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1.
Topics in Antiviral Medicine ; 29(1):53-54, 2021.
Article in English | EMBASE | ID: covidwho-1250660

ABSTRACT

Background: Further knowledge on adaptive immunity to SARS-CoV-2 (CoV-2) in children is needed in order to define possible immunization strategies and reconsider pandemic control measures. We analyzed anti-CoV-2 antibodies (Ab) and their neutralizing activity (PRNT), alongside antigen (Ag) specific cellular response, in relation to virus load in nasopharyngeal swabs. Methods: We analysed 42 CoV-2 patients at 7 days after symptoms onset. CoV-2 viral load (VL) was measured by RT-PCR and digital droplet PCR on longitudinal samples of nasopharyngeal swabs (NP). Virus infectivity (FFU) was tested by virus focus forming assay. CoV-2 antibodies were investigated by Diasorin (CoV-2 Ab) and neutralization assay (PRNT). CoV-2-specific CD4-CD40L+ T-cells and Spike specific B-cells were analysed by flow cytometry. Plasma proteomic profiling was measured by 2 Olink panels. We calculated the area under the curve (AUC) of the viral load from NP collected every 48 hours up to undetectable VL. Mann-Whitney was used to compare means in individuals with neutralizing activity (PRNT+) or not (PRNT-);linear regression was used to evaluate the associations between virus load and infectivity over time. Principal component analysis (PCA) was used to analyse proteomic data. Results: Higher VL was found in seronegative patients expressed in terms of both CoV-2 Ab (p=0.003) and PRNT (p=0.0007). Similarly, lower FFU was associated with higher CoV-2 Ab (p=0.003;rho=-0.67) and PRNT (p=0.023;rho=-0.46). Further, the AUC of the viral load in NP showed an inverse correlation with CoV-2 Ab (p=0.031;rho=-0.54). Development of humoral response was associated with the presence of CoV-2 specific IgD-CD27+ B cells, with a higher frequency of CoV-2 specific B cells found in seropositive compared to seronegative (p=0.001). Besides, individuals developing neutralizing Ab had higher frequency CD4-CD40L+ T-cells compared to PRNT- (p=0.03). The plasma proteome confirmed the association between cellular and humoral CoV-2 immunity, with PRNT+ showing higher viral signal transduction molecules (SLAMF1, CD244, CLEC4G). Conclusion: This work provides a virological and immunological characterization of SARS-CoV-2 infected children presenting a differential Abmediated neutralizing activity. It demonstrates that children with neutralizing antibodies present reduced viral load, faster virus clearance and lower in vitro infectivity. These data provide information that can drive vaccination endpoints and quarantine measures policies.

2.
Topics in Antiviral Medicine ; 29(1):239-240, 2021.
Article in English | EMBASE | ID: covidwho-1250055

ABSTRACT

Background: SARS-CoV-2 (CoV-2) infected children often range from being paucysymptomatic to fully asymptomatic. The impact of this population on the epidemics due to their ability to transmit the virus and achieve protective immunity has been poorly defined. We explored CoV-2 infectivity potential and anti-CoV-2 cellular (CD8, NK and B) and humoral response in symptomatic (SY) and asymptomatic (AS) CoV-2 infected children, screened for a family member resulted infected. Methods: CoV-2 viral load was measured by RT-PCR and digital droplet PCR (ddPCR) on longitudinal samples of nasopharyngeal swabs in 9 AS and 33 SY (samples were paired according to symptoms'onset for SY and first family contact for AS). Virus infectivity was tested by Virus focus forming assay (FFA). CoV-2 antibodies were investigated by Diasorin (CoV-2 Ab) and Ab-mediated neutralization activity (PRNT) at diagnosis, (samples collected >5 days from symptoms onset in SY, or from first family contact in AS were excluded from this timepoint), and in the convalescent phase (CP) (10-14 days after infection). Cellular response was analyzed by flow cytometry: 1) Ag-specific B cells, by a S1+S2 CoV2-R-PE probe;2) Ag-specific CD8+T cells by ICAM+;3) natural-killer (NK) phenotype. Mann-Whitney was used for comparison;linear regression was used to evaluate the associations between virus load and infectivity. Results: AS showed lower viral load (p=0.004) and faster virus clearance (p=0.0002) compared to SY. Virus infectivity was associated with ddPCR (rho=0.66;p=0.002). ASY and SY showed similar levels of CoV-2 Ab and PRNT, at both diagnosis and at follow up. During the CP, the proportion of CoV-2 Ab negative was 33,3% for both groups and PRNT was negative in 16,6% and 15,7% of AS and SY respectively. Anti-CoV-2 cellular immunity was comparable between ASY and SY. Indeed Ag-specific B cells and CD8 T cells were detectable despite symptomatology and no major differences were found between the groups. Total NK frequency was similar between the groups, while a regulatory NK subset (CD56bright NK cells) was higher in AS compared to SY (p=0.01). Conclusion: These data show that AS have a lower infectivity potential compared to SY suggesting that mitigated restrictive measures or alternative screening may be considered for this population. In addition, these patients showed an intact ability to produce humoral and cellular CoV-2 specific responses hence contributing to achieve herd immunity as much as SY.

