Optimization of Anti-SARS-CoV-2 Treatments Based on Curcumin, Used Alone or Employed as a Photosensitizer.

Curcumin, the bioactive compound of the spice Curcuma longa, has already been reported as a potential COVID-19 adjuvant treatment due to its immunomodulatory and anti-inflammatory properties. In this study, SARS-CoV-2 was challenged with curcumin; moreover, curcumin was also coupled with laser light at 445 nm in a photodynamic therapy approach. Curcumin at a concentration of 10 µM, delivered to the virus prior to inoculation on cell culture, inhibited SARS-CoV-2 replication (reduction >99%) in Vero E6 cells, possibly due to disruption of the virion structure, as observed using the RNase protection assay. However, curcumin was not effective as a prophylactic treatment on already-infected Vero E6 cells. Notably, when curcumin was employed as a photosensitizer and blue laser light at 445 nm was delivered to a mix of curcumin/virus prior to the inoculation on the cells, virus inactivation was observed (>99%) using doses of curcumin that were not antiviral by themselves. Photodynamic therapy employing crude curcumin can be suggested as an antiviral option against SARS-CoV-2 infection.

Surfactin Bacterial Antiviral Lipopeptide Blocks In Vitro Replication of SARS-CoV-2

Despite great efforts have been made worldwide, the coronavirus disease 19 (COVID-19) still has not a definitive cure, although the availability of different vaccines are slowing down the transmission and severity. It has been shown that surfactin, a cyclic lipopeptide produced by Bacillus subtilis, is a molecule able to counteract both SARS-CoV-1, MERS-CoV and HCoV-229E coronaviruses. In this study the potential antiviral activity of surfactin against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was tested in vitro in a cellular model of infection. Our results show that 2 h treatment with surfactin is able to reduce SARS-CoV-2 infectivity on Vero E6 cells both at 24 h and after 7 days from viral inoculation, probably impairing the viral membrane integrity. Moreover, surfactin, at the concentrations used in our experimental settings, is not cytotoxic. We suggest surfactin as a new potential molecule against SARS-CoV-2, to be employed at least as a disinfectant.

Adamantiades-Behçet disease: from clinical heterogeneity to diagnosis during the COVID-19 pandemic.

Adamantiades-Behçet disease (ABD) is a systemic disease with vasculitis, characterized by recurrent oral aphthosis and ocular, cutaneous, articular, vascular, cardiopulmonary manifestations and it is mainly found in the territories of the antique "silk road". ABD pathogenesis remains unknown although genetic, infectious and environmental factors seem to be implicated in the development of the disease, which is considered an auto-inflammatory condition. COVID-19 infection can present some symptoms, in particular at the level of oral and pulmonary mucosa, which require a differential diagnosis with ABD. Furthermore, the immunological alterations of this disease, and the drugs used for its treatment could influence the infection by COVID-19, and its clinical evolution. Nevertheless, vaccination anti-COVID-19 is recommended in ABD patients. The most commonly used diagnostic criteria for ABD are those established in 2014 by the International Team for the Revision of the International Criteria for BD (ITR-ICBD). Furthermore, criteria for disease severity according to the Overall Damage Index of Behçet's Syndrome (BODI) have recently been proposed in order to quantify the severity of the disease as well as the evolution during follow-up. In ABD patients it is mandatory to investigate on the presence of active/latent tuberculosis, because of the common organ involvement, such as eyes and bowel. ABD has a high morbidity and low mortality, sometimes linked to the rupture of an arterial aneurysm and/or neurological complications. This article is based on a general review on ABD ranging from the history of ABD to possible causes and clinical manifestations. A specific section has been dedicated to the COVID-19 pandemic.

Comparison between nucleic acid amplification tests, antigen immunofluorescence assay, and in vitro infectivity in SARS-CoV-2 diagnosis.

