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1.
Front Cell Infect Microbiol ; 12: 882302, 2022.
Article in English | MEDLINE | ID: covidwho-1957150

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19), ranging from asymptomatic conditions to severe/fatal lung injury and multi-organ failure. Growing evidence shows that the nasopharyngeal microbiota composition may predict the severity of respiratory infections and may play a role in the protection from viral entry and the regulation of the immune response to the infection. In the present study, we have characterized the nasopharyngeal bacterial microbiota (BNM) composition and have performed factor analysis in a group of 54 asymptomatic/paucisymptomatic subjects who tested positive for nasopharyngeal swab SARS-CoV-2 RNA and/or showed anti-RBD-IgG positive serology at the enrolment. We investigated whether BNM was associated with SARS-CoV-2 RNA positivity and serum anti-RBD-IgG antibody development/maintenance 20-28 weeks after the enrolment. Shannon's entropy α-diversity index [odds ratio (OR) = 5.75, p = 0.0107] and the BNM Factor1 (OR = 2.64, p = 0.0370) were positively associated with serum anti-RBD-IgG antibody maintenance. The present results suggest that BNM composition may influence the immunological memory against SARS-CoV-2 infections. To the best of our knowledge, this is the first study investigating the link between BNM and specific IgG antibody maintenance. Further studies are needed to unveil the mechanisms through which the BNM influences the adaptive immune response against viral infections.


Subject(s)
COVID-19 , Microbiota , Antibodies, Viral , Humans , Immunoglobulin G , Nasopharynx , RNA, Viral/genetics , SARS-CoV-2
2.
Vaccines (Basel) ; 10(7)2022 Jul 17.
Article in English | MEDLINE | ID: covidwho-1939058

ABSTRACT

Background. The recent spread of the highly mutated SARS-CoV-2 Omicron variant (B.1.1.529) has raised concerns about protection against COVID-19 in congregate settings such as prisons, characterized by a high risk of transmission and possible difficulties in obtaining adequate vaccination coverage. The present study aims to investigate the spread of an outbreak of COVID-19 in an Italian correctional facility during the dominant circulation of the Omicron BA.1 variant, and also considers BNT162b2 mRNA vaccination coverage among inmates. A COVID-19 screening campaign by RT-PCR was performed on 515 detainees from 4-30 January 2022, in response to an outbreak that began in the correctional facility. Furthermore, 101 serum samples collected from healthy inmates 21 days after having received the second dose of the BNT162b2 vaccine were tested for neutralizing antibodies against both the wild-type SARS-CoV-2 strain and the Omicron BA.1 variant. The global attack rate during the study period was 43.6% (RR 0.8), progressively reducing from unvaccinated inmates (62.7%, RR 1.8) to those who had one dose (52.3%, RR 1.5), two doses (full cycle) (45.0%, RR 1.3), and the third dose (booster) vaccinated group (31.4%, RR 0.7). The percentage of SARS-CoV-2 positive subjects among unvaccinated inmates was significantly higher than in the other groups (p < 0.001), while no significant difference was observed between inmates with one or two vaccine doses. Only two of the positive inmates were hospitalized for COVID-19. The geometric mean titer of neutralizing antibodies in the tested sub-group after two doses of vaccine was lower than in previous studies against the wild-type virus, and showed a complete lack of neutralization against the Omicron variant in 92.1% of individuals. The findings support the need to prioritize vaccination in correctional facilities, as a public health measure to increase the protection of inmates and consequently of prison workers and the community against COVID-19, in coordination with the other prevention strategies.

