Hindawi Journal of Immunology Research Volume 2022, Article ID 8287087, 4 pages https://doi.org/10.1155/2022/8287087 Research Article SARS-CoV-2 Spike Protein Vaccine-Induced Immune Imprinting Reduces Nucleocapsid Protein Antibody Response in SARS-CoV- 2 Infection Juan F. Delgado ,1 Mónica Vidal-Pla,1 M. Carmen Moya,2 Mateu Espasa,3 Antonio Casabella,3 Manel Seda,2 Joan Calvet,4 Jordi Gratacós,4 Rosa M. Serrano,2 and Pilar Peña2 1 Immunology Unit, Laboratory Service, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Departament de Medicina, Sabadell, Spain 2 Occupational Health Department, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Sabadell, Spain 3 Microbiology Unit, Laboratory Service, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Sabadell, Spain 4 Rheumatology Service, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Departament de Medicina, Sabadell, Spain Correspondence should be addressed to Juan F. Delgado; jdelgado@tauli.cat Received 27 May 2022; Accepted 8 July 2022; Published 29 July 2022 Academic Editor: Baohui Xu Copyright © 2022 Juan F. Delgado et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Immune imprinting or original antigenic sin (OAS) is the process by which the humoral memory response to an antigen can inhibit the response to new epitopes of that antigen originating from a second encounter with the pathogen. Given the situation of the COVID-19 pandemic, multiple vaccines have been developed against SARS-CoV-2 infection. These vaccines are directed to the spike protein (S protein) of the original variant of Wuhan D614G. Vaccine memory immune response against S protein in noninfected subjects could inhibit, through the OAS mechanism, the response to new epitopes of SARS- CoV-2 after infection. The present study analyzes whether the memory antibody B cell response generated by mRNA vaccines against S protein can inhibit the primary antibody immune response to other SARS-CoV-2 antigens, such as nucleocapsid protein (N protein). SARS-CoV-2 primary infection in vaccinated healthcare workers (HCWs) produced significantly lower titers of anti-N antibodies than that in nonvaccinated HCWs: 5.7 (IQR 2.3-15.2) versus 12.2 (IQR 4.2-32.0), respectively (p = 0:005). Therefore, spike protein vaccine-induced immune imprinting (original antigenic sin) reduces N protein antibody response. 1. Introduction ing to OAS, when a virus infects an organism, the individual develops a primary immune response to virus antigens that Immune imprinting or original antigenic sin (OAS) refers to activates innate and adaptive immunity leading to the pro- the immune system’s preference to activate existing memory duction of memory T and B cells. In a second entry of the cells when an individual encounters a new but closely related same virus, the organism develops a secondary immune antigen rather than stimulating de novo responses to the response that is of great intensity and affinity and faster than new epitopes. This mechanism has been reported in mRNA the primary response. This secondary response can even viruses, such as influenza, dengue, and HIV [1, 2]. Accord- inhibit a primary response against new epitope antigens if 2 Journal of Immunology Research the virus partially modifies its antigen [1–4]. The goal of vac- 3. Discussion cination is to develop a strong and efficient response from T and B cells that leads to a mild infection. A problem arises OAS is the process by which the humoral memory response when the pathogen acquires the ability to slightly change to an antigen can inhibit the response to new epitopes of that its antigens, and due to the OAS mechanism, it could inhibit antigen originating from a second encounter with the path- the primary response against new antigens, reducing the ogen [7]. mRNA vaccines are administered intramuscularly, immune system’s ability to neutralize the pathogen and, and the mRNA encoding for protein S enters into different therefore, leading to more severe disease [1–4]. cells, including antigen-presenting cells. These cells circulate Given the situation of the COVID-19 pandemic, multi- to the lymph node and present S protein epitopes to cyto- ple vaccines have been developed against SARS-CoV-2 toxic T cells and helper T cells (Th). A subset of Th cells that infection. The first vaccines approved by the American and recognize S protein epitopes will differentiate into follicular European drug agencies have been the mRNA vaccines. Th cells (Thf) that will traffic to the germinal center. These These vaccines are directed to the spike protein (S protein) Thf cells participate in the activation of naive B cells that rec- of the original variant of Wuhan D614G [5, 6]. In the evolu- ognize these S protein epitopes at first and then induce tion of the pandemic, new variants with mutations in the S mechanisms of affinity maturation and memory generation protein have emerged. These mutations in the S protein [8]. Therefore, mRNA vaccination induces a B cell memory could induce an OAS process in which the memory response response [9]. mRNA vaccines effectively prevent severe against conserved areas of the S protein inhibits the response disease, but they do not prevent infection; consequently, vac- to new epitopes generated by these mutations [1–6]. cinated individuals could be infected by SARS-CoV-2 [10]. The present study analyzes whether the memory anti- In this context, SARS-CoV-2 initiates the immune response body B cell response generated by mRNA vaccines against in which there are already memory B cells that recognize S protein can inhibit the primary antibody immune response epitopes of the S protein. Therefore, common epitopes to other SARS-CoV-2 antigens, such as nucleocapsid protein among SARS-CoV-2 variants, new epitopes generated by (N protein). Therefore, antibody response against N protein the variants, and epitopes from other SARS-CoV-2 proteins in both healthcare workers (HCWs) infected by SARS-CoV- will be presented in the lymph node. Regarding the common 2 after vaccination and nonvaccinated HCWs was analyzed epitopes, a rapid and intense memory response will be initi- and compared. ated, and in our study, we have shown how the antibody titers against S protein after the infection were >34 times higher than the previous titers presented by the HCWs 2. Results (Table 1). For new epitopes or epitopes from other SARS- CoV-2 proteins, a primary immune response will be devel- The demographic and analytical characteristics of the HCWs oped. Our study analyzed the primary response against N included in the study were similar between vaccinated and protein, and we have shown that vaccinated HCWs (S nonvaccinated groups, except for antibody titers against N protein memory response) developed an antibody response protein after infection (Table 1). All HCWs in the vaccinated less than half of what nonvaccinated HCWs developed group after infection have increased antibody titers against S (Table 1). Further studies analyzing the antibody response protein (>34 fold change, p < 0:001). The real magnitude of against new S protein epitopes from SARS-CoV-2 variants this increase cannot be appreciated since there is an upper in homogeneous groups of vaccinated and nonvaccinated limit of 25,000 BAU/mL due to the maximum automatic primary infected patients are needed to elucidate whether sample dilution by the Cobas e 801 analyzer. This S protein the reduced response observed against N protein could also antibody response we observed was mainly due to the mem- occur for S protein and the magnitude of this effect, in which ory antibody response induced by vaccination. Subsequently, in the case of anti-N protein antibodies, our study showed a we have analyzed the N protein antibody response in HCWs reduction of 53.3% of the median response. This phenome- from the vaccinated group and from the nonvaccinated non should be taken into account in the development of group to evaluate the influence of the S protein memory anti- vaccines against these new variants. body response in another SARS-CoV-2 antigen. To evaluate In response to human coronaviruses, neutralizing anti- this response, we have analyzed the different registered vari- bodies typically bind to the S protein and disrupt viral entry ables shown in Table 1 as possible confounding factors, by blocking interactions between viruses and ACE2 host studying the influence of each of these variables using linear receptors [11]. However, N proteins from different viruses regression models. Coefficient variation applying the vari- used as vaccines can protect the hosts against the virus infec- ables changes by less than 5%, given the homogeneous distri- tions [11]. Severe infection was associated with enhanced bution of the different variables in both groups (Table 1). anti-S and anti-N protein antibody responses, and high Therefore, S protein vaccine-induced immune imprinting is anti-N protein titers were especially observed in patients an independent variable when analyzing its effect on the anti- who suffered long hospitalizations. [12]. Although the body response to N protein. N protein response is greater in response against the N protein is important for the protec- the HCWs from the nonvaccinated group compared to the tion against SARS-CoV-2 infection, the inhibition observed vaccinated group: 12.2 (IQR 4.2-32.0) versus 5.7 (IQR 2.3- in our research in HCWs who have developed a memory 15.2), respectively. This 2.1 fold change between groups was response against the S protein, induced by the vaccine, prob- statistically significant (p = 0:005) (Table 1). ably does not have a significant effect on protection against Journal of Immunology Research 3 Table 1: Demographic and analytical characteristics of HCWs included in the study. HCWs vaccinated (n = 55) HCW nonvaccinated (n = 188) p value Sex (women) 80.4% 75.0% 0.423 Age (years) 40:9 ± 11:5 41:3 ± 12:7 0.809 Time interval infection to serology (days) 22.0 (IQR 14.0-45.0) 18.0 (IQR 11.0-34.0) 0.379 S protein antibodies before infection (BAU/mL) 703.0 (IQR 383.0-1362.0) N.D. — N protein antibodies before infection (index) 0.09 (IQR 0.09-0.10) 0.09 (IQR 0.08-0.10) 0.953 S protein antibodies after infection (BAU/mL) 24,062.0 (IQR 11,753.0-25,000.0) N.D. — N protein antibodies after infection (index) 5.7 (IQR 2.3-15.2) 12.2 (IQR 4.2-32.0) 0.005 Categorical variables are expressed in frequencies, and continuous variables are expressed in median and interquartile range for nonparametrical variables and in mean and standard deviation