The number of SARS-CoV-2 detection tests requested to the laboratories has dramatically increased together with an urgent need to release reliable responses in a very short time. The two options taken into consideration and analyzed in the current study were the point-of-care test (POCT) based on the nucleic acid amplification test (NAAT) and the Antigen (Ag) rapid test. The POCT-NAAT-based assay was compared with a rapid antigen test of nasopharyngeal swab samples. If the specimen tested positive, it was followed by viral load quantification and by the functional assessment of the residual infectivity. When the initial cycle threshold (Ct) was below 20 (100%), and in the range of 20-25 (92%) and of 25-30 (88%), a great concordance between the POCT-NAAT and the Ag test was observed. Moreover, the positivity of the antigen test was well correlated to a successful infection in vitro (78%), with greater concordance when the initial Ct below 20 or above 35 (100%) and in the range 20-25 (83%). Our findings showed that most of the swabs which tested positive using the antigen test were able to infect the cells in vitro, suggesting that probably only these samples hold residual infectivity and therefore an increased risk of virus transmission at the moment of being tested.

Effect of Short Time of SARS-CoV-2 Infection in Caco-2 Cells.

Coronavirus disease 19 (COVID-19) clinical manifestations include the involvement of the gastrointestinal tract, affecting around 10% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children. In the present work, the consequence of a short time of viral absorption (5, 15, 30 and 60 min) was tested on the Caco-2 intestinal epithelial cell line. Our findings show that Caco-2 cells are highly permissive to SARS-CoV-2 infection, even after 5 min of viral inoculation at a multiplicity of infection of 0.1. No cytopathic effect was evident during the subsequent 7 days of monitoring; nevertheless, the immunofluorescence staining for the viral nucleocapsid confirmed the presence of intracellular SARS-CoV-2. Our findings highlight the very short time during which SARS-CoV-2 is able to infect these cells in vitro.

Effect of Short Time of SARS-CoV-2 Infection in Caco-2 Cells

Coronavirus disease 19 (COVID-19) clinical manifestations include the involvement of the gastrointestinal tract, affecting around 10% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected children. In the present work, the consequence of a short time of viral absorption (5, 15, 30 and 60 min) was tested on the Caco-2 intestinal epithelial cell line. Our findings show that Caco-2 cells are highly permissive to SARS-CoV-2 infection, even after 5 min of viral inoculation at a multiplicity of infection of 0.1. No cytopathic effect was evident during the subsequent 7 days of monitoring;nevertheless, the immunofluorescence staining for the viral nucleocapsid confirmed the presence of intracellular SARS-CoV-2. Our findings highlight the very short time during which SARS-CoV-2 is able to infect these cells in vitro.

SARS-CoV-2 RNA Recovery from Air Sampled on Quartz Fiber Filters: A Matter of Sample Preservation?

The airborne route of transmission of SARS-CoV-2 was confirmed by the World Health Organization in April 2021. There is an urge to establish standardized protocols for assessing the concentration of SARS-CoV-2 RNA in air samples to support risk assessment, especially in indoor environments. Debates on the airborne transmission route of SARS-CoV-2 have been complicated because, among the studies testing the presence of the virus in the air, the percentage of positive samples has often been very low. In the present study, we report preliminary results on a study for the evaluation of parameters that can influence SARS-CoV-2 RNA recovery from quartz fiber filters spotted either by standard single-stranded SARS-CoV-2 RNA or by inactivated SARS-CoV-2 virions. The analytes were spiked on filters and underwent an active or passive sampling;then, they were preserved at −80 °C for different numbers of days (0 to 54) before extraction and analysis. We found a mean recovery of 2.43%, except for the sample not preserved (0 days) that showed a recovery of 13.51%. We found a relationship between the number of days and the recovery percentage. The results presented show a possible issue that relates to the quartz matrix and SARS-CoV-2 RNA recovery. The results are in accordance with the already published studies that described similar methods for SARS-CoV-2 RNA field sampling and that reported non-detectable concentrations of RNA. These outcomes could be false negatives due to sample preservation conditions. Thus, until further investigation, we suggest, as possible alternatives, to keep the filters: (i) in a sealed container for preservation at 4 °C;and (ii) in a viral transport medium for preservation at a temperature below 0 °C.

Direct inactivation of SARS-CoV-2 by low level blue photobiomodulation LED at 470, 454 and 450 nm.

