vMSL vRNA. Notably, PB2-vMSL vRNA replication was observed to occur only in apoptotic cells, at a consistent time after apoptosis initiation. There was a lack of observable PB2-vMSL vRNA replication in non-apoptotic cells, and vRNA replication was suppressed in the presence of apoptosis inhibitors. These findings point to an important role for apoptosis in IAV vRNA replication. The utility of the MS2-imaging system for visualizing time-sensitive processes such as viral replication in live host cells is also demonstrated in this study.

Adequacy of Hemodialysis Serves as an Independent Predictor of Humoral Response to ChAdOx1 Prime-Boost Vaccination in Hemodialysis Patients.

Background: Immune response assessed by the quantification of neutralizing antibodies (nAbs) and predictors associated with immunogenicity after the prime-boost ChAdOx1 (Oxford−AstraZeneca) COVID-19 vaccine in hemodialysis (HD) patients remains unclear. Methods: This prospective study enrolled 174 HD patients and 67 healthy subjects to evaluate antibodies against the spike protein 1 and receptor-binding domain of severe acute respiratory syndrome coronavirus type 2 after prime-booster vaccination, by using enzyme-linked immunosorbent assay and applied spline-based generalized additive model regression analysis to predict 50% neutralization titer (NT50). The correlation between HD parameters and NT50 was analyzed. Results: NT50 was lower in HD patients compared with healthy controls after the prime-boost dose (p < 0.001). The geometric mean titer ratios were higher in first-dose seronegative than in the seropositive subgroup in HD patients and healthy controls (6.96 vs. 2.36, p = 0.002, and 9.28 vs. 1.26, p = 0.011, respectively). After two doses of ChAdOx1, one-way ANOVA showed that Ca × P was positively associated with NT50 (p trend = 0.043) and multiple linear regression showed the similar results (p = 0.021). Kt/V (a quantification of dialysis adequacy) (OR = 20.295, p = 0.005) could independently predict seroconversion (NT50 ≥ 35.13 IU/mL). Conclusion: Adequacy of hemodialysis could independently predict seroconversion in HD subjects vaccinated with prime-boost doses of ChAdOx1.

Anti-Spike Antibody Response to Natural Infection with SARS-CoV-2 and Its Activity against Emerging Variants.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has substantially affected human health globally. Spike-specific antibody response plays a major role in protection against SARS-CoV-2 infection. Here, we examined serological anti-spike antibody and memory B cell responses in adults with acute SARS-CoV-2 infection. Twenty-five adult patients were enrolled between January and September 2020, and 21 (84%) had a detectable spike-binding antibody response in serum on day 21 ± 8 (6 to 33) after the onset of illness. Among those with positive spike-binding antibody response, 19 (90%) had a positive hemagglutination titer and 15 (71%) had angiotensin-converting enzyme 2 (ACE2)-blocking serological activities. Follow-up serum samples collected 11 ± 1 (7 to 15) months after infection exhibited an average of 2.6 ± 1.0 (1.0 to 3.5)-fold reduction in the spike-binding antibody response. Moreover, convalescent and follow-up serum samples showed 83 ± 82 (15 to 306)- and 165 ± 167 (12 to 456)-fold reductions in the neutralization activity against the Omicron variant, respectively. Upon acute infection, spike-specific memory B cell responses were elicited, with an average frequency of 1.3% ± 1.2% of peripheral B cells on day 19 ± 7 (6 to 33) after the onset of illness. IgM memory B cells were predominantly induced. Patients with fever and pneumonia showed significantly stronger spike-binding, ACE2-blocking antibody, and memory B cell responses. In conclusion, spike-specific antibody response elicited upon acute SARS-CoV-2 infection may wane over time and be compromised by the emergence of viral variants. IMPORTANCE As spike protein-specific antibody responses play a major role in protection against SARS-CoV-2, we examined spike-binding and ACE2-blocking antibody responses in SARS-CoV-2 infection at different time points. We found robust responses following acute infection, which waned approximately 11 months after infection. Patients with fever and pneumonia showed significantly stronger spike-binding, ACE2-blocking antibody, and memory B cell responses. In particular, spike-specific antibody response in the convalescent and follow-up serum samples was substantially affected by emerging variants, especially Beta and Omicron variants. These results warrant continued surveillance of spike-specific antibody responses to natural infections and highlight the importance of maintaining functional anti-spike antibodies through immunization.

Durability and Immunogenicity of Neutralizing Antibodies Response Against Omicron Variants After Three Doses of Subunit SARS-CoV-2 Vaccine MVC-COV1901: An Extension to an Open-Label, Dose-Escalation Phase 1 Study.

