Comparative evaluation of serological protection against SARS-CoV-2: sinopharm vaccine versus convalescent plasma

Introducere. Pandemia de COVID-19 a avut un impact global devastator. În acest context, disponibilitatea timpurie a vaccinurilor eficiente, cum ar fi Sinopharm, a fost esențială pentru gestionarea crizei. Scopul lucrării. Acest studiu a evaluat eficacitatea vaccinului Sinopharm BBIBP-CorV, măsurând anticorpii anti-Spike RBD IgG și potențialul de neutralizare a plasmei convalescente COVID-19 și serului adulților din Republica Moldova vaccinați cu Sinopharm. Material și metode. Au fost dezvoltate teste ELISA și de neutralizare bazate pe pseudovirus pentru a evalua prezența și eficacitatea anticorpilor împotriva SARS-CoV-2. Rezultate. Analiza noastră a arătat o corelație semnificativă moderată între titrurile de IgG și nivelurile generale de neutralizare. A fost observată o corelație mai mare în rândul indivizilor convalescenți, comparativ cu cei vaccinați. Persoanele care s-au recuperat de infecția COVID-19 au dezvoltat niveluri mai ridicate de anticorpi IgG anti-RBD Spike. Cu toate acestea, vaccinul Sinopharm a generat un răspuns imun mai sustenabil, indivizii vaccinați producând niveluri mai ridicate de anticorpi neutralizanți. Concluzii. Rezultatele indică faptul că, deși ambele grupe au dezvoltat un răspuns imun, există o diferență notabilă între protecția oferită de vaccinul Sinopharm și cea oferită de plasma convalescentă. În ciuda avantajelor inițiale ale plasmei convalescente, vaccinul Sinopharm pare să ofere o protecție serologică mai puternică împotriva SARS-CoV-2. Rezultatele noastre subliniază importanța continuării cercetărilor pentru a optimiza strategiile de protecție serologică împotriva acestui virus.Background. The COVID-19 pandemic has had a devastating global impact. In this context, the early availability of effective vaccines, such as Sinopharm, was essential for managing the crisis. Objective of the study. This study evaluated the efficacy of Sinopharm BBIBP-CorV vaccine by measuring anti-Spike RBD IgG antibodies and neutralization potential of COVID-19 convalescent plasma and Moldovan serum of adults vaccinated with Sinopharm. Material and methods. ELISA and pseudovirus-based neutralization assays have been developed to assess the presence and efficacy of antibodies against SARS-CoV-2. Results. Our analysis showed a moderate significant correlation between IgG titers and overall neutralization levels. A higher correlation was observed among convalescent compared to vaccinated individuals. Individuals who recovered from COVID-19 infection developed higher levels of anti-RBD Spike IgG antibodies. However, the Sinopharm vaccine elicited a more sustainable immune response, with vaccinated individuals producing higher levels of neutralizing antibodies. Conclusion. The results suggest that although both groups developed an immune response, there is a notable difference between the protection provided by the Sinopharm vaccine and that provided by convalescent plasma. Despite the initial advantages of convalescent plasma, the Sinopharm vaccine appears to provide stronger serological protection against SARS-CoV-2. Our results highlight the importance of further research to optimize serological protection strategies against this virus

Development of a flow cytometry-based method to detect neutralising antibodies in SARS-CoV-2 infection

