Altered ISGylation drives aberrant macrophage-dependent immune responses during SARS-CoV-2 infection.

Ubiquitin-like protein ISG15 (interferon-stimulated gene 15) (ISG15) is a ubiquitin-like modifier induced during infections and involved in host defense mechanisms. Not surprisingly, many viruses encode deISGylating activities to antagonize its effect. Here we show that infection by Zika, SARS-CoV-2 and influenza viruses induce ISG15-modifying enzymes. While influenza and Zika viruses induce ISGylation, SARS-CoV-2 triggers deISGylation instead to generate free ISG15. The ratio of free versus conjugated ISG15 driven by the papain-like protease (PLpro) enzyme of SARS-CoV-2 correlates with macrophage polarization toward a pro-inflammatory phenotype and attenuated antigen presentation. In vitro characterization of purified wild-type and mutant PLpro revealed its strong deISGylating over deubiquitylating activity. Quantitative proteomic analyses of PLpro substrates and secretome from SARS-CoV-2-infected macrophages revealed several glycolytic enzymes previously implicated in the expression of inflammatory genes and pro-inflammatory cytokines, respectively. Collectively, our results indicate that altered free versus conjugated ISG15 dysregulates macrophage responses and probably contributes to the cytokine storms triggered by SARS-CoV-2.

Homologous and heterologous serological response to the N-terminal domain of SARS-CoV-2 in humans and mice.

The increasing numbers of infected cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses serious threats to public health and the global economy. Most SARS-CoV-2 neutralizing antibodies target the receptor binding domain (RBD) and some the N-terminal domain (NTD) of the spike protein, which is the major antigen of SARS-CoV-2. While the antibody response to RBD has been extensively characterized, the antigenicity and immunogenicity of the NTD protein are less well studied. Using 227 plasma samples from COVID-19 patients, we showed that SARS-CoV-2 NTD-specific antibodies could be induced during infection. As compared to the results of SARS-CoV-2 RBD, the serological response of SARS-CoV-2 NTD is less cross-reactive with SARS-CoV, a pandemic strain that was identified in 2003. Furthermore, neutralizing antibodies are rarely elicited in a mice model when NTD is used as an immunogen. We subsequently demonstrate that NTD has an altered antigenicity when expressed alone. Overall, our results suggest that while NTD offers a supplementary strategy for serology testing, it may not be suitable as an immunogen for vaccine development.

Neutralizing Antibody Response to Sarbecovirus Is Delayed in Sequential Heterologous Immunization.

Antigenic imprinting, which describes the bias of the antibody response due to previous immune history, can influence vaccine effectiveness. While this phenomenon has been reported for viruses such as influenza, there is little understanding of how prior immune history affects the antibody response to SARS-CoV-2. This study provides evidence for antigenic imprinting through immunization with two Sarbecoviruses, the subgenus that includes SARS-CoV-2. Mice were immunized subsequently with two antigenically distinct Sarbecovirus strains, namely SARS-CoV-1 and SARS-CoV-2. We found that sequential heterologous immunization induced cross-reactive binding antibodies for both viruses and delayed the emergence of neutralizing antibody responses against the booster strain. Our results provide fundamental knowledge about the immune response to Sarbecovirus and important insights into the development of pan-sarbecovirus vaccines and guiding therapeutic interventions.

Dynamics of B-cell repertoires and emergence of cross-reactive responses in COVID-19 patients with different disease severity.

COVID-19 patients show varying severity of the disease ranging from asymptomatic to requiring intensive care. Although a number of SARS-CoV-2 specific monoclonal antibodies have been identified, we still lack an understanding of the overall landscape of B-cell receptor (BCR) repertoires in COVID-19 patients. Here, we used high-throughput sequencing of bulk and plasma B-cells collected over multiple time points during infection to characterize signatures of B-cell response to SARS-CoV-2 in 19 patients. Using principled statistical approaches, we determined differential features of BCRs associated with different disease severity. We identified 38 significantly expanded clonal lineages shared among patients as candidates for specific responses to SARS-CoV-2. Using single-cell sequencing, we verified reactivity of BCRs shared among individuals to SARS-CoV-2 epitopes. Moreover, we identified natural emergence of a BCR with cross-reactivity to SARS-CoV-1 and SARS-CoV-2 in a number of patients. Our results provide important insights for development of rational therapies and vaccines against COVID-19.

