SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients.

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals.

SARS-CoV-2 recombinant proteins stimulate distinct cellular and humoral immune response profiles in samples from COVID-19 convalescent patients

OBJECTIVES: In this preliminary study we investigated cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in blood samples from 14 recovered coronavirus disease 2019 (COVID-19) patients and compared them to those in samples from 12 uninfected/unvaccinated volunteers. METHODS: Cellular immunity was assessed by intracellular detection of IFN-γ in CD3+ T lymphocytes after stimulation with SARS-CoV-2 spike (S1), nucleocapsid (NC), or receptor-binding domain (RBD) recombinant proteins or overlapping peptide pools covering the sequence of SARS-CoV-2 spike, membrane and nucleocapsid regions. The humoral response was examined by ELISAs and/or chemiluminescence assays for the presence of serum IgG antibodies directed to SARS-CoV-2 proteins. RESULTS: We observed differences between humoral and cellular immune profiles in response to stimulation with the same proteins. Assays of IgG antibodies directed to SARS-CoV-2 NC, RBD and S1/S2 recombinant proteins were able to differentiate convalescent from uninfected/unvaccinated groups. Cellular immune responses to SARS-CoV-2 protein stimuli did not exhibit a specific response, as T cells from both individuals with no history of contact with SARS-CoV-2 and from recovered donors were able to produce IFN-γ. CONCLUSIONS: Determination of the cellular immune response to stimulation with a pool of SARS-CoV-2 peptides but not with SARS-CoV-2 proteins is able to distinguish convalescent individuals from unexposed individuals. Regarding the humoral immune response, the screening for serum IgG antibodies directed to SARS-CoV-2 proteins has been shown to be specific for the response of recovered individuals.

Prevalence of anti-SARS-CoV-2 antibodies in outpatients of a large public university hospital in Sao Paulo, Brazil.

Coronavirus disease 19 (COVID-19) is caused by SARS-Cov-2 and the manifestations of this infection range from an absence of symptoms all the way up to severe disease leading to death. To estimate the prevalence of past infection in a population, the most readily available method is the detection of antibodies against the virus. This study has investigated the prevalence of anti-SARS-CoV-2 antibodies in outpatients of the Hospital das Clinicas, in Sao Paulo city (Brazil), which is a large university hospital belonging to the public health system that cares for patients with complex diseases who need tertiary or quaternary medical care. Our serological inquiry was carried out for 6 weeks, with once-a-week blood sampling and included 439 patients from several outpatient services. Overall, 61 patients tested positive for anti-SARS-CoV-2 IgG (13.9%); 56.1 % of the patients live in Sao Paulo city, with the remaining living in other towns of the metropolitan area; 32.8% of the patients testing positive for IgG antibodies to SARS-CoV-2 were asymptomatic, 55.7% developed mild or moderate disease and 11.5% had to be hospitalized. The prevalence of SARS-CoV-2 positive serology was lower among patients who had received the seasonal influenza vaccine compared to the ones who did not. These findings may indicate that those individuals care more about health issues, and/or that they have a better access to health care and/or a better quality of health care service. The large proportion of patients who were unaware of having had contact with SARS-CoV-2 deserves attention, reflecting the scarcity of tests performed in the population.

Autologous and allogenic systems of HIV expansion: what is the better choice for clinical application in therapeutic vaccine?

AIMS: HIV-1 expanded in an allogenic system (Al-HIV) represents a cheaper and faster alternative to the autologous virus (Au-HIV) as an antigen in anti-HIV immunotherapy. In this study, chemically inactivated HIV-1 obtained through autologous or allogenic systems were compared. PATIENTS & METHODS: Au-HIV and Al-HIV obtained from cultures of peripheral blood mononuclear cells from 11 HIV(+) individuals were tested for virus production, yield and time of culture, and their ability to elicit a specific immune response in vitro. RESULTS: The allogenic system was more efficient than the autologous system. Dendritic cells pulsed with Au-HIV and Al-HIV presented a similar phenotypic profile, but only Al-HIV induced a significant increase in IFN-γ(+) lymphocytes. CONCLUSION: The use of an allogenic system displays several advantages in terms of cell manipulation, time and cost of culture, and immunogenicity.

Efeito do congelamento na viabilidade e infectividade de ovos de Toxocara canis (PAP)

A toxocaríase é uma zoonose de incidência mundial causada por ascarídeos do gênero Toxocara. Considerando que a taxa de contaminação do solo por ovos de Toxocara canis é alta em várias regiões e que estudos apontam que ovos embrionados desse nematóide apresentam resistência elevada em condições ambientais hostis, este trabalho teve por objetivo estudar o impacto da diminuição da temperatura na viabilidade e infectividade de ovos de Toxocara canis. Suspensões de ovos embrionados de Toxocara canis foram mantidas sob temperatura média de - 15°C durante 1, 2, 5, 12, 20 e 30 dias, sendo que, uma suspensão controle permaneceu em estufa a 25°C. Ao final dos períodos de congelamento, amostras dos tubos foram examinadas ao microscópio para a observação da mobilidade larval. Posteriormente, os ovos foram testados quanto a sua infectividade em 29 camundongos BALB/c (4 animais por grupo, além do grupo sem congelamento com 5 camundongos), cada animal recebendo oralmente cerca de 300 ovos. Nos dias 30, 30 e 90 pós-infecção os camundongos de cada grupo foram sangrados, via plexo retro-orbitário, para pesquisa de anticorpos anti-Toxocara da classe IgG, empregando-se o teste imunoenzimático ELISA, onde foi possível observar que somente os grupos III, IV e VII foram reagentes para o antígeno ES de Toxocara canis, mas com baixos níveis de densidade óptica. Ao término dos 90 dias de infecção os animais foram sacrificados por deslocamento cervical e a análise microscópica indicou presença de larvas na carcaça, cérebro, fígado e olhos dos animais do grupo VII (sem congelamento) e grupo I, cujos ovos embrionados haviam sido submetidos à temperatura de -15ºC durante 24 horas. A reduzida quantidade de larvas encontradas nos tecidos e a baixa produção de anticorpos averiguada no teste ELISA indicam que a maioria dos ovos utilizados no experimento não estava infectante. Em conclusão, os efeitos adversos da exposição dos ovos de Toxocara canis a baixas temperaturas...