Introduction. The ongoing COVID-19 pandemic caused by SARS-CoV-2 has led to significant morbidity and mortality worldwide, underscoring the need for effective diagnostic and therapeutic tools. Neutralizing antibodies are essential components of the immune response to viral infections and play a crucial role in controlling and preventing the spread of SARS-CoV-2. The development of sensitive and specific assays for the detection of neutralizing antibodies is, therefore, crucial for the evaluation of vaccine and therapeutic candidates. In this study, a flow cytometry- based method was developed for the detection of neutralizing antibodies in individuals infected with SARS-CoV-2. Material and methods. To achieve this, a lentivector system was used to prepare SARS-CoV-2 Spike pseudoviruses expressing Green Fluorescent Protein (GFP) protein. HEK-293T cells were transfected with three plasmids: pLVTHM coding for a GFP reporter, the packaging plasmid psPAX2, and pCDNA3 carrying the D614G SPIKEΔCyto mutation. The infection efficiency was determined by measuring the percentage of GFP-positive cells using a cytofluorimeter (BD Accuri C6) and analyzed using FlowJo software V10 (BD). The neutralization titre was expressed as the reciprocal dilution at which 50% of infection reduction was achieved. The assay was evaluated using 3 cohorts: (i) 100 individuals who recovered from COVID-19; (ii) 100 Sinopharm vaccinated recipients; (iii) 96 pre-pandemic healthy-donors. Results. After being mixed and pre-incubated for two hours with an equal amount of SARS-CoV-2 pseudotyped lentivirus, samples were examined in duplicate at three different dilutions (1:10, 1:50, and 1:250). To determine the sample's neutralizing antibody content, the mixture was then added to the target cells and incubated for 72 hours. According to analyses, the green fluorescence background for untransduced cells ranged from 0.2% to 0.5% across all cohorts. Between 28% and 40% of cells were transduced by the SARS-CoV-2 lentivirus, with or without pre-Covid sera. The outcomes showed high sensitivity and specificity. Moreover, this study demonstrated that the assay could be used to evaluate the neutralizing activity of monoclonal antibodies and convalescent plasma from individuals who have been immunized or recovered from COVID-19. The flow cytometry-based method developed in this study offers a reliable and efficient method for measuring neutralizing antibody responses to SARS-CoV-2 infection. The use of pseudoviruses expressing GFP allows easy detection and quantification of neutralizing antibodies, making it a valuable tool for evaluating vaccine and therapeutic candidates. Conclusions. Overall, this study provides a significant contribution to the development of effective diagnostic and therapeutic tools against SARS-CoV-2. The flow cytometry-based method offers a reliable and sensitive way to measure neutralizing antibody responses and has potential implications for the evaluation of vaccine efficacy and the development of convalescent plasma therapies. Overall, this method can aid in the fight against COVID-19 and the development of effective interventions to control the spread of the virus

Development of a flow cytometry-based method to detect neutralising antibodies in SARS-CoV-2 infection

Introduction. The ongoing COVID-19 pandemic caused by SARS-CoV-2 has led to significant morbidity and mortality worldwide, underscoring the need for effective diagnostic and therapeutic tools. Neutralizing antibodies are essential components of the immune response to viral infections and play a crucial role in controlling and preventing the spread of SARS-CoV-2. The development of sensitive and specific assays for the detection of neutralizing antibodies is, therefore, crucial for the evaluation of vaccine and therapeutic candidates. In this study, a flow cytometry-based method was developed for the detection of neutralizing antibodies in individuals infected with SARS-CoV-2. Material and methods. To achieve this, a lentivector system was used to prepare SARS-CoV-2 Spike pseudoviruses expressing Green Fluorescent Protein (GFP) protein. HEK-293T cells were transfected with three plasmids: pLVTHM coding for a GFP reporter, the packaging plasmid psPAX2, and pCDNA3 carrying the D614G SPIKEΔCyto mutation. The infection efficiency was determined by measuring the percentage of GFP-positive cells using a cytofluorimeter (BD Accuri C6) and analyzed using FlowJo software V10 (BD). The neutralization titre was expressed as the reciprocal dilution at which 50% of infection reduction was achieved. The assay was evaluated using 3 cohorts: (i) 100 individuals who recovered from COVID-19; (ii) 100 Sinopharm vaccinated recipients; (iii) 96 pre-pandemic healthy-donors. Results. After being mixed and pre-incubated for two hours with an equal amount of SARS-CoV-2 pseudotyped lentivirus, samples were examined in duplicate at three different dilutions (1:10, 1:50, and 1:250). To determine the sample's neutralizing antibody content, the mixture was then added to the target cells and incubated for 72 hours. According to analyses, the green fluorescence background for untransduced cells ranged from 0.2% to 0.5% across all cohorts. Between 28% and 40% of cells were transduced by the SARS-CoV-2 lentivirus, with or without pre-Covid sera. The outcomes showed high sensitivity and specificity. Moreover, this study demonstrated that the assay could be used to evaluate the neutralizing activity of monoclonal antibodies and convalescent plasma from individuals who have been immunized or recovered from COVID-19. The flow cytometry-based method developed in this study offers a reliable and efficient method for measuring neutralizing antibody responses to SARS-CoV-2 infection. The use of pseudoviruses expressing GFP allows easy detection and quantification of neutralizing antibodies, making it a valuable tool for evaluating vaccine and therapeutic candidates. Conclusions. Overall, this study provides a significant contribution to the development of effective diagnostic and therapeutic tools against SARS-CoV-2. The flow cytometry-based method offers a reliable and sensitive way to measure neutralizing antibody responses and has potential implications for the evaluation of vaccine efficacy and the development of convalescent plasma therapies. Overall, this method can aid in the fight against COVID-19 and the development of effective interventions to control the spread of the virus

