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1.
Front Immunol ; 13: 817905, 2022.
Article in English | MEDLINE | ID: covidwho-1699973

ABSTRACT

The duration of humoral and cellular immune memory following SARS-CoV-2 infection in populations in least developed countries remains understudied but is key to overcome the current SARS-CoV-2 pandemic. Sixty-four Cambodian individuals with laboratory-confirmed infection with asymptomatic or mild/moderate clinical presentation were evaluated for Spike (S)-binding and neutralizing antibodies and antibody effector functions during acute phase of infection and at 6-9 months follow-up. Antigen-specific B cells, CD4+ and CD8+ T cells were characterized, and T cells were interrogated for functionality at late convalescence. Anti-S antibody titers decreased over time, but effector functions mediated by S-specific antibodies remained stable. S- and nucleocapsid (N)-specific B cells could be detected in late convalescence in the activated memory B cell compartment and are mostly IgG+. CD4+ and CD8+ T cell immune memory was maintained to S and membrane (M) protein. Asymptomatic infection resulted in decreased antibody-dependent cellular cytotoxicity (ADCC) and frequency of SARS-CoV-2-specific CD4+ T cells at late convalescence. Whereas anti-S antibodies correlated with S-specific B cells, there was no correlation between T cell response and humoral immune memory. Hence, all aspects of a protective immune response are maintained up to nine months after SARS-CoV-2 infection and in the absence of re-infection.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Immunologic Memory/immunology , SARS-CoV-2/immunology , B-Lymphocytes/immunology , COVID-19/pathology , Cambodia , Coronavirus Nucleocapsid Proteins/immunology , Humans , Immunity, Cellular/immunology , Immunity, Humoral/immunology , Phosphoproteins/immunology , Spike Glycoprotein, Coronavirus/immunology
2.
J Infect Dis ; 224(9): 1489-1499, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1522216

ABSTRACT

BACKGROUND: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a complex antibody response that varies by orders of magnitude between individuals and over time. METHODS: We developed a multiplex serological test for measuring antibodies to 5 SARS-CoV-2 antigens and the spike proteins of seasonal coronaviruses. We measured antibody responses in cohorts of hospitalized patients and healthcare workers followed for up to 11 months after symptoms. A mathematical model of antibody kinetics was used to quantify the duration of antibody responses. Antibody response data were used to train algorithms for estimating time since infection. RESULTS: One year after symptoms, we estimate that 36% (95% range, 11%-94%) of anti-Spike immunoglobulin G (IgG) remains, 31% (95% range, 9%-89%) anti-RBD IgG remains, and 7% (1%-31%) of anti-nucleocapsid IgG remains. The multiplex assay classified previous infections into time intervals of 0-3 months, 3-6 months, and 6-12 months. This method was validated using data from a seroprevalence survey in France, demonstrating that historical SARS-CoV-2 transmission can be reconstructed using samples from a single survey. CONCLUSIONS: In addition to diagnosing previous SARS-CoV-2 infection, multiplex serological assays can estimate the time since infection, which can be used to reconstruct past epidemics.


Subject(s)
Antibodies, Viral/blood , COVID-19/blood , COVID-19/immunology , Serologic Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , Antibody Formation , Antibody Specificity , COVID-19/epidemiology , Female , France/epidemiology , Humans , Immunoglobulin G/blood , Kinetics , Male , Middle Aged , SARS-CoV-2/immunology , Sensitivity and Specificity , Seroepidemiologic Studies , Young Adult
3.
J Infect Dis ; 224(9): 1489-1499, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1317919

ABSTRACT

BACKGROUND: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a complex antibody response that varies by orders of magnitude between individuals and over time. METHODS: We developed a multiplex serological test for measuring antibodies to 5 SARS-CoV-2 antigens and the spike proteins of seasonal coronaviruses. We measured antibody responses in cohorts of hospitalized patients and healthcare workers followed for up to 11 months after symptoms. A mathematical model of antibody kinetics was used to quantify the duration of antibody responses. Antibody response data were used to train algorithms for estimating time since infection. RESULTS: One year after symptoms, we estimate that 36% (95% range, 11%-94%) of anti-Spike immunoglobulin G (IgG) remains, 31% (95% range, 9%-89%) anti-RBD IgG remains, and 7% (1%-31%) of anti-nucleocapsid IgG remains. The multiplex assay classified previous infections into time intervals of 0-3 months, 3-6 months, and 6-12 months. This method was validated using data from a seroprevalence survey in France, demonstrating that historical SARS-CoV-2 transmission can be reconstructed using samples from a single survey. CONCLUSIONS: In addition to diagnosing previous SARS-CoV-2 infection, multiplex serological assays can estimate the time since infection, which can be used to reconstruct past epidemics.


Subject(s)
Antibodies, Viral/blood , COVID-19/blood , COVID-19/immunology , Serologic Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , Antibody Formation , Antibody Specificity , COVID-19/epidemiology , Female , France/epidemiology , Humans , Immunoglobulin G/blood , Kinetics , Male , Middle Aged , SARS-CoV-2/immunology , Sensitivity and Specificity , Seroepidemiologic Studies , Young Adult
4.
J Gen Virol ; 102(3)2021 03.
Article in English | MEDLINE | ID: covidwho-1015423

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), presents a challenge to laboratorians and healthcare workers around the world. Handling of biological samples from individuals infected with the SARS-CoV-2 virus requires strict biosafety measures. Within the laboratory, non-propagative work with samples containing the virus requires, at minimum, Biosafety Level-2 (BSL-2) techniques and facilities. Therefore, handling of SARS-CoV-2 samples remains a major concern in areas and conditions where biosafety for specimen handling is difficult to maintain, such as in rural laboratories or austere field testing sites. Inactivation through physical or chemical means can reduce the risk of handling live virus and increase testing ability especially in low-resource settings due to easier and faster sample processing. Herein we assess several chemical and physical inactivation techniques employed against SARS-CoV-2 isolates from Cambodia. This data demonstrates that all chemical (AVL, inactivating sample buffer and formaldehyde) and heat-treatment (56 and 98 °C) methods tested completely inactivated viral loads of up to 5 log10.


Subject(s)
COVID-19/virology , Containment of Biohazards , SARS-CoV-2 , Specimen Handling , Virus Inactivation , Animals , Cambodia , Cells, Cultured , Chlorocebus aethiops , Hot Temperature , Humans , SARS-CoV-2/drug effects , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Viral Load/drug effects , Viral Load/statistics & numerical data , Virus Inactivation/drug effects
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