3.
Vaccines (Basel) ; 10(5)2022 May 19.
Article in English | MEDLINE | ID: covidwho-1928676

ABSTRACT

BACKGROUND: Protozoa of the genus Leishmania are characterized by their capacity to target macrophages and Dendritic Cells (DCs). These microorganisms could thus be exploited for the delivery of antigens to immune cells. Leishmania tarentolae is regarded as a non-pathogenic species; it was previously used as a biofactory for protein production and has been considered as a candidate vaccine or as an antigen delivery platform. However, results on the type of immune polarization determined by L. tarentolae are still inconclusive. METHODS: DCs were derived from human monocytes and exposed to live L. tarentolae, using both the non-engineered P10 strain, and the same strain engineered for expression of the spike protein from SARS-CoV-2. We then determined: (i) parasite internalization in the DCs; and (ii) the capacity of the assayed strains to activate DCs and the type of immune polarization. RESULTS: Protozoan parasites from both strains were effectively engulfed by DCs, which displayed a full pattern of maturation, in terms of MHC class II and costimulatory molecule expression. In addition, after parasite infection, a limited release of Th1 cytokines was observed. CONCLUSIONS: Our results indicate that L. tarentolae could be used as a vehicle for antigen delivery to DCs and to induce the maturation of these cells. The limited cytokine release suggests L. tarentolae as a neutral vaccine vehicle that could be administered in association with appropriate immune-modulating molecules.

4.
Viruses ; 14(7)2022 06 30.
Article in English | MEDLINE | ID: covidwho-1917788

ABSTRACT

Italy was the second country affected by the SARS-CoV-2 pandemic; the virus spread mainly in Northern Italy with a subsequent diffusion to the center and southern part of the country. In this study, we aimed to assess the prevalence of antibodies against SARS-CoV-2 in the general population of the Siena province in the Tuscany region (Central Italy) during 2020. A total of 2480 serum samples collected from January to December 2020 were tested for IgM and IgG antibodies against SARS-CoV-2 by a commercial ELISA. Positive and borderline samples were further tested for the presence of anti-receptor-binding domain (RBD) IgM and IgG antibodies by an in-house ELISA and by a micro-neutralization assay. Out of the 2480 samples tested by the commercial ELISA, 81 (3.3%) were found to be positive or borderline for IgG and 58 (2.3%) for IgM in a total of 133 samples (5.4%) found to be positive or borderline for at least one antibody class. When the commercial ELISA and in-house ELISA/micro-neutralization assay results were combined, 26 samples (1.0%) were positive for RBD IgG, 11 (0.4%) for RBD IgM, and 23 (0.9%) for a neutralizing antibody. An increase in seroprevalence was observed during the year 2020, especially from the end of summer, consistent with the routine epidemiological surveillance of COVID-19 cases.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , COVID-19/epidemiology , Humans , Immunoglobulin G , Immunoglobulin M , Pandemics , Seroepidemiologic Studies
5.
Expert Rev Vaccines ; : 1-10, 2022 Jun 09.
Article in English | MEDLINE | ID: covidwho-1890645

ABSTRACT

INTRODUCTION: Influenza is a vaccine-preventable disease. Due to the evolving nature of influenza viruses, the composition of vaccines has to be updated annually. Most of the current influenza vaccines are still produced in embryonated chicken eggs, a well-established process with some limitations. AREA COVERED: This review focuses on the recombinant DNA technology using baculovirus expression vector system a modern method of manufacturing licensed influenza vaccines. The speed, scalability, biosafety and flexibility of the process, together with the reliability of the hemagglutinin in the vaccine, represent a significant advance toward new platforms for vaccine production. EXPERT OPINION: The scenario of vaccine production in the next years seems to be particularly interesting, involving a transition from the current egg-based production to new technologies, such as the cell culture platform, the RNA technology, the plant-based system, and the DNA vaccine. This latter offers great advantages over egg- and cell-based influenza vaccine production. The universal vaccine remains the goal of researchers and ideally would avoid the need for annual reformulation and re-administration of seasonal vaccines. The lesson learned from the COVID-19 pandemic highlights the importance of having different technologies available and able to promptly respond to a great demand of vaccines worldwide.