INTRODUCTION: MVC-COV1901 is a protein subunit COVID-19 vaccine based on the stable prefusion spike protein S-2P adjuvanted with CpG 1018 and aluminum hydroxide. Interim results of a phase 2 clinical trial demonstrated favorable safety profile and immunogenicity and the vaccine has been authorized for use in Taiwan. However, waning antibody levels after immunization and variants of concern (VoC) could negatively impact vaccine-induced neutralization of virus. In this extension to the phase 1 clinical study we investigated a three-dose regimen of MVC-COV1901 for durability of antibody levels and virus neutralization capacity, including neutralization of the Omicron variant. METHODS: Forty-five healthy adults from 20 to 49 years of age were divided into three groups of 15 participants receiving two doses of either low dose (LD), medium dose (MD), or high dose (HD) of MVC-COV1901. Six months after the second dose (day 209), a third MD dose of MVC-COV1901 was administered to the LD and MD groups and a HD dose was given to the HD group. Safety was followed for up to 28 days after the booster dose by monitoring incidences of adverse events (AE). Immunogenicity and antibody persistence for up to 6 months after the booster dose were assessed by neutralizing assay with the wild-type (Wuhan) SARS-CoV-2 virus. To examine the immunogenicity of booster dose against variants, neutralizing assays were carried out with the Alpha, Beta, and Delta variant viruses and the Omicron variant pseudovirus using samples from 4 weeks after the booster dose. RESULTS: Adverse reactions after the booster dose were mostly mild and comparable to that of the first two doses. Compared to day 209, neutralizing antibodies were increased by 10.3-28.9 times at 4 weeks after the booster. During the 6-month follow-up after the booster, the rate of decline of neutralizing antibody level was much less than that after the second dose. Three doses of MVC-COV1901 also improved antibody-mediated neutralization of Alpha, Beta, and Delta variants as well as the Omicron variant pseudovirus. CONCLUSION: Our data showed increased persistence of neutralizing antibodies and enhancement of immunogenicity against VoCs offered after a third dose of MVC-COV1901. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04487210.

Evolution and Epidemiology of SARS-CoV-2 Virus.

A novel coronavirus (CoV) that emerged in Wuhan, Hubei province in China, in December 2019, has rapidly spread worldwide. Named as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), this virus has been responsible for infecting about 153 million people and causing 3 million deaths by May 2021. There is obvious interest in gaining novel insights into the epidemiologic evolution of this virus; however, inappropriate application and interpretation of genomic and phylogenetic analyses has led to dangerous outcomes and misunderstandings. This chapter focuses on not only introducing this virus, its genomic characteristics and molecular mechanisms but also describing the application and interpretation of phylogenetic tree analyses, in order to provide useful information to better understand the evolution and epidemiology of this virus. In addition, recombinant region and genetic ancestry of SARS-CoV-2 remain unknown. It is urgently required to collect samples and obtain related viral genetic data from animal sources for identifying the intermediate host of SARS-CoV-2 that is responsible for its cross-species transmission.

Efficacy, safety, and immunogenicity of an inactivated, adjuvanted enterovirus 71 vaccine in infants and children: a multiregion, double-blind, randomised, placebo-controlled, phase 3 trial.

BACKGROUND: Children are susceptible to severe or fatal enterovirus 71 (EV71) infections. We aimed to evaluate the efficacy, safety, and immunogenicity of EV71vac, an aluminium phosphate-adjuvanted inactivated EV71 vaccine in children aged 2-71 months. METHODS: We did a randomised, double-blinded, placebo-controlled, phase 3 trial at five hospitals in Taiwan and two in Vietnam. Children aged 2-71 months were stratified by country and age, and randomly assigned (1:1) to receive two doses of EV71vac or placebo via intramuscular injection 56 days apart. Children aged 2-23 months received a third booster dose on day 366. The primary endpoint was the clinical efficacy of the total vaccinated cohort against EV71-associated diseases during the follow-up period, from 14 days after the second dose to when 15 cases of EV71 infections were confirmed in the per-protocol population. Our safety analysis included all participants who received at least one dose of EV71vac. This trial is registered with ClinicalTrials.gov, NCT03865238, and is complete. FINDINGS: Between April 23 and Dec 25, 2019, of 3663 children assessed, 3061 were randomly assigned, of whom 3049 were vaccinated: 1521 children in the EV71vac group and 1528 in the placebo group. By May 20, 2021, our primary efficacy analysis included 2959 children, with 1476 children in the EV71vac group and 1483 children in the placebo group. The vaccine efficacy of EV71vac was 96·8% (95% CI 85·5-100) against EV71 associated diseases (p<0·0001). The percentage of participants who reported solicited adverse events were similar in both groups: 865 (56·9%) in the EV71vac group and 852 (55·8%) in the placebo group. Almost all reported solicited adverse events were mild and self-limited. INTERPRETATION: EV71vac is safe, well-tolerated, and highly effective in preventing EV71 associated diseases in children aged 2-71 months. FUNDING: Medigen Vaccine Biologics and A+ Industrial Innovative R&D Program of the Ministry of Economic Affairs, Taiwan.