A high-content imaging-based technique for detecting neutralizing antibodies in SARS-CoV-2 infection

Introduction. The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a profound impact on global health, with millions of confirmed cases and deaths worldwide. Conventional methods for detecting neutralizing antibodies rely on laborious and timeconsuming plaque reduction neutralization tests (PRNT), which require live virus and biosafety level 3 (BSL-3) facilities. Alternative methods have been developed, such as ELISA and pseudovirus neutralization assays, but these methods also have limitations regarding sensitivity and specificity. Therefore, there is a need for more efficient and sensitive techniques to detect neutralizing antibodies in SARS - CoV-2 infection. Aim. This study aimed to develop and evaluate a high-content imaging-based technique for detecting neutralizing antibodies in SARS-CoV-2 infection. Material and methods. In this experiment, the Huh7 - hACE2 cells were infected with the pseudotyped SARS-CoV-2 lentivirus expressing GFP protein and then incubated with serum or plasma from individuals who had been infected with the virus or vaccinated against it. If the serum or plasma contained neutralizing antibodies, they would bind to the spike protein of the virus and prevent it from entering the cells, resulting in a lower number of GFP-expressing cells. The cells were then stained with DAPI, a fluorescent dye that binds to DNA and allows the visualization of cell nuclei. The number of GFP-expressing cells, the intensity of DAPI staining in each cell, and the presence and levels of neutralizing antibodies in the serum or plasma samples were determined using high-content imaging microscopy (Operetta). The images were analysed using Columbus Image Data Storage and Analysis System to quantify the number of cells infected with the pseudotyped SARS-CoV-2 lentivirus expressing GFP protein. Results. We evaluated the performance of the high-content imaging-based technique by testing serum or plasma samples from 50 individuals with confirmed SARS-CoV-2 infection and 50 individuals who were not infected with the virus. The results showed that the technique had a sensitivity of 92% and a specificity of 98%, indicating high accuracy in detecting neutralizing antibodies. The technique also allowed us to quantify the levels of neutralizing antibodies in the samples, which varied among individuals. Conclusions. This technique has the potential to provide a more accurate and efficient way of identifying individuals with neutralizing antibodies, which could be crucial for vaccine development and epidemiological studies. The technique offers several advantages over conventional methods, including high sensitivity and specificity. It also allows for the simultaneous detection of multiple types of antibodies, providing a more comprehensive understanding of the immune response to SARS-CoV-2 and the potential for high throughput. The development of this technique has important implications for understanding immune responses to SARS-CoV-2, developing effective vaccines and therapies, and ultimately controlling the spread of COVID-19

Cyanobacteria pigments: potential alternatives against antibiotic-resistant bacteria

Department of Microbiology, Virology and Immunology, Nicolae Testemitanu State University of Medicine and Pharmacy, Chisinau, Republic of Moldova, The 8th International Medical Congress for Students and Young Doctors, September 24-26, 2020Introduction. The increasing number of multidrug-resistant bacteria in the last decade has left clinicians with very few medication options, usually resulting in the use of more expensive treatments. The demand of new therapeutic approaches encourages the discovery of new natural products with possible antimicrobial activity. Aim of the study. Therefore, the aim of this study was to look for active substances that could be used as antibacterial agents. To achieve this objective, two different fractions (myxoxantophyll and phycocyanin) from Spirulina platensis were investigated. Myxoxanthophyll is a carotenoid glycoside yellowish pigment present in the photosynthetic apparatus of Arthrospira (Spirulina) platensis and phycocyanin is a protein complex, accessory pigment to chlorophyll also present in Spirulina platensis. Materials and methods. The cyanobacteria extracts were tested in vitro for their antibacterial proprieties against (Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and coagulase-negative staphylococci) using macro dilution method Ericsson and Sheris. The Time-kill kinetics assay (CLSI M26) was used to study the bactericidal activity of the Spirulina platensis extracts against bacterial strains over the time. Results. By means of the broth macro dilution assay, it was found that microalga extracts possess pronounced antibacterial activity against Acinetobacter baumannii (MIC: 0,0275 mg/ml for myxoxanthophyll and 0,18 mg/ml for phycocyanin). In the case of coagulasenegative staphylococci the antimicrobial activity of Arthrospira platensis fractions was low. Gram-negative bacteria showed to be more sensitive to the action Spirulina platensis pigments than Gram-positive bacteria. Also, it was found that myxoxanthophyll possess bacteriostatic and bactericidal action at a lower concentration than the phycocyanin. At a concentration of 0,04 mg/ml myxoxantophyll could kill 100% bacteria in approximately 4 hours, and the timekill for phycocyanin was about 8 hours at the concentration 0,72 mg/ml. Conclusions. Further in vivo studies are required to investigate Spirulina platensis fractions potential toxic effects. In particular researches are needed to evaluate the use of control-release formulations in order to maintain the Arthrospira platensis pigments concentrations at antibacterial active doses