6.
Nat Commun ; 13(1): 3375, 2022 06 13.
Article in English | MEDLINE | ID: covidwho-1890184

ABSTRACT

SARS-CoV-2 vaccines, administered to billions of people worldwide, mitigate the effects of the COVID-19 pandemic, however little is known about the molecular basis of antibody cross-protection to emerging variants, such as Omicron BA.1, its sublineage BA.2, and other coronaviruses. To answer this question, 276 neutralizing monoclonal antibodies (nAbs), previously isolated from seronegative and seropositive donors vaccinated with BNT162b2 mRNA vaccine, were tested for neutralization against the Omicron BA.1 and BA.2 variants, and SARS-CoV-1 virus. Only 14.2, 19.9 and 4.0% of tested antibodies neutralize BA.1, BA.2, and SARS-CoV-1 respectively. These nAbs recognize mainly the SARS-CoV-2 receptor binding domain (RBD) and target Class 3 and Class 4 epitope regions on the SARS-CoV-2 spike protein. Interestingly, around 50% of BA.2 nAbs did not neutralize BA.1 and among these, several targeted the NTD. Cross-protective antibodies derive from a variety of germlines, the most frequents of which were the IGHV1-58;IGHJ3-1, IGHV2-5;IGHJ4-1 and IGHV1-69;IGHV4-1. Only 15.6, 20.3 and 7.8% of predominant gene-derived nAbs elicited against the original Wuhan virus cross-neutralize Omicron BA.1, BA.2 and SARS-CoV-1 respectively. Our data provide evidence, at molecular level, of the presence of cross-neutralizing antibodies induced by vaccination and map conserved epitopes on the S protein that can inform vaccine design.


Subject(s)
Antibodies, Neutralizing , COVID-19 , Antibodies, Viral , BNT162 Vaccine , COVID-19/prevention & control , COVID-19 Vaccines , Epitopes/genetics , Humans , Neutralization Tests , Pandemics/prevention & control , RNA, Messenger/genetics , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Vaccines, Synthetic , mRNA Vaccines
7.
Vaccines (Basel) ; 10(5)2022 May 01.
Article in English | MEDLINE | ID: covidwho-1875817

ABSTRACT

Influenza is a vaccine preventable disease and vaccination remains the most effective method of controlling the morbidity and mortality of seasonal influenza, especially with respect to risk groups. To date, three types of influenza vaccines have been licensed: inactivated, live-attenuated, and recombinant haemagglutinin vaccines. Effectiveness studies allow an assessment of the positive effects of influenza vaccines in the field. The effectiveness of current influenza is suboptimal, being estimated as 40% to 60% when the vaccines strains are antigenically well-matched with the circulating viruses. This review focuses on influenza viruses and vaccines and the role of vaccine effectiveness studies for evaluating the benefits of influenza vaccines. Overall, influenza vaccines are effective against morbidity and mortality in all age and risk groups, especially in young children and older adults. However, the effectiveness is dependent on several factors such as the age of vaccinees, the match between the strain included in the vaccine composition and the circulating virus, egg-adaptations occurring during the production process, and the subject's history of previous vaccination.

8.
Mol Ther ; 2022 May 10.
Article in English | MEDLINE | ID: covidwho-1860155

ABSTRACT

The COVID-19 pandemic continues to have devastating consequences on health and economy, even after the approval of safe and effective vaccines. Waning immunity, the emergence of variants of concern, breakthrough infections, and lack of global vaccine access and acceptance perpetuate the epidemic. Here, we demonstrate that a single injection of an adenoassociated virus (AAV)-based COVID-19 vaccine elicits at least 17-month-long neutralizing antibody responses in non-human primates at levels that were previously shown to protect from viral challenge. To improve the scalability of this durable vaccine candidate, we further optimized the vector design for greater potency at a reduced dose in mice and non-human primates. Finally, we show that the platform can be rapidly adapted to other variants of concern to robustly maintain immunogenicity and protect from challenge. In summary, we demonstrate this class of AAV can provide durable immunogenicity, provide protection at dose that is low and scalable, and be adapted readily to novel emerging vaccine antigens thus may provide a potent tool in the ongoing fight against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