for parametrical variables. p values were obtained using the chi-square test for categorical variables and the Mann-Whitney U test (nonparametrical) or Student’s t-test (parametrical) for continuous quantitative variables. HCWs: healthcare workers; IQR: interquartile range; S protein: spike protein; N protein: nucleocapsid protein BAU: binding antibody units; N.D.: not determined. infection due to the great efficacy of the S protein memory Lack of response to the N protein was defined at anti-N pro- response against SARS-CoV-2 [13]. tein antibody titers lower than one. The titers of anti-S pro- Our study has limitations. The group of HCWs vacci- tein antibodies have an upper limit of 25,000 BAU/mL since nated with primary infection is low (n = 55), but it is enough the last dilution performed in the routine analysis is 1/100; to achieve statistical significance. The study population was samples with titers higher than 25,000 BAU/mL have been HCW; therefore, our cohort is heterogeneous from a socio- assigned 25,000 BAU/mL. economic point of view and is representative of the general population restricted to healthy individuals, aged from 18 4.3. Statistical Analysis. For descriptive purposes, the cohort to 65. The antibody titers against N protein developed by was characterized using absolute and relative frequencies for primary infected HCWs could be underestimated since the categorical variables, while medians were used for numerical commercial immunoassay detects antibodies against the measures. We tested the association between variables with original N protein and not the variant N protein. In addi- the chi-square for categorical variables and the Mann- tion, this commercial immunoassay was semiquantitative Whitney U test or Student’s t-test for continuous quantita- (index). tive variables. The quantitative differences in anti-protein In conclusion, our results showed that the vaccine- N antibodies between groups were evaluated using linear induced immune imprinting against the S protein partially regression models, analyzing the coefficient variation after inhibits the response against the N protein after SARS- introducing the different variables in these models. The var- CoV-2 infection. iation of the coefficient was <5%. Therefore, a univariate analysis was applied using the Mann-Whitney U test, given the nonparametric nature of the antibody response against 4. Methods N protein. 4.1. Patients. Two hundred thirty-nine HCWs who had a pri- mary infection by SARS-CoV-2 with a PCR positive test were Data Availability included. Among these subjects, 51 HCWs were vaccinated The data that support the findings of this study are available with mRNA vaccines against S protein (44 with BTN162b2 from the corresponding author upon reasonable request. and 7 with mRNA-1273) and 188 were nonvaccinated. In the vaccinated group, antibodies against S protein were determined 123 ± 20 days after the second dose of mRNA Ethical Approval vaccine, and all primary infections occurred after vaccina- The study was conducted in compliance with data protec- tion. Age, sex, antibodies against S and N proteins before tion regulations and with Biomedical Research Law in Spain. and after infection, the time interval between infection, The study was approved by the Drug Research Ethics Com- and/or vaccination and serology were collected from the mittee of Parc Taulí University Hospital, Sabadell, under ref- medical history database (Table 1). The study was approved erence 2021/5112. by the Drug Research Ethics Committee of Parc Taulí Uni- versity Hospital, Sabadell, under reference 2021/5112. Conflicts of Interest 4.2. Detection of SARS-CoV-2 Antibodies. Antibody response The authors declare that they have no conflicts of interest. to SARS-CoV-2 S protein was measured using the Elecsys® Anti-SARS-CoV-2 S test (quantitative), while antibody Authors’ Contributions response to SARS-CoV-2 N protein was measured using the Elecsys® Anti-SARS-CoV-2 IgM/IgA/IgG test (Roche Juan F. Delgado was responsible for the study design, sample Diagnostics International Ltd., Rotkreuz, Switzerland, semi- processing, collection of analytical data, result analysis, quantitative) according to the manufacturer’s instructions. drafting of the manuscript, and statistical analysis. Mónica 4 Journal of Immunology Research Vidal was responsible for the sample processing, collection [11] D. J. Gregory, A. Vannier, A. H. Duey et al., “Repertoires of of analytical data, result analysis, and statistical analysis. M SARS-CoV-2 epitopes targeted by antibodies vary according Carmen Moya was responsible for the collection of clinical to severity of COVID-19,” Virulence, vol. 13, no. 1, pp. 890– data. Mateu Espasa and Antonio Casabella were responsible 902, 2022. for the HCW stratification. Manuel Seda was responsible for [12] J. J. Guthmiller, O. Stovicek, J. Wang et al., “SARS-CoV-2 the collection of clinical data. Joan Calvet was responsible infection severity is linked to superior humoral immunity for the result analysis. Jordi Gratacós was responsible for against the spike,” MBio, vol. 12, no. 1, 2021. the result analysis and critical revision of the manuscript. [13] M. A. Sughayer, L. Souan, M. M. 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