COVID-19 – тесты нейтрализации

Rezumat Studiile privind seroprevalența recent publicate demonstrează că, într-o populație randomizată, incidența SARS-CoV-2 constituie aproximativ 5%. Lupta cu pandemia ”COVID-19” va depinde de testarea anticorpilor neutralizanți, indiferent dacă aceștia au apărut ca rezultat al expunerii la virus sau sunt induși de vaccin. Scopul acestei sinteze a fost de a elucida disponibilitatea sau existența unor teste ce ar permite studierea prezenței anticorpilor neutralizanți la pacienții infectați cu SARS-CoV-2. Revizuirea literaturii a fost realizată accesând baza de date ”Scopus” (în conformitate cu cadrul metodologic sugerat de Arksey și O´Malley, anul 2005) și folosind motorul de căutare ”GoogleScholar”. Au fost analizate 22 de articole publicate înainte de 1 iunie 2020, în vederea studierii existenței metodelor de testare a anticorpilor neutralizanți față de SARS-CoV-2. Standardul de aur de testare a anticorpilor neutralizanți include utilizarea virusului, care în cazul SARSCoV-2 va necesita facilități de biosecuritate BSL-3. Un studiu publicat recent ne oferă o abordare cu totul nouă, care poate fi realizată în laboratoarele BSL-2. Două soluții pot fi considerate în acest sens: pseudovirusurile și virusurile-surogat. Pseudovirusurile pot realiza un singur ciclu de infecție, deoarece își pierd capacitatea de autoreplicare, fiind, astfel, mai sigure din punct de vedere biologic decât virusurile infecțioase. În cazul unui test de neutralizare a virusului-surogat pentru SARS-CoV-2, surogatul ar imita receptorul de legare al virusului. Cuantificarea anticorpilor neutralizanți este importantă pentru a evalua imunitatea postinfecțioasă.Summary Recently published seroprevalence studies indicate that in a randomized population the incidence of SARS-CoV-2 is approximately 5%. The road out of the ”COVID-19” pandemic will depend on the testing for neutralizing antibodies; whether they resulted from virus exposure, or they are vaccine induced. The aim of this review was to elucidate the availability or the existence of tests that would allow the study of the presence of neutralizing antibodies in patients infected with SARS-CoV-2. The literature review was performed by accessing the ”Scopus” database (according to the methodological framework suggested by Arksey and O´Malley, year 2005) and the ”GoogleScholar” search engine. We analyzed 22 articles published before June 1, 2020, in order to study the existence of methods for testing neutralizing antibodies to SARS-CoV-2. The gold standard for neutralizing antibody testing includes the use of the virus, which in the case of SARS-CoV-2 will require BSL-3 biosecurity facilities. A recently published study offers a completely new approach that can be done in BSL-2 laboratories. Two solutions can be considered in this regard: pseudoviruses and surrogate viruses. Pseudoviruses can perform a single cycle of infection because they lose their ability to self-replicate, thus being safer from a biological point of view than infectious viruses. In the case of a SARS-CoV-2 surrogate virus neutralization test, the surrogate would mimic the virus binding receptor. Quantification of neutralizing antibodies will be important to assess post-infectious immunity.Резюме Недавно опубликованные исследования серопревалентности показывают, что в общей популяции заболеваемость SARS-CoV-2 составляет приблизительно 5%. Выход из пандемии ”COVID-19” будет зависеть от тестирования на нейтрализующие антитела, возникшие в результате непосредственного воздействия вируса или после вакцинации. Целью обзора являлось выяснение доступности или существования тестов, которые позволили бы изучить наличие нейтрализующих антител у пациентов, инфицированных SARS-CoV-2. Обзор литературы осуществлен путем доступа к базе данных ”Scopus” (согласно методологической структуре предложенной Arksey и O´Malley, год 2005) и поисковой системе ”GoogleScholar”. Мы проанализировали 22 статьи, опубликованные до 1 июня 2020 г., чтобы изучить существование методов тестирования нейтрализующих антител к SARS-CoV-2. Золотым стандартом тестирования нейтрализующих антител является использование вируса, который в случае SARS-CoV-2 требует средств биологической защиты BSL-3. Недавно опубликованное исследование предлагает совершенно новый подход, который может быть реализован в лабораториях BSL-2. В данном случае возможны два решения: псевдо-вирусы и суррогатные вирусы. Псевдовирусы могут выполнить только один цикл заражения, поскольку теряют способность к самовоспроизведению, что делает их более безопасными с биологической точки зрения, чем инфекционные вирусы. В случае теста нейтрализации суррогатного вируса SARS-CoV-2, суррогат будет имитировать рецептор, связывающий вирус. Количественная оценка нейтрализующих антител важна для оценки постинфекционного иммунитета

