Impact of reinfection with SARS-CoV-2 Omicron variants in previously infected hamsters

The diversity of SARS-CoV-2 mutations raises the possibility of reinfection of individuals previously infected with earlier variants, and this risk is further increased by the emergence of the B.1.1.529 Omicron variant. In this study, we used an in vivo, hamster infection model to assess the potential for individuals previously infected with SARS-CoV-2 to be reinfected with Omicron variant and we also investigated the pathology associated with such infections. Initially, Syrian hamsters were inoculated with a lineage A, B.1.1.7, B.1.351, B.1.617.2 or a subvariant of Omicron, BA.1 strain and then reinfected with the BA.1 strain 5 weeks later. Subsequently, the impact of reinfection with Omicron subvariants (BA.1 and BA.2) in individuals previously infected with the BA.1 strain was examined. Although viral infection and replication were suppressed in both the upper and lower airways, following reinfection, virus-associated RNA was detected in the airways of most hamsters. Viral replication was more strongly suppressed in the lower respiratory tract than in the upper respiratory tract. Consistent amino acid substitutions were observed in the upper respiratory tract of infected hamsters after primary infection with variant BA.1, whereas diverse mutations appeared in hamsters reinfected with the same variant. Histopathology showed no acute pneumonia or disease enhancement in any of the reinfection groups and, in addition, the expression of inflammatory cytokines and chemokines in the airways of reinfected animals was only mildly elevated. These findings are important for understanding the risk of reinfection with new variants of SARS-CoV-2. IMPORTANCEThe emergence of SARS-CoV-2 variants and the widespread use of COVID-19 vaccines has resulted in individual differences in immune status against SARS-CoV-2. A decay in immunity over time and the emergence of variants that partially evade the immune response can also lead to reinfection. In this study, we demonstrated that, in hamsters, immunity acquired following primary infection with previous SARS-CoV-2 variants was effective in preventing the onset of pneumonia after reinfection with the Omicron variant. However, viral infection and multiplication in the upper respiratory tract were still observed after reinfection. We also showed that more diverse nonsynonymous mutations appeared in the upper respiratory tract of reinfected hamsters that had acquired immunity from primary infection. This hamster model reveals the within-host evolution of SARS-CoV-2 and its pathology after reinfection, and provides important information for countermeasures against diversifying SARS-CoV-2 variants.

SARS-CoV-2 ORF8 is a viral cytokine regulating immune responses

Many patients with severe COVID-19 suffer from pneumonia, and thus elucidation of the mechanisms underlying the development of such severe pneumonia is important. The ORF8 protein is a secreted protein of SARS-CoV-2, whose in vivo function is not well understood. Here, we analyzed the function of ORF8 protein by generating ORF8-knockout SARS-CoV-2. We found that the lung inflammation observed in wild-type SARS-CoV-2-infected hamsters was decreased in ORF8-knockout SARS-CoV-2-infected hamsters. Administration of recombinant ORF8 protein to hamsters also induced lymphocyte infiltration into the lungs. Similar pro-inflammatory cytokine production was observed in primary human monocytes treated with recombinant ORF8 protein. Furthermore, we demonstrate that the serum ORF8 protein levels are correlated well with clinical markers of inflammation. These results demonstrated that the ORF8 protein is a viral cytokine of SARS-CoV-2 involved in the in the immune dysregulation observed in COVID-19 patients, and that the ORF8 protein could be a novel therapeutic target in severe COVID-19 patients.

SARS-CoV-2 ORF6 disturbs nucleocytoplasmic trafficking to advance the viral replication

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the coronavirus disease 2019 pandemic. ORF6 is known to antagonize the interferon signaling by inhibiting the nuclear translocation of STAT1. Here we show that ORF6 acts as a virulence factor through two distinct strategies. First, ORF6 directly interacts with STAT1 in an IFN-independent manner to inhibit its nuclear translocation. Second, ORF6 directly binds to importin 1, which is a nuclear transport factor encoded by KPNA2, leading to a significant suppression of importin 1-mediated nuclear transport. Furthermore, we found that KPNA2 knockout enhances the viral replication, suggesting that importin 1 suppresses the viral propagation. Additionally, the analyses of gene expression data revealed that importin 1 levels decreased significantly in the lungs of older individuals. Taken together, SARS-CoV-2 ORF6 disrupts the nucleocytoplasmic trafficking to accelerate the viral replication, resulting in the disease progression, especially in older individuals.

High affinity modified ACE2 receptors prevent SARS-CoV-2 infection

The SARS-CoV-2 spike protein binds to the human angiotensin-converting enzyme 2 (ACE2) receptor via receptor binding domain (RBD) to enter into the cell and inhibiting this interaction is a main approach to inhibit SARS-CoV-2 infection. We engineered ACE2 to enhance the affinity with directed evolution in 293T cells. Three cycles of random mutation and cell sorting achieved 100-fold higher affinity to RBD than wild-type ACE2. The extracellular domain of modified ACE2 fused to the human IgG1-Fc region had stable structure and neutralized SARS-CoV-2 without the emergence of mutational escape. Therapeutic administration protected hamsters from SARS-CoV-2 infection, decreasing lung virus titers and pathology. Engineering ACE2 decoy receptors with human cell-based directed evolution is a promising approach to develop a SARS-CoV-2 neutralizing drug that has affinity comparable to monoclonal antibodies yet displaying resistance to escape mutations of virus. One Sentence SummaryEngineered ACE2 decoy receptor has a therapeutic potential against COVID-19 without viral escape mutation.