Blue light has been already reported as able to counteract different types of microorganisms including Gram-positive and Gram-negative bacteria, fungi and viruses, especially the enveloped ones. It has been reported that both blue and visible light can efficiently impact SARS-CoV-2 by affecting its ability to replicate in in vitro cellular models of infection. In this study, blue light at 450, 454 and 470 nm was tested on SARS-CoV-2 to evaluate the residual viral infectious potential on Vero E6, Caco-2 and Calu-3 cells, after the irradiation of viral particles. Following 12' of irradiation at 40 mW/cm2 , a drastic block of viral amplification was observed. Indeed, at 7 days post-irradiation/infection the viral load was the same as the one measured 1 day post-irradiation/infection, and cellular viability was maintained showing similar levels to the noninfected control cells. Taken together our results indicate that blue LED lamps can be considered as a cheap and convenient tool for SARS-CoV-2 disinfection.

Low sensitivity of rapid tests detecting anti-CoV-2 IgG and IgM in health care workers' serum for COVID-19 screening.

BACKGROUND: the sensitivity and specificity of a rapid antibody test were investigated for the screening of healthcare workers. METHODS: the serum of 389 health care workers exposed to COVID-19 patients or with symptoms, were analysed. All workers underwent monthly the screening for SARS-CoV-2 with detection of viral RNA in nasopharyngeal swabs by RT-PCR. IgG antibody detection in serum was performed by Chemiluminescence Immunoassay (CLIA) and by the Rapid test (KHB diagnostic kit for SARS CoV-2 IgM/IgG antibody after a median of 7.6 weeks (25°-75° percentiles 6.6-11.5). RESULTS: the rapid test resulted positive in 31/132 (23.5%), 16/135 (11.8%) and 0/122 cases in COVID-19 positive individuals, in those with only SARS-CoV-2 IgG antibodies and in those negative for both tests, respectively. Sensitivity was 17.6% (CI95% 13.2-22.7) and 23.5% (CI95% 16.5-31.6), and specificity was 100% (CI95% 97-100) and 100% (CI95% 97-100) considering Rapid test vs CLIA IgG or Rapid test vs SARS-CoV-2 positive RNA detection, respectively. CONCLUSION: the KHB Rapid test is not suitable for the screening of workers with previous COVID-19 infection.

Evaluation of Residual Infectivity after SARS-CoV-2 Aerosol Transmission in a Controlled Laboratory Setting.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is mainly transmitted through respiratory droplets, aerosols, or direct contact with fomites from an infected subject. It has been reported that SARS-CoV-2 is stable and viable in aerosol up to 16 h in controlled laboratory conditions. However, the aerosolization conditions varied a lot between the studies. In this work, an experimental laboratory model of SARS-CoV-2 aerosolization was established, employing an impinger nebulizer, a cylindrical chamber for aerosol travel, and a SKC biosampler for the collection of particles. The efficiency of the system was assessed based on the molecular determination of the viral load in the nebulizer after the aerosolization and in the aerosol collected at the end of the travel. Moreover, the residual infectivity was tested in vitro on the Vero E6 cell line, through the observation of the cytopathic effect (CPE), and the quantification of the viral load in the supernatants at 7 days post inoculation (dpi). A high RNA viral load was found in the SKC biosampler after aerosolization, indicating that it was possible to transport a high virus titer through the 30-cm chamber with all the dilutions (initial 105, 104, 103 plaque forming unit-PFU/mL). At the 7 dpi, an increment of the RNA viral load was determined for the dilutions 105 and 104 PFU/mL tested, while only the initial 105 PFU/mL resulted in visible CPE. Our findings allowed us to achieve the resilience of SARS-CoV-2 in aerosol form, at a concentration comparable to those reported for clinical samples. This mode of transmission should be considered for the mitigation and preventive measures to counteract SARS-CoV-2 spreading.

SARS-CoV-2 Short-Time Infection Produces Relevant Cytopathic Effects in Vero E6 Cell Line.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is mainly transmitted through respiratory droplets from positive subjects to susceptible hosts or by direct contact with an infected individual. Our study focuses on the in vitro minimal time of viral absorption as well as the minimal quantity of virus able to establish a persistent infection in Vero E6 cells. We observed that 1 min of in vitro virus exposure is sufficient to generate a cytopathic effect in cells after 7 days of infection, even at a multiplicity of infection (MOI) value of 0.01. Being aware that our findings have been obtained using an in vitro cellular model, we demonstrated that short-time exposures and low viral concentrations are able to cause infection, thus opening questions about the risk of SARS-CoV-2 transmissibility even following short contact times.