9.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-336859

ABSTRACT

ABSTRACT The continuous evolution of SARS-CoV-2 generated highly mutated variants, like omicron BA.1 and BA.2, able to escape natural and vaccine-induced primary immunity 1,2 . The administration of a third dose of mRNA vaccines induces a secondary response with increased protection. We investigated, at single-cell level, the longitudinal evolution of the neutralizing antibody response in four donors after three mRNA doses 3 . A total of 4,100 spike protein specific memory B cells were single cell sorted and 350 neutralizing antibodies were identified. The third dose increased the antibody neutralization potency and breadth against all SARS-CoV-2 variants of concern as previously observed with hybrid immunity 3 . However, the B cell repertoire that stands behind the response is dramatically different. The increased neutralizing response was largely due to the expansion of B cell germlines poorly represented after two doses, and the reduction of germlines predominant after primary immunization such as IGHV3-53;IGHJ6-1 and IGHV3-66;IGHJ4-1. Divergently to hybrid immunity, cross-protection after a third dose was mainly guided by Class 1/2 antibodies encoded by IGHV1-58;IGHJ3-1 and IGHV1-69;IGHJ4-1 germlines. The IGHV2-5;IGHJ3-1 germline, which induced broadly cross-reactive Class 3 antibodies after infection or viral vector vaccination, was not induced by a third mRNA dose. Our data show that while neutralizing breadth and potency can be improved by different immunization regimens, each of them has a unique molecular signature which should be considered while designing novel vaccines and immunization strategies.

10.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-335709

ABSTRACT

Background: The recently emerged SARS-CoV-2 Omicron variant exhibits several mutations on the spike protein, enabling it to escape the immunity elicited by natural infection or vaccines. Avidity is the strength of binding between an antibody and its specific epitope. The SARS-CoV-2 spike protein binds to its cellular receptor with high affinity, and is the primary target of neutralizing antibodies. Therefore, protective antibodies should show high avidity. This study aimed at investigating the avidity of receptor-binding domain (RBD) binding antibodies and their neutralizing activity against the Omicron variant in COVID-19 patients and vaccinees. Methods: . Samples collected from COVID-19 patients and from subjects who received homologous or heterologous vaccination were tested for the avidity of RBD-binding IgG and neutralizing antibodies against the wild-type SARS-CoV-2 virus and the Omicron variant. Results: . In patients, RBD-binding IgG titres against the wild-type virus increased with time, but remained low. High neutralizing titres against the wild-type virus were not matched by high avidity or neutralizing activity against the Omicron variant. Vaccinees showed higher avidity than patients. Two vaccine doses elicited the production of neutralizing antibodies, but low avidity for the wild-type virus;antibody levels against the Omicron variant were even lower. Conversely, 3 doses of vaccine elicited high avidity and high neutralizing antibodies against both the wild-type virus and the Omicron variant. Conclusions: . Repeated vaccination increases antibody avidity against the spike protein of the Omicron variant, suggesting that antibodies with high avidity and high neutralizing potential increase cross-protection against variants that carry several mutations on the RBD.

11.
Molecular therapy : the journal of the American Society of Gene Therapy ; 2022.
Article in English | EuropePMC | ID: covidwho-1837975

