Saliva, a relevant alternative sample for SARS-CoV2 detection

BackgroundCurrently, COVID-19 diagnosis relies on quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) from nasopharyngeal swab (NPS) specimens, but NPSs present several limitations. The simplicity, low invasive and possibility of self-collection of saliva imposed this specimen as a relevant alternative for SARS-CoV-2 detection. However, the discrepancy of saliva test results compared to NPSs made of its use controversial. Here, we proposed to assess Salivettes(R), as a standardized saliva collection device, and to compare SARS-CoV-2 positivity on paired NPS and saliva specimens. MethodsA total of 303 individuals randomly selected among those investigated for SARS-CoV-2 were enrolled, including 30 (9.9%) patients previously positively tested using NPS (follow-up group), 90 (29.7%) mildly symptomatic and 183 (60.4%) asymptomatic. ResultsThe RT-qPCR revealed a positive rate of 11.6% (n=35) and 17.2% (n=52) for NPSs and saliva samples, respectively. The sensitivity and specificity of saliva samples were 82.9% and 91.4%, respectively, using NPS as reference. The highest proportion of discordant results concerned the follow-up group (33.3%). Although in the symptomatic and asymptomatic groups the agreement exceeded 90.0%, 17 individuals were detected positive only in saliva samples, with consistent medical arguments. ConclusionSaliva collected with Salivette(R) demonstrated more sensitive for detecting symptomatic and pre-symptomatic infections.

Evolution of self-reactive IgG antibody repertoires in patients with relapsing-remitting multiple sclerosis.

We have previously demonstrated a distortion of self-reactive IgG antibody repertoires in patients with multiple sclerosis (MS) compared to controls, by immunoblotting assays, using human brain homogenates. The analysis of the immune profiles against human brain antigens allowed us to distinguish MS patients, and to associate a particular pattern of reactivity for each clinical form of MS. The aim of the present study was to evaluate the evolution of such patterns in patients with relapsing-remitting MS (RRMS). In a first step, we confirmed, by western blotting using human brains as source of antigens, the existence of specific repertoires of IgG reactivity in whole serum collected from healthy subjects (n = 32) and from untreated patients with RRMS (n = 56). In a second step, the evaluation of patterns was performed at baseline and 1 year later in untreated RRMS patients (n = 15), and in RRMS patients treated with IFN-beta (n = 41). In both groups, little change in IgG reactivity in whole serum was found. However, a higher degree of stability was noted in treated versus untreated patients (P < 0.01). Our results have showed a specific and relatively stable pattern of reactivity for each RRMS individual tested against brain antigens even after a 1-year treatment prevailing in treated patients suggesting that IFN-beta could stabilize IgG antibody repertoires.