Project description:Mink, on a farm with about 15,000 animals, became infected with SARS-CoV-2. Over 75% of tested animals were positive for SARS-CoV-2 RNA in throat swabs and 100% of tested animals were seropositive. The virus responsible had a deletion of nucleotides encoding residues H69 and V70 within the spike protein gene as well as the A22920T mutation, resulting in the Y453F substitution within this protein, seen previously in mink. The infected mink recovered and after free-testing of 300 mink (a level giving 93% confidence of detecting a 1% prevalence), the animals remained seropositive. During further follow-up studies, after a period of more than 2 months without any virus detection, over 75% of tested animals again scored positive for SARS-CoV-2 RNA. Whole genome sequencing showed that the viruses circulating during this re-infection were most closely related to those identified in the first outbreak on this farm but additional sequence changes had occurred. Animals had much higher levels of anti-SARS-CoV-2 antibodies in serum samples after the second round of infection than at free-testing or during recovery from initial infection, consistent with a boosted immune response. Thus, it was concluded that following recovery from an initial infection, seropositive mink were readily re-infected by SARS-CoV-2.
Project description:Dysregulated immune responses contribute to the excessive and uncontrolled inflammation observed in severe COVID-19. However, how immunity to SARS-CoV-2 is induced and regulated remains unclear. Here we uncover a role of the complement system in the induction of innate and adaptive immunity to SARS-CoV-2. Complement rapidly opsonizes SARS-CoV-2 particles via the lectin pathway. Complement-opsonized SARS-CoV-2 efficiently induces type-I interferon and pro-inflammatory cytokine responses via activation of dendritic cells, which are inhibited by antibodies against the complement receptors (CR) 3 and 4. Serum from COVID-19 patients, or monoclonal antibodies against SARS-CoV-2, attenuate innate and adaptive immunity induced by complement-opsonized SARS-CoV-2. Blocking of CD32, the FcγRII antibody receptor of dendritic cells, restores complement-induced immunity. These results suggest that opsonization of SARS-CoV-2 by complement is involved in the induction of innate and adaptive immunity to SARS-CoV-2 in the acute phase of infection. Subsequent antibody responses limit inflammation and restore immune homeostasis. These findings suggest that dysregulation of the complement system and FcγRII signaling may contribute to severe COVID-19.
Project description:To explore the relationship between SARS-CoV-2 infection in different time before operation and postoperative main complications (mortality, main pulmonary and cardiovascular complications) 30 days after operation; To determine the best timing of surgery after SARS-CoV-2 infection.
Project description:HAE cultures were infected with SARS-CoV, SARS-dORF6 or SARS-BatSRBD and were directly compared to A/CA/04/2009 H1N1 influenza-infected cultures. Cell samples were collected at various hours post-infection for analysis. Time Points = 0, 12, 24, 36, 48, 60, 72, 84 and 96 hrs post-infection for SARS-CoV, SARS-dORF6 and SARS-BatSRBD. Time Points = 0, 6, 12, 18, 24, 36 and 48 hrs post-infection for H1N1. Done in triplicate or quadruplicate for RNA Triplicates/quadruplicates are defined as 3/4 different wells, plated at the same time and using the same cell stock for all replicates. Time matched mocks done in triplicate from same cell stock as rest of samples. Culture medium (the same as what the virus stock is in) will be used for the mock infections. Infection was done at an MOI of 2.
Project description:HAE cultures were infected with SARS-CoV, SARS-ddORF6 or SARS-BatSRBD and were directly compared to A/CA/04/2009 H1N1 influenza-infected cultures. Cell samples were collected at various hours post-infection for analysis. Time Points = 0, 12, 24, 36, 48, 60, 72, 84 and 96 hrs post-infection for SARS-CoV. Time Points = 0, 24, 48, 60, 72, 84 and 96 hrs post-infection forSARS-ddORF6 and SARS-BatSRBD. Time Points = 0, 6, 12, 18, 24, 36 and 48 hrs post-infection for H1N1. Done in triplicate/quadruplicate for RNA Triplicates/quadruplicates are defined as 3/4 different wells, plated at the same time and using the same cell stock for all replicates. Time matched mocks done in triplicate from same cell stock as rest of samples. Culture medium (the same as what the virus stock is in) will be used for the mock infections. Infection was done at an MOI of 2.
Project description:HAE cultures were infected with SARS-CoV, SARS-dORF6 or SARS-BatSRBD and were directly compared to A/CA/04/2009 H1N1 influenza-infected cultures. Cell samples were collected at various hours post-infection for analysis. Time Points = 0, 12, 24, 36, 48, 60, 72, 84 and 96 hrs post-infection for SARS-CoV, SARS-dORF6 and SARS-BatSRBD. Time Points = 0, 6, 12, 18, 24, 36 and 48 hrs post-infection for H1N1. Done in triplicate for RNA Triplicates are defined as 3 different wells, plated at the same time and using the same cell stock for all replicates. Time matched mocks done in triplicate from same cell stock as rest of samples. Culture medium (the same as what the virus stock is in) will be used for the mock infections. Infection was done at an MOI of 2 for SARS viruses and an MOI of 1 for H1N1.
Project description:Immunocompromised patients who have a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection pose many clinical and public health challenges. We describe the case of a hematopoietic stem cell transplantation patient with lymphoma who had a protracted illness requiring three consecutive hospital admissions. Whole genome sequencing confirmed two different SARS-CoV-2 clades. Clinical management issues and the unanswered questions arising from this case are discussed.