ABSTRACT

The COVID19 pandemic continues to have devastating consequences on health and economy, even after the approval of safe and effective vaccines. Waning immunity, the emergence of variants of concern, breakthrough infections, and lack of global vaccine access and acceptance perpetuate the epidemic. Here, we demonstrate that a single injection of an AAV-based COVID19 vaccine elicits at least 17-month-long neutralizing antibody responses in non-human primates at levels that were previously shown to protect from viral challenge. To improve the scalability of this durable vaccine candidate, we further optimized the vector design for greater potency at a reduced dose in mice and nonhuman primates. Finally, we show that the platform can be rapidly adapted to other variants of concern to robustly maintain immunogenicity and protect from challenge. In summary, we demonstrate this class of AAV can provide durable immunogenicity, provide protection at dose that is low and scalable, and be adapted readily to novel emerging vaccine antigens thus may provide potent tool in the ongoing fight against SARS-CoV-2. Graphical This manuscript characterizes and optimizes an AAV-based vaccine platform for several COVID-19 development candidates: durability of humoral response at high level for over 20 months, the ability to reduce the dose and protect from challenge in NHP and the versatility and robustness of the platform across different variant of concern antigens.

12.
Nat Commun ; 13(1): 2263, 2022 04 27.
Article in English | MEDLINE | ID: covidwho-1815533

ABSTRACT

The emerging threat represented by SARS-CoV-2 variants, demands the development of therapies for better clinical management of COVID-19. MAD0004J08 is a potent Fc-engineered monoclonal antibody (mAb) able to neutralize in vitro all current SARS-CoV-2 variants of concern (VoCs) including the omicron variant even if with significantly reduced potency. Here we evaluated data obtained from the first 30 days of a phase 1 clinical study (EudraCT N.: 2020-005469-15 and ClinicalTrials.gov Identifier: NCT04932850). The primary endpoint evaluated the percentage of severe adverse events. Secondary endpoints evaluated pharmacokinetic and serum neutralization titers. A single dose administration of MAD0004J08 via intramuscular (i.m.) route is safe and well tolerated, resulting in rapid serum distribution and sera neutralizing titers higher than COVID-19 convalescent and vaccinated subjects. A single dose administration of MAD0004J08 is also sufficient to effectively neutralize major SARS-CoV-2 variants of concern (alpha, beta, gamma and delta). MAD0004J08 can be a major advancement in the prophylaxis and clinical management of COVID-19.


Subject(s)
Antibodies, Monoclonal , SARS-CoV-2 , Antibodies, Monoclonal/adverse effects , Antibodies, Monoclonal/blood , Antibodies, Viral , COVID-19 , Humans , Injections, Intramuscular , Neutralization Tests , SARS-CoV-2/immunology
13.
Front Public Health ; 10: 847384, 2022.
Article in English | MEDLINE | ID: covidwho-1792872

ABSTRACT

Background: Immunity and clinical protection induced by mRNA vaccines against SARS-CoV-2 have been shown to decline overtime. To gather information on the immunity profile deemed sufficient in protecting against hospitalization, we tested IgG levels, interferon-gamma (IFN-γ) secretion, and neutralizing antibodies 180 days (d180) after the second shot of BNT162b vaccine, in HW. Methods: A total of 392 subjects were enrolled. All received BioNTech/Pfizer from February 2020 to April 2021. The vaccine-specific humoral response was quantitatively determined by testing for IgG anti-S1 domain of SARS-CoV-spike protein. Live virus microneutralization (MN) was evaluated by an assay performing incubation of serial 2-fold dilution of human serum samples, starting from 1:10 to 1:5120, with an equal volume of Wuhan strain and Delta VOC viral solution and assessing the presence/absence of a cytopathic effect. SARS-CoV-2-spike protein-specific T-cell response was determined by a commercial IFN-γ release assay. Results: In 352 individuals, at d180, IgG levels decreased substantially but no results below the assay's positivity threshold were observed. Overall, 22 naive (8.1%) had values above the highest threshold. Among COVID-naive, the impact of age, which was observed at earlier stages, disappeared at d180, while it remained significant for 81 who had experienced a previous infection. Following the predictive model of protection by Khoury, we transformed the neutralizing titers in IU/ml and used a 54 IU/ml threshold to identify subjects with 50% protective immunity. Overall, live virus MN showed almost all subjects with previous exposure to SARS-CoV-2 neutralized the virus as compared to 33% of naive double-dosed subjects (p < 0.0001). All previously exposed subjects had strong IFN-γ secretion (>200 mIU/ml); among 271 naive, 7 (2.58%) and 17 (6.27%) subjects did not show borderline or strong secretion, respectively. Conclusions: In naive subjects, low IgG titers are relatively long-lasting. Only a third of naive subjects maintain neutralizing responses. After specific stimulation, a very limited number of naive were unable to produce IFN-γ. The results attained in the small group of subjects with breakthrough infection suggest that simultaneous neutralizing antibody titers <20, binding antibody levels/ml <200, and IFN-γ <1,000 mIU/ml in subjects older than 58 may identify at-risk groups.