3.
Biochimica Clinica ; 44(SUPPL 2):S103, 2020.
Article in English | EMBASE | ID: covidwho-984242

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) is the etiological agent of Coronavirus Disease 2019 (COVID-19), rapidly spread in the current pandemic. The diagnosis of Covid 19 is based on the detection of viral RNA by molecular amplification (NAAT) in nasopharingeal swabs and virus-specific antibodies of different isotypes in the serum. IgM and IgG anti-Sars CoV-2 appear 4-7 days after the onset of symptoms but the highest level of IgM and IgG are detected after 2-3 weeks and 3-6 weeks, respectively. Serological assays are useful for the diagnosis and for epidemiological studies. To compare different methods, we measured serum antibody levels with three automated assays including Elecsys®Roche anti-SarsCov2, Abbott Sars-CoV-2 IgG and Diasorin Liason®SARS-CoV-2 S1/S2 IgG in a goup of 50 selected subjects (negative or positive for nasopharingeal swab, initial screening with Abbott serological test or previuos clinical suspect of COVID-19). A good concordance of the results (68%) was found between Roche and Diasorin assays, and between Roche and Abbott tests while the concordance between Abbott and Diasorin is lower (38%). The samples were also analyzed with other 2 non automated assays: Euroimmun Sars-CoV-2 ELISA (IgG) and Euroimmun Sars-CoV-2 ELISA (IgA). The percentage of positivity is 58% with Diasorin Liason®SARS-CoV-2 S1/S2 IgG, 42% for Abbott Sars-CoV-2 IgG, 32% for Euroimmun Sars-CoV-2 ELISA (IgA), 30% for Euroimmun Sars-CoV-2 ELISA (IgG) and 28% for Elecsys® Roche anti-SarsCov2. The concordance of ~88% and 86% was revealed between Roche test and Euroimmun (IgG), and between Roche and Euroimmun (IgA), respectively, while it reduced to 66% among Diasorin and Euroimmun (IgG) and 62% between Abbott and Euroimmune (IgG).The results in agreement with all five tests were the 34% of total selected cases. The percentage of positive specimens tested with Roche method confirmed with at least 2 other assays was 100%;this value was 93% for Euroimmun (IgG), 81% for Euroimmun (IgA), 52% for Diasorin assay and 47% for Abbott test.

5.
J Eur Acad Dermatol Venereol ; 34(11): 2620-2629, 2020 Nov.
Article in English | MEDLINE | ID: covidwho-436973

ABSTRACT

BACKGROUND: Acral chilblain-like lesions are being increasingly reported during COVID-19 pandemic. However, only few patients proved positivity for SARS-CoV-2 infection. The relationship between this skin manifestation and COVID-19 infection has not been clarified yet. OBJECTIVE: To thoroughly characterize a prospective group of patients with chilblain-like lesions and to investigate the possible relationship with SARS-CoV-2 infection. METHODS: Following informed consent, patients underwent (i) clinical evaluation, (ii) RT-PCR and serology testing for SARS-CoV-2, (iii) digital videocapillaroscopy of finger and toe nailfolds, (iv) blood testing to screen for autoimmune diseases and coagulation anomalies, and (v) skin biopsy for histopathology, direct immunofluorescence and, in selected cases, electron microscopy. RESULTS: Nineteen patients, all adolescents (mean age: 14 years), were recruited. 11/19 (58%) of them and/or their cohabitants reported flu-like symptoms one to two months prior to skin manifestation onset. Lesions were localized to toes and also heels and soles. Videocapillaroscopy showed pericapillary oedema, dilated and abnormal capillaries, and microhaemorrhages both in finger and toe in the majority of patients. Major pathological findings included epidermal basal layer vacuolation, papillary dermis oedema and erythrocyte extravasation, perivascular and perieccrine dermal lymphocytic infiltrate, and mucin deposition in the dermis and hypodermis; dermal vessel thrombi were observed in two cases. Blood examinations were normal. Nasopharyngeal swab for SARS-CoV-2 and IgG serology for SARS-CoV-2 nucleocapsid protein were negative. Importantly, IgA serology for S1 domain of SARS-CoV-2 spike protein was positive in 6 patients and borderline in 3. CONCLUSIONS: Chilblain-like lesions during COVID-19 pandemic have specific epidemiologic, clinical, capillaroscopic and histopathological characteristics, which distinguish them from idiopathic perniosis. Though we could not formally prove SARS-CoV-2 infection in our patients, history data and the detection of anti-SARS-COV-2 IgA strongly suggest a relationship between skin lesions and COVID-19. Further investigations on the mechanisms of SARS-CoV-2 infection in children and pathogenesis of chilblain-like lesions are warranted.


Subject(s)
COVID-19/complications , Chilblains/virology , Adolescent , Biopsy , COVID-19/epidemiology , COVID-19 Testing , Female , Humans , Italy/epidemiology , Male , Pandemics , Prospective Studies , SARS-CoV-2
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