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1.
Methods ; 201: 26-33, 2022 05.
Article in English | MEDLINE | ID: covidwho-1915093

ABSTRACT

In recent years, the usage of digital polymerase chain reaction (dPCR) for various clinical applications has increased exponentially. In this study, a dPCR assay optimized on the Clarity Plus™ dPCR system was evaluated for the absolute quantification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the global coronavirus disease 2019 (COVID-19) outbreak. The assay demonstrated good inter- and intra- assay precision, accuracy, as well as excellent linearity across a range of over 6 orders of magnitude for target gene quantification. In addition, a comparison of the assay on both dPCR and qPCR platforms revealed that dPCR exhibited a slightly higher sensitivity compared to its qPCR counterpart when quantifying SARS-CoV-2 at a lower concentration. Overall, the results showed that the dPCR assay is a reliable and effective approach for the absolute quantification of SARS-CoV-2 and can be a valuable molecular tool in clinical applications such as detecting low viral loads in patients as well as in wastewater surveillance of COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , RNA, Viral/analysis , RNA, Viral/genetics , Real-Time Polymerase Chain Reaction , SARS-CoV-2/genetics , Waste Water/analysis , Wastewater-Based Epidemiological Monitoring
2.
Adv Healthc Mater ; 11(14): e2200283, 2022 07.
Article in English | MEDLINE | ID: covidwho-1843840

ABSTRACT

The eye is susceptible to viral infections, causing severe ocular symptoms or even respiratory diseases. Methods capable of protecting the eye from external viral invasion in a long-term and highly effective way are urgently needed but have been proved to be extremely challenging. Here, a strategy of forming a long-acting protective ocular surface is described by instilling adhesive dual-antiviral nanoparticles. Taking pseudotyped severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a model virus, antiviral agent-loaded nanoparticles are coated with a "double-lock" hybrid cell membrane abundant with integrin-ß1 and angiotensin converting enzyme II (ACE2). After instillation, the presence of integrin-ß1 endows coated nanoparticles with steady adhesion via specific binding to Arg-Gly-Asp sequence on the fibronectin of ocular epithelium, achieving durable retention on the ocular surface. In addition to loaded inhibitors, the exposure of ACE2 can trap SARS-CoV-2 and subsequently neutralize the associated spike protein, playing a dual antiviral effect of the resulting nanoparticles. Adhesive dual-antiviral nanoparticles enabled by coating with a "double-lock" hybrid cell membrane could be a versatile platform for topical long-acting protection against viral infection of the eye.


Subject(s)
Antiviral Agents , COVID-19 , Eye Diseases , Eye , Nanoparticles , Adhesives/pharmacology , Angiotensin-Converting Enzyme 2 , Antiviral Agents/pharmacology , COVID-19/drug therapy , Eye/drug effects , Eye/virology , Eye Diseases/prevention & control , Eye Diseases/virology , Humans , Integrins , SARS-CoV-2
3.
Nano Today ; 40: 101280, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1386357

ABSTRACT

New vaccine technologies are urgently needed to produce safe and effective vaccines in a more timely manner to prevent future infectious disease pandemics. Here, we describe erythrocyte-mediated systemic antiviral immunization, a versatile vaccination strategy that boosts antiviral immune responses by using erythrocytes decorated with virus-mimetic nanoparticles carrying a viral antigen and a Toll-like receptor (TLR) agonist. As a proof of concept, polydopamine nanoparticles were synthesized via a simple in situ polymerization in which the nanoparticles were conjugated with the SARS-CoV-2 spike protein S1 subunit and the TLR7/8 agonist R848. The resulting SARS-CoV-2 virus-mimetic nanoparticles were attached to erythrocytes via catechol groups on the nanoparticle. Erythrocytes naturally home to the spleen and interact with the immune system. Injection of the nanoparticle-decorated erythrocytes into mice resulted in greater maturation and activation of antigen-presenting cells, humoral and cellular immune responses in the spleen, production of S1-specific immunoglobulin G (IgG) antibodies, and systemic antiviral T cell responses than a control group treated with the nanoparticles alone, with no significant negative side effects. These results show that erythrocyte-mediated systemic antiviral immunization using viral antigen- and TLR agonist-presenting polydopamine nanoparticles-a generalizable method applicable to many viral infections-is effective new approach to developing vaccines against severe infectious diseases.

4.
Lancet Infect Dis ; 21(5): 617-628, 2021 05.
Article in English | MEDLINE | ID: covidwho-1033382

ABSTRACT

BACKGROUND: Wuhan was the first epicentre of COVID-19 in the world, accounting for 80% of cases in China during the first wave. We aimed to assess household transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and risk factors associated with infectivity and susceptibility to infection in Wuhan. METHODS: This retrospective cohort study included the households of all laboratory-confirmed or clinically confirmed COVID-19 cases and laboratory-confirmed asymptomatic SARS-CoV-2 infections identified by the Wuhan Center for Disease Control and Prevention between Dec 2, 2019, and April 18, 2020. We defined households as groups of family members and close relatives who did not necessarily live at the same address and considered households that shared common contacts as epidemiologically linked. We used a statistical transmission model to estimate household secondary attack rates and to quantify risk factors associated with infectivity and susceptibility to infection, accounting for individual-level exposure history. We assessed how intervention policies affected the household reproductive number, defined as the mean number of household contacts a case can infect. FINDINGS: 27 101 households with 29 578 primary cases and 57 581 household contacts were identified. The secondary attack rate estimated with the transmission model was 15·6% (95% CI 15·2-16·0), assuming a mean incubation period of 5 days and a maximum infectious period of 22 days. Individuals aged 60 years or older were at a higher risk of infection with SARS-CoV-2 than all other age groups. Infants aged 0-1 years were significantly more likely to be infected than children aged 2-5 years (odds ratio [OR] 2·20, 95% CI 1·40-3·44) and children aged 6-12 years (1·53, 1·01-2·34). Given the same exposure time, children and adolescents younger than 20 years of age were more likely to infect others than were adults aged 60 years or older (1·58, 1·28-1·95). Asymptomatic individuals were much less likely to infect others than were symptomatic cases (0·21, 0·14-0·31). Symptomatic cases were more likely to infect others before symptom onset than after (1·42, 1·30-1·55). After mass isolation of cases, quarantine of household contacts, and restriction of movement policies were implemented, household reproductive numbers declined by 52% among primary cases (from 0·25 [95% CI 0·24-0·26] to 0·12 [0·10-0·13]) and by 63% among secondary cases (from 0·17 [0·16-0·18] to 0·063 [0·057-0·070]). INTERPRETATION: Within households, children and adolescents were less susceptible to SARS-CoV-2 infection but were more infectious than older individuals. Presymptomatic cases were more infectious and individuals with asymptomatic infection less infectious than symptomatic cases. These findings have implications for devising interventions for blocking household transmission of SARS-CoV-2, such as timely vaccination of eligible children once resources become available. FUNDING: National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities, US National Institutes of Health, and US National Science Foundation.


Subject(s)
COVID-19/transmission , SARS-CoV-2 , Adolescent , Adult , Age Factors , Aged , COVID-19/etiology , Child , Child, Preschool , China/epidemiology , Disease Susceptibility , Family Characteristics , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Retrospective Studies , Risk Factors , Young Adult
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