Dynamics of B-cell repertoires and emergence of cross-reactive responses in COVID-19 patients with different disease severity.

COVID-19 patients show varying severity of the disease ranging from asymptomatic to requiring intensive care. Although a number of SARS-CoV-2 specific monoclonal antibodies have been identified, we still lack an understanding of the overall landscape of B-cell receptor (BCR) repertoires in COVID-19 patients. Here, we used high-throughput sequencing of bulk and plasma B-cells collected over multiple time points during infection to characterize signatures of B-cell response to SARS-CoV-2 in 19 patients. Using principled statistical approaches, we determined differential features of BCRs associated with different disease severity. We identified 38 significantly expanded clonal lineages shared among patients as candidates for specific responses to SARS-CoV-2. Using single-cell sequencing, we verified reactivity of BCRs shared among individuals to SARS-CoV-2 epitopes. Moreover, we identified natural emergence of a BCR with cross-reactivity to SARS-CoV-1 and SARS-CoV-2 in a number of patients. Our results provide important insights for development of rational therapies and vaccines against COVID-19.

Dynamics of B cell repertoires and emergence of cross-reactive responses in patients with different severities of COVID-19.

Individuals with the 2019 coronavirus disease (COVID-19) show varying severity of the disease, ranging from asymptomatic to requiring intensive care. Although monoclonal antibodies specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been identified, we still lack an understanding of the overall landscape of B cell receptor (BCR) repertoires in individuals with COVID-19. We use high-throughput sequencing of bulk and plasma B cells collected at multiple time points during infection to characterize signatures of the B cell response to SARS-CoV-2 in 19 individuals. Using principled statistical approaches, we associate differential features of BCRs with different disease severity. We identify 38 significantly expanded clonal lineages shared among individuals as candidates for responses specific to SARS-CoV-2. Using single-cell sequencing, we verify the reactivity of BCRs shared among individuals to SARS-CoV-2 epitopes. Moreover, we identify the natural emergence of a BCR with cross-reactivity to SARS-CoV-1 and SARS-CoV-2 in some individuals. Our results provide insights important for development of rational therapies and vaccines against COVID-19.

Cross-reactive Antibody Response between SARS-CoV-2 and SARS-CoV Infections.

The World Health Organization has declared the ongoing outbreak of COVID-19, which is caused by a novel coronavirus SARS-CoV-2, a pandemic. There is currently a lack of knowledge about the antibody response elicited from SARS-CoV-2 infection. One major immunological question concerns antigenic differences between SARS-CoV-2 and SARS-CoV. We address this question by analyzing plasma from patients infected by SARS-CoV-2 or SARS-CoV and from infected or immunized mice. Our results show that, although cross-reactivity in antibody binding to the spike protein is common, cross-neutralization of the live viruses may be rare, indicating the presence of a non-neutralizing antibody response to conserved epitopes in the spike. Whether such low or non-neutralizing antibody response leads to antibody-dependent disease enhancement needs to be addressed in the future. Overall, this study not only addresses a fundamental question regarding antigenicity differences between SARS-CoV-2 and SARS-CoV but also has implications for immunogen design and vaccine development.

Cross-reactive Antibody Response between SARS-CoV-2 and SARS-CoV Infections.

The World Health Organization has declared the ongoing outbreak of COVID-19, which is caused by a novel coronavirus SARS-CoV-2, a pandemic. There is currently a lack of knowledge about the antibody response elicited from SARS-CoV-2 infection. One major immunological question concerns antigenic differences between SARS-CoV-2 and SARS-CoV. We address this question by analyzing plasma from patients infected by SARS-CoV-2 or SARS-CoV and from infected or immunized mice. Our results show that, although cross-reactivity in antibody binding to the spike protein is common, cross-neutralization of the live viruses may be rare, indicating the presence of a non-neutralizing antibody response to conserved epitopes in the spike. Whether such low or non-neutralizing antibody response leads to antibody-dependent disease enhancement needs to be addressed in the future. Overall, this study not only addresses a fundamental question regarding antigenicity differences between SARS-CoV-2 and SARS-CoV but also has implications for immunogen design and vaccine development.

Cross-reactive antibody response between SARS-CoV-2 and SARS-CoV infections.