Bacteriological control of quality compliance of sanitary – antiepidemic regime in health care institutions of mun. Chisinau during 2006 – 2009

Catedra de Microbiologie, virusologie şi imunologie USMF “Nicolae Testemiţanu”, Centrul de Sănătate Publică mun.ChişinăuBacteriological control of quality compliance of sanitary – antiepidemic regime in health care institutions of mun. Chisinau during 2006 – 2009 This study includes data about quality assurance of the sanitary anti-epidemic regime in IMS of Chisinau city during the period of 4 years (2006-2009). It was analyzed the quality of medical articles sterilization, the effectiveness of surface disinfection and indoor air purity, which were unsatisfactory as sanitary-microbiological indicators. Prezentul studiu include date privind calitatea asigurării regimului sanitaro–antiepidemic în IMS din municipiul Chişinău pe parcursul unei perioade de 4 ani (2006- 2009). S-a evaluat calitatea sterilizării articolelor medicale, eficienţa dezinfecţiei suprafeţelor şi a purităţii aerului din încăperile instituţiilor medico–sanitare, care au fost nesatisfăcătoare conform indicatorilor sanitaro–microbiologici

Biology of SARS-CoV-2 virus: narrative review

Catedra de biologie moleculară, Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu”, Chişinău, Republica Moldova, Computational Biology of Aging Group, Institutul de Biochimie al Academiei Române, Bucureşti, RomâniaRezumat Introducere. Un nou sindrom respirator acut sever (SARS) determinat de SARS-CoV-2 a apărut recent şi se răspândeşte rapid la om, provocând COVID-19. Material şi metode. Au fost analizate 38 de articole relevante actuale la tema cercetată. Rezultate. În articolul dat, a fost analizată poziţia taxonomică a virusului, particularităţile de organizare a genomului, ciclul vital al virusului. Genomul SARS-CoV-2 prezintă un grad înalt de similaritate cu alte virusuri care cauzează patologii similare SARS-COVID, MERS-COVID. Un rol aparte este acordat proteinelor virale, în special proteinei Spike, care se uneşte la receptorul enzimei de conversie a angiotensinei 2, determinând pătrunderea virusului în celula gazdă la oameni. Proteina S poate avea un potenţial înalt pentru designul preparatelor antivirale. Concluzii. S-au înregistrat progrese semnificative în studierea multilaterală a genomului SARS-CoV-2, fapt ce permite identificarea exactă a virusului şi determină dezvoltarea medicamentelor şi a vaccinurilor pentru tratamentul COVID-19. Cooperarea diferitor instituţii, centre ştiinţifice, guverne şi companii farmaceutice este necesară pentru a preveni răspândirea în continuare a COVID-19 şi identificarea soluţiilor de tratament.Abstract Introduction. A new severe acute respiratory syndrome (SARS) caused by SARS-CoV-2 has emerged recently and is spreading rapidly in humans, causing COVID-19. Material and methods. Thirty-eight current relevant articles on the researched topic were analyzed. Results. In this article, we analyzed the taxonomic position of the virus, the particularities of genome organization, and the life cycle of the virus. The SARS-CoV-2 genome has a high degree of similarity to other viruses that cause similar pathologies: SARS-CoV, MERS-CoV. A special role is given to viral proteins, especially Spike protein, which binds to the angiotensin 2 conversion enzyme receptor, causing the virus to enter the human host cell. The Spike protein can have a high potential for the design of antiviral drugs. Conclusions. Important progress was achieved in the multilateral study of the SARS-CoV-2 genome, which allows the exact identification of the virus and leads to the development of drugs and vaccines for the treatment of COVID-19. Cooperation between various institutions, scientific centers, governments, and pharmaceutical companies is needed to prevent the further spread of COVID-19 and to identify treatment solutions