Subject(s)
COVID-19 Vaccines , COVID-19 , Antibodies, Neutralizing/pharmacology , Antibodies, Viral , COVID-19/prevention & control , Health Personnel , Humans , Immunity, Humoral , Immunoglobulin G , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/pharmacology
14.
Oral Dis ; 2022 Apr 10.
Article in English | MEDLINE | ID: covidwho-1784721

ABSTRACT

OBJECTIVES: The objective of the study was to evaluate the in vitro virucidal activity of commercial mouthwashes against SARS-CoV-2 and variants of concern. MATERIALS AND METHODS: Antiviral activity was assessed at different time intervals, based on common use of these products by titrating residual viral infectivity on Vero E6 cells. RESULTS: All the mouthwashes were effective to reduce the infectious titers of SARS-CoV-2 and its tested variants. Mouthwashes Listerine® Cool Mint milder taste and Listerine® Cavity Protection milder taste reduced the infectious viral titer by up to 3.9 log10 after 30 s, while mouthwash Cetilsan® Sugar Free was able to reduce the viral titer by 2.2-2.9 log10 at all tested time intervals. Mouthwash Curasept® ADS DNA Intensive treatment was less effective to decrease viral infectivity (0.7-2.2 log10 TCID50/ml at all tested time intervals). Interestingly, the Gamma variant appeared more resistant to treatment in vitro with the different mouthwashes. CONCLUSIONS: In this study, we were able to assess the ability of different mouthwashes to in vitro decrease the infectivity of SARS-CoV-2 and its variants, and we observed that Gamma variant of concern was more resistant to treatment with mouthwashes.

15.
Allergy ; 77(8): 2446-2458, 2022 Aug.
Article in English | MEDLINE | ID: covidwho-1784580

ABSTRACT

BACKGROUND: The highly contagious SARS-CoV-2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS-CoV-2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of a vaccine against COVID-19. METHODS: In the current study, we evaluated the immunogenicity of a traditional vaccine platform based on virus-like particles (VLPs) displaying RBD of SARS-CoV-2 for intranasal administration in a murine model. The candidate vaccine platform, CuMVTT -RBD, has been optimized to incorporate a universal T helper cell epitope derived from tetanus-toxin and is self-adjuvanted with TLR7/8 ligands. RESULTS: CuMVTT -RBD vaccine elicited a strong systemic RBD- and spike-IgG and IgA antibodies of high avidity. Local immune response was assessed, and our results demonstrate a strong mucosal antibody and plasma cell production in lung tissue. Furthermore, the induced systemic antibodies could efficiently recognize and neutralize different variants of concern (VOCs). CONCLUSION: Our data demonstrate that intranasal administration of CuMVTT -RBD induces a protective systemic and local specific antibody response against SARS-CoV-2 and its VOCs.