The World Health Organization has recently declared the ongoing outbreak of COVID-19, which is caused by a novel coronavirus SARS-CoV-2, as pandemic. There is currently a lack of knowledge in the antibody response elicited from SARS-CoV-2 infection. One major immunological question is concerning the antigenic differences between SARS-CoV-2 and SARS-CoV. We address this question by using plasma from patients infected by SARS-CoV-2 or SARS-CoV, and plasma obtained from infected or immunized mice. Our results show that while cross-reactivity in antibody binding to the spike protein is common, cross-neutralization of the live viruses is rare, indicating the presence of non-neutralizing antibody response to conserved epitopes in the spike. Whether these non-neutralizing antibody responses will lead to antibody-dependent disease enhancement needs to be addressed in the future. Overall, this study not only addresses a fundamental question regarding the antigenicity differences between SARS-CoV-2 and SARS-CoV, but also has important implications in vaccine.

Dilated common bile ducts mimicking choledochal cysts in ketamine abusers.

Substance abuse is a major health and social problem among Hong Kong youth and ketamine is the drug most commonly abused. Ketamine abuse is associated with a series of side-effects that include hallucination, nausea, vomiting, elevation of blood pressure, and urinary bladder dysfunction. Here we report three cases of ketamine abuse in which the abusers presented with recurrent epigastric pain and dilated common bile ducts that mimicked choledochal cysts on imaging. The dilated biliary tree may occur more frequently than was once assumed.

Preventing an Antigenically Disruptive Mutation in Egg-Based H3N2 Seasonal Influenza Vaccines by Mutational Incompatibility.

Egg-based seasonal influenza vaccines are the major preventive countermeasure against influenza virus. However, their effectiveness can be compromised when antigenic changes arise from egg-adaptive mutations on influenza hemagglutinin (HA). The L194P mutation is commonly observed in egg-based H3N2 vaccine seed strains and significantly alters HA antigenicity. An approach to prevent L194P would therefore be beneficial. We show that emergence of L194P during egg passaging can be impeded by preexistence of a G186V mutation, revealing strong incompatibility between these mutations. X-ray structures illustrate that individual G186V and L194P mutations have opposing effects on the HA receptor-binding site (RBS), and when both G186V and L194P are present, the RBS is severely disrupted. Importantly, wild-type HA antigenicity is maintained with G186V, but not L194P. Our results demonstrate that these epistatic interactions can be used to prevent the emergence of mutations that adversely alter antigenicity during egg adaptation.

Is regular follow-up scan for giant liver haemangioma necessary?

OBJECTIVES: To review the reliability of radiological diagnosis and need of regular scans for giant liver haemangioma, in terms of long-term outcome and management options. DESIGN: Retrospective study. SETTING: Division of Hepato-biliary and Pancreatic Surgery, Prince of Wales Hospital, Hong Kong. PATIENTS: Patients with giant liver haemangioma noted on initial imaging from February 1996 to July 2006. MAIN OUTCOME MEASURES: Patient demographics, clinical assessments, management, and outcomes. RESULTS: There were 42 female and 22 male patients with a median age of 49 (range, 27-84) years with a suspected haemangioma. The median maximal diameter of the lesions was 5.5 cm (range, 4.0-20.3 cm). They were first detected by ultrasonography (n=45), contrast-enhanced computed tomographic scan (n=18), or magnetic resonance imaging (n=1). Besides regular follow-up scans, 22 patients were investigated further to confirm the diagnosis/exclude malignancy. Finally, 63 patients had a haemangioma and one had a hepatocellular carcinoma. Regarding the patients with haemangiomas, two were operated on for relief of pain and the rest were managed conservatively. The median duration of follow-up was 34 months. Most (54%) of the patients were asymptomatic, but in 17% the haemangioma enlarged to exceed its original size by more than 20%. There were no haemangioma-associated complications. CONCLUSIONS: Majority of patients having giant liver haemangioma are asymptomatic and do not suffer complications. If the diagnosis is uncertain, selective further investigations may be necessary. Lesions with a confirmed diagnosis tend to remain static in size; performing regular scans for asymptomatic giant liver haemangiomas may not be necessary.

Laparoscopic versus open hepatectomy for liver tumours: a case control study.