High fecal calprotectin levels are associated with SARS-CoV-2 intestinal shedding in COVID-19 patients: A proof-of-concept study.

BACKGROUND: One third of coronavirus disease 2019 (COVID-19) patients have gastrointestinal symptoms. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA has been detected in stool samples of approximately 50% of COVID-19 individuals. Fecal calprotectin is a marker of gastrointestinal inflammation in the general population. AIM: To investigate if fecal calprotectin correlates with SARS-CoV-2 intestinal shedding in COVID-19 patients with pneumonia. METHODS: Patients with SARS-CoV-2 pneumonia admitted to the Infectious Disease Unit (University Hospital of Trieste, Italy) from September to November 2020 were consecutively enrolled in the study. Fecal samples were collected and analyzed for quantification of fecal calprotectin (normal value < 50 mg/kg) and SARS-CoV-2 RNA presence by polymerase chain reaction (PCR). Inter-group differences were determined between patients with and without diarrhea and patients with and without detection of fecal SARS-CoV-2. RESULTS: We enrolled 51 adults (40 males) with SARS-CoV-2 pneumonia. Ten patients (20%) presented with diarrhea. Real-time-PCR of SARS-CoV-2 in stools was positive in 39 patients (76%), in all patients with diarrhea (100%) and in more than two thirds (29/41, 71%) of patients without diarrhea. Obesity was one of the most common comorbidities (13 patients, 25%); all obese patients (100%) (P = 0.021) tested positive for fecal SARS-CoV-2. Median fecal calprotectin levels were 60 mg/kg [interquartile range (IQR) 21; 108]; higher fecal calprotectin levels were found in the group with SARS-CoV-2 in stools (74 mg/kg, IQR 29; 132.5) compared to the group without SARS-CoV-2 (39 mg/kg, IQR 14; 71) (P < 0.001). CONCLUSION: High fecal calprotectin levels among COVID-19 patients correlate with SARS-CoV-2 detection in stools supporting the hypothesis that this virus can lead to bowel inflammation and potentially to the 'leaky gut' syndrome.

Molecular detection of SARS-CoV-2 from indoor air samples in environmental monitoring needs adequate temporal coverage and infectivity assessment.

The relevance of airborne exposure to SARS-CoV-2 in indoor environments is a matter of research and debate, with special importance for healthcare low-risk settings. Experimental approaches to the bioaerosol sampling are neither standardized nor optimized yet, leading in some cases to limited representativity of the temporal and spatial variability of viral presence in aerosols. Airborne viral viability moreover needs to be assessed. A study has been conducted collecting five 24-h PM10 samples in a COVID-19 geriatric ward in late June 2020, and detecting E and RdRp genes by RT-qPCR with a Ct between 36 and 39. The viral RNA detection at Ct = 36 was related to the maximal numerosity of infected patients hosted in the ward. Lacking a direct infectivity assessment for the collected samples an experimental model has been defined, by seeding twelve nasopharyngeal swab extracts from COVID-19 positive patients on Vero E6 cells; only the four extracts with a viral load above E+10 viral copies (approximately Ct<24) have been able to establish a persistent infection in vitro. Therefore, the cytopathic effect, a key feature of residual infectivity, could be considered unlikely for the environmental PM10 samples showing amplification of viral RNA at Ct = 36 or higher. A standardization of airborne SARS-CoV-2 long-term monitoring and of environmental infectivity assessment is urgently needed.

Blue photobiomodulation LED therapy impacts SARS-CoV-2 by limiting its replication in Vero cells.