Subject(s)
COVID-19 Vaccines , COVID-19 , Vaccines, Virus-Like Particle , Administration, Intranasal , Animals , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines/immunology , Humans , Mice , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Vaccines, Virus-Like Particle/immunology
16.
Hum Vaccin Immunother ; 18(5): 2047582, 2022 Nov 30.
Article in English | MEDLINE | ID: covidwho-1740707

ABSTRACT

In March 2020, the first pandemic caused by a coronavirus was declared by the World Health Organization. Italy was one of the first and most severely affected countries, particularly the northern part of the country. The latest evidence suggests that the virus could have been circulating, at least in Italy, before the first autochthonous SARS-COV-2 case was detected in February 2020. The present study aimed to investigate the presence of antibodies against SARS-CoV-2 in human serum samples collected in the last months of 2019 (September-December) in the Apulia region, Southern Italy. Eight of 455 samples tested proved positive on in-house receptor-binding-domain-based ELISA. Given the month of collection of the positive samples, these findings may indicate early circulation of SARS-CoV-2 in Apulia region in the autumn of 2019. However, it cannot be completely ruled out that the observed sero-reactivity could be an unknown antigen specificity in another virus to which subjects were exposed containing an epitope adventitiously cross-reactive with an epitope of SARS-CoV-2.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , COVID-19/epidemiology , Epitopes , Humans , Italy/epidemiology , Pandemics
17.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-328827

ABSTRACT

SARS-CoV-2 vaccines, administered to billions of people worldwide, are mitigating the effects of the COVID-19 pandemic, however little is known about the molecular basis of antibody cross-protection to emerging variants, such as Omicron (B.1.1.529), and other coronaviruses. To answer this question, 276 neutralizing monoclonal antibodies (nAbs), previously isolated from seronegative and seropositive donors vaccinated with BNT162b2 mRNA vaccine1, were tested for neutralization against the Omicron variant and SARS-CoV-1 virus. Cross-neutralizing antibodies were isolated from 100% of seropositive and 20% of seronegative vaccinees. Only 14.2% and 4.0% of tested antibodies neutralized the Omicron variant and SARS-CoV-1 respectively. These nAbs recognized mainly the SARS-CoV-2 receptor binding domain (RBD) and targeted class 3 and class 4 epitope regions on the SARS-CoV-2 spike protein. Antibodies targeting class 1/2 epitope regions only rarely showed cross-neutralization activity. Cross-protective antibodies derived from a variety of germlines, the most frequents of which were the IGHV1-58;IGHJ3-1 and IGHV1-69;IGHV4-1. Only 15.6% and 7.8% of predominant gene-derived nAbs elicited against the original Wuhan virus cross-neutralized Omicron and SARS-CoV-1 respectively. Our data provide evidence of the presence of cross-neutralizing antibodies induced by vaccination and map conserved epitopes on the S protein that can inform vaccine design.

18.
Viruses ; 14(1)2021 12 30.
Article in English | MEDLINE | ID: covidwho-1580400

ABSTRACT

The massive emergence of COVID-19 cases in the first phase of pandemic within an extremely short period of time suggest that an undetected earlier circulation of SARS-CoV-2 might have occurred. Given the importance of this evidence, an independent evaluation was recommended by the World Health Organization (WHO) to test a subset of samples selected on the level of positivity in ELISA assays (positive, low positive, negative) detected in our previous study of prepandemic samples collected in Italy. SARS-CoV-2 antibodies were blindly retested by two independent centers in 29 blood samples collected in the prepandemic period in Italy, 29 samples collected one year before and 11 COVID-19 control samples. The methodologies used included IgG-RBD/IgM-RBD ELISA assays, a qualitative micro-neutralization CPE-based assay, a multiplex IgG protein array, an ELISA IgM kit (Wantai), and a plaque-reduction neutralization test. The results suggest the presence of SARS-CoV-2 antibodies in some samples collected in the prepandemic period, with the oldest samples found to be positive for IgM by both laboratories collected on 10 October 2019 (Lombardy), 11 November 2019 (Lombardy) and 5 February 2020 (Lazio), the latter with neutralizing antibodies. The detection of IgM and/or IgG binding and neutralizing antibodies was strongly dependent on the different serological assays and thresholds employed, and they were not detected in control samples collected one year before. These findings, although gathered in a small and selected set of samples, highlight the importance of harmonizing serological assays for testing the spread of the SARS-CoV-2 virus and may contribute to a better understanding of future virus dynamics.