OBJECTIVE: To evaluate the benefits of laparoscopic versus open resection of liver tumours. DESIGN: Case control study. SETTING: Tertiary teaching hospital, Hong Kong. PATIENTS: Data from 25 patients who underwent laparoscopic resections for liver tumours from 2003 to 2006 were compared to a retrospective series of 25 patients who underwent open hepatectomy in a pair-matched design. MAIN OUTCOME MEASURES: Duration of operation, operative morbidity and mortality, blood loss, tumour resection margin, analgesics usage, days to return to an oral diet, duration of postoperative hospital stay, and survival of patients with malignancy. RESULTS: The demographic data and the tumour characteristics were comparable in the two patient groups, as were mortality (0% in both groups) and morbidity rates (4% in both groups). Two (8%) of the patients having laparoscopic resections were converted to open surgery. There was no statistically significant difference between the two groups in terms of operating time or resection margins. However, the laparoscopically treated patients experienced significantly less blood loss (median, 100 vs 250 mL), had shorter hospital stays (median, 4 vs 7 days), were prescribed less analgesia (median morphine dosage, 0.16 vs 0.83 mg per kg body weight), and resumed oral diet earlier (median, 1 vs 2 days). For patients with malignant tumours, there was no significant difference between the two groups in terms of actuarial and disease-free survival. CONCLUSION: Compared to open hepatectomy, in selected patients laparoscopic liver resection delivers the benefits of decreased blood loss, shorter hospital stay, lesser requirement for analgesics, and an earlier return to an oral diet, without evidence of compromised oncological clearance.

Ruptured gastroduodenal artery pseudoaneurysm as the initial presentation of chronic pancreatitis.

Gastroduodenal artery pseudoaneurysm is a rare but life threatening complication of pancreatitis. Diagnosis and management of it remain challenging. Surgical treatment was associated with a high mortality. Percutaneous transarterial embolization of bleeding artery has recently been advocated as a definitive therapy and can be attempted as the initial measure to control bleeding. We herein report a case of chronic pancreatitis presented with ruptured pseudoaneurysm of gastroduodenal artery which was successfully controlled with transarterial embolisation.

Safe modification of the liver-hanging maneuver by endoscopic-assisted dissection of the retrohepatic tunnel.

As a safer approach to right hepatectomy, Belghiti et al. (J Am Coll Surg 193:109-11, 2001) described a liver-hanging maneuver. However, this procedure is performed blind, with the risks of damaging the small retrohepatic veins and consequential bleeding. To overcome this problem, we modified the procedure so that, instead of performing blind dissection using a long vascular clamp, we use a flexible choledochoscope to dissect the retrohepatic space filled by loose alveolar tissue anterior to the inferior vena cava (IVC). The avascular path is identified by a combination of saline irrigation and gentle movement of the tip of the choledochoscope. Cotton tape can then be passed around the liver parenchyma to elevate the liver away from the anterior surface of the IVC. This modification of Belghiti's liver-hanging maneuver allows direct vision along the plane anterior to the IVC, thus avoiding injury to the retrohepatic veins.

Axin utilizes distinct regions for competitive MEKK1 and MEKK4 binding and JNK activation.

Axin is a multidomain protein that plays a critical role in Wnt signaling, serving as a scaffold for down-regulation of beta-catenin. It also activates the JNK mitogen-activated protein kinase by binding to MEKK1. However, it is intriguing that Axin requires several additional elements for JNK activation, including a requirement for homodimerization, sumoylation at the extreme C-terminal sites, and a region in the protein phosphatase 2A-binding domain. In our present study, we have shown that another MEKK family member, MEKK4, also binds to Axin in vivo and mediates Axin-induced JNK activation. Surprisingly MEKK4 binds to a region distinct from the MEKK1-binding site. Dominant negative mutant of MEKK4 attenuates the JNK activation by Axin. Activation of JNK by Axin in MEKK1-/- mouse embryonic fibroblast cells supports the idea that another MEKK can mediate Axin-induced JNK activation. Expression of specific small interfering RNA against MEKK4 effectively attenuates JNK activation by the MEKK1 binding-defective Axin mutant in 293T cells and inhibits JNK activation by wild-type Axin in MEKK1-/- cells, confirming that MEKK4 is indeed another mitogen-activated protein kinase kinase kinase that is specifically involved in Axin-mediated JNK activation independently of MEKK1. We have also identified an additional domain between MEKK1- and MEKK4-binding sites as being required for JNK activation by Axin. MEKK1 and MEKK4 compete for Axin binding even though they bind to sites far apart, suggesting that Axin may selectively bind to MEKK1 or MEKK4 depending on distinct signals or cellular context. Our findings will provide new insights into how scaffold proteins mediate ultimate activation of different mitogen-activated protein kinase kinase kinases.