RESUMO
We have determined SARS-CoV-2-specific antibody responses in a cohort of 96 individuals with acute infection and in 578 individuals enrolled in a seroprevalence population study in Switzerland including three groups, i.e. subjects with previous RT-PCR confirmed SARS-CoV-2 infections (n=90), positive patient contacts (n=177) and random selected subjects (n=311). SARS-CoV-2 antibody responses specific to the Spike (S), in the monomeric and native trimeric forms, and/or the nucleocapsid (N) proteins were equally sensitive in the acute infection phase. Interestingly, as compared to anti-S antibody responses, those against the N protein appear to wane in the post-infection and substantially underestimated the proportion of SARS-CoV-2 infections in the groups of patient positive contacts, i.e. 10.9 to 32.2% reduction and in the random selected general population, i.e. up to 45% reduction. The overall reduction in seroprevalence targeting only anti-N IgG antibodies for the total cohort ranged from 9.4 to 31%. Of note, the use of the S protein in its native trimer form was more sensitive as compared to monomeric S proteins. These results indicate that the assessment of anti-S IgG antibody responses against the native trimeric S protein should be implemented to estimate SARS-CoV-2 infections in population-based seroprevalence studies.
RESUMO
BackgroundThese last months, dozens of SARS-CoV-2 serological tests have become available with varying performances. A major effort was completed to compare 17 serological tests. MethodsIn a preliminary phase, we compared 17 IgG, IgM, IgA and pan Ig serological tests including ELISA, LFA, CLIA and ECLIA on a panel of 182 sera, comprising 113 sera from hospitalized patients with a positive RT-PCR, and 69 sampled before 1st November 2019, expected to give a positive and negative results, respectively. In a second phase, the five best performing and most available tests were further evaluated on a total of 582 sera (178 and 404 expected positive and negative, respectively), allowing the assessment of 20 possible cross-reactions with other virus. ResultsIn the preliminary phase, among eight IgG/pan-Ig ELISA or CLIA/ECLIA tests, four had a sensitivity and specificity above 90% and 98% respectively, and on six IgM/IgA tests, only one was acceptable. Only one LFA test on three showed good performances for both IgG and IgM. For all the tests IgM and IgG aroused concomitantly. In the second phase, no tests showed particular cross-reaction. We observed an important heterogeneity in the development of the antibody response, and that anti-nucleocapside (anti-N) antibodies appeared earlier than the anti-spike (anti-S) proteins. ConclusionsThe identified SARS-CoV-2 serology tests may be used for the diagnostic of CoviD-19 for negative RT-PCR patients presenting severe to mild suggestive symptoms or particular clinical presentation. Detection of both anti-N and anti-S could be complementary to increase the sensitivity of the analysis.
RESUMO
SARS-CoV-2 detection is mainly performed by RT-PCR but recently serological tests were made available. A first one month follow-up of the SARS-CoV-2 serology records was performed in our laboratory to precise the diversity and proportion of the SARS-CoV-2 serology test indications and to identify new valid indications (meningoencephalitis, vasculitis, ...)