Screening, Diagnostic and Prognostic Tests for COVID-19: A Comprehensive Review

From MDPI via Jisc Publications RouterHistory: accepted 2021-06-10, pub-electronic 2021-06-14Publication status: PublishedWhile molecular testing with real-time polymerase chain reaction (RT-PCR) remains the gold-standard test for COVID-19 diagnosis and screening, more rapid or affordable molecular and antigen testing options have been developed. More affordable, point-of-care antigen testing, despite being less sensitive compared to molecular assays, might be preferable for wider screening initiatives. Simple laboratory, imaging and clinical parameters could facilitate prognostication and triage. This comprehensive review summarises current evidence on the diagnostic, screening and prognostic tests for COVID-19

SARS-CoV-2 molecular evolution and human immune response to infection: Summary of doctoral thesis in medical sciences: 313.02. Medical microbiology, virology

Actuality and importance of the researched problem The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in December 2019 and quickly spread globally, causing the COVID-19 pandemic [1]. March 11th, 2023, the pandemic has caused over 760.4 million confirmed casesand6,8million deaths globally [2]. Since the outbreak, the virus has undergone rapid evolution, leading to the emergence of several variants of concern (VOCs) that are more transmissible, virulent, and potentially resistant to immunity induced by natural infection or vaccination. Up to date, the following VOCs were detected: alpha (B.1.1.7), beta (B.1.351), gamma (P.1), delta (B.1.617.2) and omicron (B.1.1.529, BA.2, BA.4, BA.5) [3,4] the first variants have been de-escalated as no more circulating. Understanding the molecular evolution of SARS-CoV-2 and the human immune response to infection is critical for developing effective strategies to combat the virus and protect public health [5,6]. Genomic sequencing allows real-time monitoring of viral transmission dynamics by tracking sequences that aggregate together in clusters and correlating them with clinical and epidemiological data [7,8]. These data are necessary to timely inform public health about the emergence of VOCs’ allowing an efficacious response [9]. On 7 March 2020, the first confirmed case of SARS-CoV-2 infection was registered in the Republic of Moldova [10,11]. In one month, the number of infected people increasedto965,with 854 cases transmitted locally and 111 imported [11,12]. Up to date (July 17, 2023), there have been 620.758 confirmed COVID-19 cases and 12.124 deaths [13]. It is indeed tragic that the COVID-19 pandemic has caused so much loss of life worldwide, including in the Republic of Moldova. The development of vaccines and antiviral drugs, as well as the use of human-neutralising antibodies (nAbs) are all essential strategies to combat the virus [14]. In March 2021, 2000 doses of Sinopharm vaccine were donated to the Republic of Moldova, which were administered exclusively to students and professors at the Nicolae Testemitanu University of Medicine and Pharmacy [15]. While vaccination campaigns are important in preventing the spread of COVID-19,effective therapeutic solutions are still needed [16] to treat people who have already been infected with the virus, especially those at higher risk of developing severe disease. Preliminary results from clinical trials have shown that the use of human neutralising antibodies targeting the ACE2 receptor binding domain (RBD) of SARS-CoV-2 can reduce disease severity and accelerate recovery in patients with COVID-19 [17,18]. Terapia cu plasmă convalescentă s-a dovedit a fi promițătoare în tratamentul pacienților cu COVID-19în stare critică [19]. The FDA has also recommended that convalescent plasma with a neutralising antibody titre greater than 1:160 be used for therapeutic transfusions [20]. However, theuseofconvalescent plasma is limited by the availability of donors with high levels of neutralising antibodies. Serological tests that detect neutralising antibodies to SARS-CoV-2 are essential for monitoring the effectiveness of vaccines and identifying people who may still be susceptible to the virus. Such tests can also be used to identify people who may have developed neutralising antibodies after being infected with SARS-CoV-2. [...