The study of any intervention able to counteract SARS-CoV-2 pandemic is considerably envisaged. It was previously shown, in in vitro models of infections, that the LED blue light is able to decrease the viral load of HSV-1 and ZIKV. In our study, LED photobiomodulation therapy (PBMT) at blue wavelengths (450, 454 and 470 nm) was tested in an in vitro model of SARS-CoV-2 infection, employing three experimental settings: SARS-CoV-2 was irradiated and then transferred to cells; already infected cells were irradiated; cells were irradiated prior to infection. A decrement of the viral load was observed when previously infected cells were irradiated with all three tested wavelengths and relevant effects were registered especially at 48 hours post-infection, possibly suggesting that the blue light could interfere with the intracellular viral replication machinery. Our in vitro findings could represent the starting point for translational applications of PBMT as a supportive approach to fight SARS-CoV-2.

SARS-Cov-2RNA found on particulate matter of Bergamo in Northern Italy: First evidence.

BACKGROUND: The burden of COVID-19 was extremely severe in Northern Italy, an area characterized by high concentrations of particulate matter (PM), which is known to negatively affect human health. Consistently with evidence already available for other viruses, we initially hypothesized the possibility of SARS-CoV-2 presence on PM, and we performed a first experiment specifically aimed at confirming or excluding this research hyphotesys. METHODS: We have collected 34 PM10 samples in Bergamo area (the epicenter of the Italian COVID-19 epidemic) by using two air samplers over a continuous 3-weeks period. Filters were properly stored and underwent RNA extraction and amplification according to WHO protocols in two parallel blind analyses performed by two different authorized laboratories. Up to three highly specific molecular marker genes (E, N, and RdRP) were used to test the presence of SARS-CoV-2 RNA on particulate matter. RESULTS: The first test showed positive results for gene E in 15 out of 16 samples, simultaneously displaying positivity also for RdRP gene in 4 samples. The second blind test got 5 additional positive results for at least one of the three marker genes. Overall, we tested 34 RNA extractions for the E, N and RdRP genes, reporting 20 positive results for at least one of the three marker genes, with positivity separately confirmed for all the three markers. Control tests to exclude false positivities were successfully accomplished. CONCLUSION: This is the first evidence that SARS-CoV-2 RNA can be present on PM, thus suggesting a possible use as indicator of epidemic recurrence.

Searching for SARS-COV-2 on Particulate Matter: A Possible Early Indicator of COVID-19 Epidemic Recurrence.

A number of nations were forced to declare a total shutdown due to COVID-19 infection, as extreme measure to cope with dramatic impact of the pandemic, with remarkable consequences both in terms of negative health outcomes and economic loses. However, in many countries a "Phase-2" is approaching and many activities will re-open soon, although with some differences depending on the severity of the outbreak experienced and SARS-COV-2 estimated diffusion in the general population. At the present, possible relapses of the epidemic cannot be excluded until effective vaccines or immunoprophylaxis with human recombinant antibodies will be properly set up and commercialized. COVD-19-related quarantines have triggered serious social challenges, so that decision makers are concerned about the risk of wasting all the sacrifices imposed to the people in these months of quarantine. The availability of possible early predictive indicators of future epidemic relapses would be very useful for public health purposes, and could potentially prevent the suspension of entire national economic systems. On 16 March, a Position Paper launched by the Italian Society of Environmental Medicine (SIMA) hypothesized for the first time a possible link between the dramatic impact of COVID-19 outbreak in Northern Italy and the high concentrations of particulate matter (PM10 and PM2.5) that characterize this area, along with its well-known specific climatic conditions. Thereafter, a survey carried out in the U.S. by the Harvard School of Public Health suggested a strong association between increases in particulate matter concentration and mortality rates due to COVID-19. The presence of SARS-COV-2 RNA on the particulate matter of Bergamo, which is not far from Milan and represents the epicenter of the Italian epidemic, seems to confirm (at least in case of atmospheric stability and high PM concentrations, as it usually occurs in Northern Italy) that the virus can create clusters with the particles and be carried and detected on PM10. Although no assumptions can be made concerning the link between this first experimental finding and COVID-19 outbreak progression or severity, the presence of SARS-COV-2 RNA on PM10 of outdoor air samples in any city of the world could represent a potential early indicator of COVID-19 diffusion. Searching for the viral genome on particulate matter could therefore be explored among the possible strategies for adopting all the necessary preventive measures before future epidemics start.