Development and comparative evaluation of SARS-CoV-2 S-RBD and N based ELISA tests in various African endemic settings.

Management of the COVID-19 pandemic relies on molecular diagnostic methods supported by serological tools. Herein, we developed S-RBD- and N- based ELISA assays useful for infection rate surveillance as well as the follow-up of acquired protective immunity against SARS-CoV-2. ELISA assays were optimized using COVID-19 Tunisian patients' sera and prepandemic controls. Assays were further validated in 3 African countries with variable endemic settings. The receiver operating curve was used to evaluate the assay performances. The N- and S-RBD-based ELISA assays performances, in Tunisia, were very high (AUC: 0.966 and 0.98, respectively, p < 0.0001). Cross-validation analysis showed similar performances in different settings. Cross-reactivity, with malaria infection, against viral antigens, was noticed. In head-to-head comparisons with different commercial assays, the developed assays showed high agreement. This study demonstrates, the added value of the developed serological assays in low-income countries, particularly in ethnically diverse populations with variable exposure to local endemic infectious diseases.

ABO blood groups and risk of covid-19.

INTRODUCTION: Coronavirus pandemic has been the subject of a large number of publications, some of which have shown an increased risk of contracting Covid-19 in carriers of blood group A. AIMS: In this study we looked at the profile of blood group phenotype of a series of Tunisian patients with covid-19 admitted to Abderrahman Mami hospital in Ariana . METHODS: Our study included 51 Tunisian patients with SARS-CoV-2 infection admitted to Abderrahmane Mami hospital between late march 2020 and early May 2020. The distribution of blood groups in Covid-19 patients was compared with that of a control group of 1506 patients with no Covid-19 infection as well as with the distribution of blood groups in a population of 63375 voluntary blood donors. RESULTS: Our series, although limited in size, showed a higher prevalence of blood group A among Covid-19 patients, statistically significant compared to ABO blood group distribution among Tunisian blood donors and among a control group of patients without Covid -19. CONCLUSION: these results are in line with data from the literature, particularly on larger series in China.

Antinuclear antibodies in interstitial lung disease: Prevalence and clinical significance.

INTRODUCTION: The diagnosis of interstitial lung disease (ILD) requires elimination of underlying connective tissue disease. Consequently, antinuclear antibodies (ANA) are routinely screened in patients with idiopathic interstitial pneumonia. However the clinical usefulness of this practice is not well clear. AIM: In this study, we evaluated the frequency of ANA in ILD's patients and investigated the clinical significance of the ANA's presence in these patients. METHODS: We conducted a retrospective study of hospitalized patients diagnosed ILD at pulmonary department and for which ANA was performed in the immunology laboratory of our institution. Demographic features, clinical symptoms, biological and radiologic findings and CTD-ILD diagnoses were compared between patients with positive ANA versus negative ANA. RESULTS: We enrolled 73 patients. The ANA's prevalence was 32%. There were no significant differences in demographics, pulmonary function test values and radiologic findings between patients with and without ANA. Patients with positive ANA had more cutaneous manifestations (p꞊0.011) and Raynaud's phenomenon (p꞊0.029). The diagnosis of connective tissue disease was made in 42% of patients with positive ANA versus 8% with negative ANA (p꞊ 0.001). ANA's titer higher than 1/320 was predictive of CTD diagnosis (OR꞊14.4) (p<0.001). CONCLUSIONS: The research of ANA in PID's patients is an important tool of CTD diagnosis specially in those with suggestive symptoms of autoimmune disease.

Computer-Assisted Classification Patterns in Autoimmune Diagnostics: The AIDA Project.