Generation of human bronchial organoids for SARS-CoV-2 research

Coronavirus disease 2019 (COVID-19) is a disease that causes fatal disorders including severe pneumonia. To develop a therapeutic drug for COVID-19, a model that can reproduce the viral life cycle and evaluate the drug efficacy of anti-viral drugs is essential. In this study, we established a method to generate human bronchial organoids (hBO) from commercially available cryopreserved human bronchial epithelial cells and examined whether they could be used as a model for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) research. Our hBO contain basal, club, ciliated, and goblet cells. Angiotensin-converting enzyme 2 (ACE2), which is a receptor for SARS-CoV-2, and transmembrane serine proteinase 2 (TMPRSS2), which is an essential serine protease for priming spike (S) protein of SARS-CoV-2, were highly expressed. After SARS-CoV-2 infection, not only the intracellular viral genome, but also progeny virus, cytotoxicity, pyknotic cells, and moderate increases of the type I interferon signal could be observed. Treatment with camostat, an inhibitor of TMPRSS2, reduced the viral copy number to 2% of the control group. Furthermore, the gene expression profile in SARS-CoV-2-infected hBO was obtained by performing RNA-seq analysis. In conclusion, we succeeded in generating hBO that can be used for SARS-CoV-2 research and COVID-19 drug discovery. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/115600v2_ufig1.gif" ALT="Figure 1"> View larger version (99K): org.highwire.dtl.DTLVardef@13a6908org.highwire.dtl.DTLVardef@1c59300org.highwire.dtl.DTLVardef@362167org.highwire.dtl.DTLVardef@1cb31ed_HPS_FORMAT_FIGEXP M_FIG C_FIG

Active Tuberculosis With Rapidly-Growing Pulmonary Lesion in a Hospitalized Dermatomyositis Patient Below Age 40 / 日本農村医学会雑誌

A 38-year-old man was admitted to our hospital with fever and skin rash, and he was diagnosed as having dermatomyositis. He was treated with anti-inflammatory steroid and immunosuppressive agents. On hospital day 48, chest computed tomography (CT) revealed a nodule measuring approximately 2 cm in size in the lower lobe of the right lung (S9). Bacterial and/or fungal infection was suspected, but there was no response to antibiotic or antifungal treatment. A week later, repeat chest CT revealed the tumor now measuring approximately 6 cm in size in the lower lobe of the right lung. We performed bronchoscopy, and bacteriological examination of the transbronchial biopsy specimen revealed pulmonary tuberculosis. Interferongamma release assay (IGRA) before the initiation of immunosuppressive treatment was negative, so we did not administer treatment for latent tuberculosis infection. He was, however, treated with isoniazid, rifampicin, ethambutol, and pyrazinamide for 9 months, following which radiological features improved gradually. Here we describe in detail this rare case of a negative IGRA result before immunosuppressive therapy in a relatively young Japanese man who went on to develop active tuberculosis with a rapidly-growing pulmonary lesion during hospitalization.

A Case of Amylase-producing Small Cell Lung Cancer Complicated by Cushing's Syndrome / 日本農村医学会雑誌

A 68-year-old man was admitted to our hospital with complaints of fatigue, polyuria, and loss of appetite, and was diagnosed with diabetic ketosis. Chest and abdominal computed tomography (CT) showed a pulmonary tumor on the right S3 and multiple liver tumors. Blood chemistry revealed elevated levels of amylase and hepatobiliary enzymes. Pathological examination of a biopsy specimen from the liver tumor showed a small cell carcinoma. Based on the imaging and pathological findings, we made a diagnosis of extensive disease small-cell lung cancer (ED-SCLC), cT1aN3M1b (HEP, ADR). Treatment with carboplatin and etoposide evoked partial response and the serum level of amylase decreased. Immunohistochemical staining of liver biopsy specimen was positive for amylase, leading to a diagnosis of SCLC with amylase production. About 22 months after the diagnosis of SCLC, he was admitted to our hospital with fatigue, muscular weakness, edema, and hyperpigmentation. Laboratory findings showed elevated serum levels of hepatobiliary enzymes, adrenocorticotropic hormone (ACTH), and cortisol, and a decreased serum potassium level. Urinary potassium level was elevated. Pituitary magnetic resonance imaging showed a normal morphology. We made a diagnosis of SCLC complicated by Cushing’s syndrome. We report this rare case of SCLC with amylase and ACTH production, which was detected in the course of treatment of SCLC.