Project description:Interferon-induced transmembrane proteins (IFITMs) restrict infections by many viruses, but a subset of IFITMs enhance infections by specific coronaviruses through currently unknown mechanisms. We show that SARS-CoV-2 Spike-pseudotyped virus and genuine SARS-CoV-2 infections are generally restricted by human and mouse IFITM1, IFITM2, and IFITM3, using gain- and loss-of-function approaches. Mechanistically, SARS-CoV-2 restriction occurred independently of IFITM3 S-palmitoylation, indicating a restrictive capacity distinct from reported inhibition of other viruses. In contrast, the IFITM3 amphipathic helix and its amphipathic properties were required for virus restriction. Mutation of residues within the IFITM3 endocytosis-promoting Yxx? motif converted human IFITM3 into an enhancer of SARS-CoV-2 infection, and cell-to-cell fusion assays confirmed the ability of endocytic mutants to enhance Spike-mediated fusion with the plasma membrane. Overexpression of TMPRSS2, which increases plasma membrane fusion versus endosome fusion of SARS-CoV-2, attenuated IFITM3 restriction and converted amphipathic helix mutants into infection enhancers. In sum, we uncover new pro- and anti-viral mechanisms of IFITM3, with clear distinctions drawn between enhancement of viral infection at the plasma membrane and amphipathicity-based mechanisms used for endosomal SARS-CoV-2 restriction.
Project description:The current investigation was conducted with the objective to develop an epidemiological case definition of possible severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) re-infection and assess its magnitude in India. The epidemiological case definition for SARS-CoV-2 re-infection was developed from literature review of data on viral kinetics. For achieving second objective, the individuals who satisfied the developed case definition for SARS-CoV-2 re-infection were contacted telephonically. Taking available evidence into consideration, re-infection with SARS-CoV-2 in our study was defined as any individual who tested positive for SARS-CoV-2 on two separate occasions by either molecular tests or rapid antigen test at an interval of at least 102 days with one negative molecular test in between. In this archive based, telephonic survey, 58 out of 1300 individuals (4.5%) fulfilled the above-mentioned definition; 38 individuals could be contacted with healthcare workers (HCWs) accounting for 31.6% of the cases. A large proportion of participants was asymptomatic and had higher Ct value during the first episode. While SARS-CoV-2 re-infection is still a rare phenomenon, there is a need for epidemiological definition of re-infection for establishing surveillance systems and this study contributes to such a goal.Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) re-infection is an emerging concern and there is a need to define it. Therefore, working epidemiological case definition for re-infection was developed and its magnitude was explored via archive-based, telephonic survey. Re-infection with SARS-CoV-2 was defined as two positive tests at an interval of at least 102 days with one interim negative test. Thirty-eight of the 58 eligible patients could be contacted with 12 (31.6%) being HCWs. Majority of the participants were asymptomatic and had higher Ct value during their first episode. To conclude, a working epidemiological case definition of SARS-CoV-2 re-infection is important to strengthen surveillance. The present investigation contributes to this goal and records reinfection in 4.5% of SARS-CoV-2 infected individuals in India.
Project description:BackgroundUnderstanding the level and characteristics of protection from past SARS-CoV-2 infection against subsequent re-infection, symptomatic COVID-19 disease, and severe disease is essential for predicting future potential disease burden, for designing policies that restrict travel or access to venues where there is a high risk of transmission, and for informing choices about when to receive vaccine doses. We aimed to systematically synthesise studies to estimate protection from past infection by variant, and where data allow, by time since infection.MethodsIn this systematic review and meta-analysis, we identified, reviewed, and extracted from the scientific literature retrospective and prospective cohort studies and test-negative case-control studies published from inception up to Sept 31, 2022, that estimated the reduction in risk of COVID-19 among individuals with a past SARS-CoV-2 infection in comparison to those without a previous infection. We meta-analysed the effectiveness of past infection by outcome (infection, symptomatic disease, and severe disease), variant, and time since infection. We ran a Bayesian meta-regression to estimate the pooled estimates of protection. Risk-of-bias assessment was evaluated using the National Institutes of Health quality-assessment tools. The systematic review was PRISMA compliant and was registered with PROSPERO (number CRD42022303850).FindingsWe identified a total of 65 studies from 19 different countries. Our meta-analyses showed that protection from past infection and any symptomatic disease was high for ancestral, alpha, beta, and delta variants, but was substantially lower for the omicron BA.1 variant. Pooled effectiveness against re-infection by the omicron BA.1 variant was 45·3% (95% uncertainty interval [UI] 17·3-76·1) and 44·0% (26·5-65·0) against omicron BA.1 symptomatic disease. Mean pooled effectiveness was greater than 78% against severe disease (hospitalisation and death) for all variants, including omicron BA.1. Protection from re-infection from ancestral, alpha, and delta variants declined over time but remained at 78·6% (49·8-93·6) at 40 weeks. Protection against re-infection by the omicron BA.1 variant declined more rapidly and was estimated at 36·1% (24·4-51·3) at 40 weeks. On the other hand, protection against severe disease remained high for all variants, with 90·2% (69·7-97·5) for ancestral, alpha, and delta variants, and 88·9% (84·7-90·9) for omicron BA.1 at 40 weeks.InterpretationProtection from past infection against re-infection from pre-omicron variants was very high and remained high even after 40 weeks. Protection was substantially lower for the omicron BA.1 variant and declined more rapidly over time than protection against previous variants. Protection from severe disease was high for all variants. The immunity conferred by past infection should be weighed alongside protection from vaccination when assessing future disease burden from COVID-19, providing guidance on when individuals should be vaccinated, and designing policies that mandate vaccination for workers or restrict access, on the basis of immune status, to settings where the risk of transmission is high, such as travel and high-occupancy indoor settings.FundingBill & Melinda Gates Foundation, J Stanton, T Gillespie, and J and E Nordstrom.