Subject(s)
COVID-19/epidemiology , SARS-CoV-2/isolation & purification , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Asymptomatic Infections/epidemiology , COVID-19/diagnosis , COVID-19 Serological Testing/standards , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Italy/epidemiology , SARS-CoV-2/immunology , Time Factors
19.
Front Microbiol ; 12: 736530, 2021.
Article in English | MEDLINE | ID: covidwho-1581277

ABSTRACT

To detect and prevent emerging epidemics, discovery platforms are urgently needed, for the rapid development of diagnostic assays. Molecular diagnostic tests for COVID-19 were developed shortly after the isolation of SARS-CoV-2. However, serological tests based on antiviral antibody detection, revealing previous exposure to the virus, required longer testing phases, due to the need to obtain correctly folded and glycosylated antigens. The delay between the identification of a new virus and the development of reliable serodiagnostic tools limits our readiness to tackle future epidemics. We suggest that the protozoan Leishmania tarentolae can be used as an easy-to-handle microfactory for the rapid production of viral antigens to face emerging epidemics. We engineered L. tarentolae to express the SARS-CoV-2 receptor-binding domain (RBD) and we recorded the ability of the purified RBD antigen to detect SARS-CoV-2 infection in human sera, with a sensitivity and reproducibility comparable to that of a reference antigen produced in human cells. This is the first application of an antigen produced in L. tarentolae for the serodiagnosis of a Coronaviridae infection. On the basis of our results, we propose L. tarentolae as an effective system for viral antigen production, even in countries that lack high-technology cell factories.

20.
Clin Chem Lab Med ; 59(8): 1463-1467, 2021 07 27.
Article in English | MEDLINE | ID: covidwho-1546996

ABSTRACT

OBJECTIVES: COVID-19 has brought about tests from many manufacturers. While molecular and rapid antigen tests are targeted for early diagnosis, immunoassays have a larger role in epidemiological studies, understanding longitudinal immunity, and in vaccine development and response. METHODS: The performance of the LIAISON® SARS-CoV-2 TrimericS IgG assay was evaluated against the Beckman ACCESS SARS-CoV-2 IgG assay in New Mexico, and against the Siemens ADVIA Centaur COV2G assay in New York. Discordant samples were parsed using a microneutralization assay. RESULTS: A SARS-CoV-2 antibody positivity rate of 23.8% was observed in the samples tested in New York (September 2020), while in the same month the positivity rate was 1.5% in New Mexico. Positive and negative agreement were 67.6% (95% CI 49.5-82.6%) and 99.8% (95% CI 99.5-99.9%), respectively, with the Beckman test, and 98.0% (95% CI 95.7-99.3%) and 94.8% (95% CI 93.4-96.0%), respectively, with the Siemens test. Receiver operating characteristic analysis for the detection of SARS-CoV-2 antibodies discloses an AUC, area under the curve, of 0.996 (95% CI 0.992-0.999) for the LIAISON® SARS-CoV-2 TrimericS IgG assay. The criterion associated to the Youden Index was determined to be >12.9 kAU/L with a sensitivity of 99.44% and a specificity of 99.82%. CONCLUSIONS: The LIAISON® SARS-CoV-2 TrimericS IgG assay is highly sensitive and specific. The balance of these parameters, without emphasis on high specificity alone, is particularly important when applied to high prevalence populations, where a highly sensitive assay will result in reporting a lower number of false negative subjects.


Subject(s)
Antibodies, Viral/blood , COVID-19/diagnosis , Immunoassay/methods , Immunoglobulin G/blood , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/immunology , Area Under Curve , Automation , COVID-19/virology , Humans , ROC Curve , Reagent Kits, Diagnostic , SARS-CoV-2/isolation & purification , Sensitivity and Specificity
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