Fabrication of Functional Cell Sheets with Human Thyrocytes from Non-Tumorous Thyroid Tissue

BACKGROUND: Engineered cell sheet transplantation has been considered an alternative physiological therapy for endocrine disorders. In this study, we attempted to fabricate functional human thyroid cell sheets using the engineering technology by culturing primary thyrocytes in free-feeder monolayers and assessed their proliferation and function in two different media. METHODS: The non-tumorous tissues (approximately 2 g) were dissected during surgery. Primary human thyroid cells were isolated by mechanical dispersion and treatment with isolation solution. The cells were cultured on tissue culture dishes or temperature-responsive culture dishes to induce the formation of detached cell sheets. RESULTS: Primary thyroid cells isolated from nine patients were positive for thyroid transcription factor 1, thyroglobulin (TG) and cytokeratin 7. Cell sheets with follicles were fabricated by cells incubated in both Dulbecco's Modified Eagle Medium (DMEM) and hepatocyte-defined medium (HDM) culture medium. The diameter and thickness of sheets fabricated in HDM were larger and thicker than those fabricated from DMEM. Furthermore, the cells incubated in HDM secreted higher levels of fT3 and fT4 than those incubated in DMEM. The thyroid peroxidase and TG mRNA of cells maintained in HDM were higher than those in cells maintained in DMEM. CONCLUSION: HDM appears suitable as a culture medium for maintaining primary thyrocytes and fabricating functional cell sheets. These in vitro findings may contribute to the development of appropriate culture conditions for human thyrocytes as well as engineered functional cell sheets.

Clinical Investigation of Patients with Lung Adenocarcinoma Harboring the EGFR T790M Mutation Diagnosed by Pleural or Pericardial Fluid Cell Block Methods / 日本農村医学会雑誌

In patients with epidermal growth factor receptor (EGFR) mutation-positive lung cancer (LC) who have acquired resistance to first and/or second-generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs), detection of EGFR T790M (T790M) mutation is essential before administration of osimertinib. Tissue sample is the main specimen used to detect the T790M mutation, and so cell block preparation using pleural or pericardial fluid should be considered. The utility of body cavity effusion cell block methods in T790M mutation detection have not yet been fully evaluated. This study aimed to evaluate the clinical background and treatment course of LC patients harboring the T790M mutation by using body cavity effusion cell block methods at our hospital. All patients were treated with first and/or second-generation EGFR-TKIs and had developed malignant pleural or pericardial fluid as a result of progressive disease. T790M mutation status was evaluated using body cavity effusion cell block method in 9 patients, from April 2016 to August 2017. We retrospectively evaluated the clinical characteristics and treatment course of these 9 patients (3 males and 6 females; median age 76 years). At the first diagnosis of LC, 7 patients had stage IV cancer; 4 patients were diagnosed by bronchial fibroscopy and 3 were diagnosed from pleural fluid examination. Regarding EGFR mutation, 3 and 6 patients carried the exon 19 deletion and L858R mutation, respectively. Median time interval between the first diagnosis of LC and T790M mutation evaluation was 30.8 months; 7 patients were diagnosed with positive T790M mutation by using body cavity effusion cell block methods. The T790M mutation was highly detected by examination of body cavity effusion cell blocks. Further evaluation is necessary with respect to variations in T790M detection rate based on the specimen collection site and/or progressive disease pattern in different patients.

A case of wild-type transthyretin amyloidosis associated with organizing pneumonia / Journal of Rural Medicine

<p>An 81-year-old man was referred to our hospital with bilateral multiple patchy opacities on chest radiography. His chief complaints were a few months’ history of intermittent mild cough and slightly yellow sputum. Chest computed tomography (CT) showed non-segmental air-space consolidations with ground-glass opacities. Amyloid deposition with organizing pneumonia (OP) was seen in transbronchial lung biopsy (TBLB) specimens from the left S8. Three months later, the infiltration originally seen in the left lower lobe was remarkably diminished, and new infiltrations in the lingual and right lower lobes were detected on chest CT. Amyloid deposition with OP was seen in TBLB specimens from the left S4. Transthyretin was detected following immunohistochemical examination. The presence of wild-type transthyretin (ATTRwt) was proven using genetic analysis. The present report describes a rare case of ATTRwt amyloidosis associated with OP.</p>

A Case of Primary Racemose Hemangioma Discovered from Abnormal Chest X-ray Finding / 日本農村医学会雑誌

　　A 56-year-old woman was referred to our hospital because of an abnormal finding in the right pulmonary hilum on chest X-ray. Enhanced chest computed tomography showed hyperplastic bronchial arteries dilating and winding around the trachea and bronchi. A racemose hemangioma of the bronchial artery with multiple bronchial artery aneurysms (diameter <20mm) was seen displacing the trachea and both main bronchi. Bronchoscopy showed submucosal tumor-like lesions at the distal trachea and in both main bronchi, and a dusky-red elevated pulsatile lesion at the orifice of the left B3b＋c. We performed coil embolization of the bronchial artery aneurysm to prevent abrupt rupture of the bronchial aneurysm.