Antinuclear antibodies (ANAs) are significant biomarkers in the diagnosis of autoimmune diseases in humans, done by mean of Indirect ImmunoFluorescence (IIF) method, and performed by analyzing patterns and fluorescence intensity. This paper introduces the AIDA Project (autoimmunity: diagnosis assisted by computer) developed in the framework of an Italy-Tunisia cross-border cooperation and its preliminary results. A database of interpreted IIF images is being collected through the exchange of images and double reporting and a Gold Standard database, containing around 1000 double reported images, has been settled. The Gold Standard database is used for optimization of a CAD (Computer Aided Detection) solution and for the assessment of its added value, in order to be applied along with an Immunologist as a second Reader in detection of autoantibodies. This CAD system is able to identify on IIF images the fluorescence intensity and the fluorescence pattern. Preliminary results show that CAD, used as second Reader, appeared to perform better than Junior Immunologists and hence may significantly improve their efficacy; compared with two Junior Immunologists, the CAD system showed higher Intensity Accuracy (85,5% versus 66,0% and 66,0%), higher Patterns Accuracy (79,3% versus 48,0% and 66,2%), and higher Mean Class Accuracy (79,4% versus 56,7% and 64.2%).

Novel and recurrent AID mutations underlie prevalent autosomal recessive form of HIGM in consanguineous patients.

Immunoglobulin class switch recombination deficiencies (Ig-CSR-D) are characterized by normal or elevated serum IgM level and absence of IgG, IgA, and IgE. Most reported cases are due to X-linked CD40L deficiency. Activation-induced cytidine deaminase deficiency is the most frequent autosomal recessive form, whereas CD40 deficiency is more rare. Herein, we present the first North African study on hyper IgM (HIGM) syndrome including 16 Tunisian patients. Phenotypic and genetic studies allowed us to determine their molecular basis. Three CD40LG mutations have been identified including two novels (c.348_351dup and c.782_*2del) and one already reported mutation (g.6182G>A). No mutation has been found in another patient despite the lack of CD40L expression. Interestingly, three AICDA mutations have been identified in 11 patients. Two mutations were novel (c.91T>C and c.389A>C found in one and five patients respectively), and one previously reported splicing mutation (c.156+1T>G) was found in five patients. Only one CD40-deficient patient, bearing a novel mutation (c.109T>G), has been identified. Thus, unlike previous reports, AID deficiency is the most frequent underlying molecular basis (68%) of Ig-CSR-D in Tunisian patients. This finding and the presence of specific recurrent mutations are probably due to the critical role played by inbreeding in North African populations.

Multispecific anti neutrophil cytoplasm antibodies: a case report.

AIM: To report the presence af ANCA with an unusual polyreactivity. CASE REPORT: 50 year-old woman with pulmonary fibrosis whose immunological investigations showed the presence of ANCA with an unusual polyreactivity against several neutrophil proteins (PR3,MPO, BPI, lysozyme, elastase and cathepsine G) which could be related to a polyclonal hypergammaglobulinemia occurring in this patient. CONCLUSION: The international consensus on the testing of ANCA recommends seeking major specificities like MPO and PR3 which are good markers of ANCA-associated vasculitides. The use of multiantigenic ELISA can be helpful to detect various target antigens at the same time and may thus explain some atypical fluorescent patterns observed when searching for ANCA by Indirect immunofluorescence, these results, however, must be interpreted with caution.

Molecular characterization of a discrete hemoglobinopathy upon investigation for a lung hydatic cyst in an old Tunisian patient.

We report the case of an old Tunisian patient hospitalized for a complicated hydatic cyst of the right lung. Primary laboratory investigation showed a microcytic hypochromic anemia with an abnormal hemoglobin pattern. Hemoglobin analysis and DNA sequencing of the ß-globin gene revealed a compound heterozygote, HbO-Arab/cd 39 ß°-thalassemia. This hemoglobinopathy was never diagnosed earlier. It spent undiagnosed until the patient presented with hydatic cyst. Coexistence of the two pathologies complicated the general state of the patient and led to a severe anemia. The patient has undergone a surgical therapy for the hydatic cyst and was advised to start a follow up for her hemoglobinopathy.