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This study monitored the long-term immune response to severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection in patients who had recovered from coronavirus disease (COVID)-19. Anti-nucleocapsid immunoglobulin G (anti-N IgG) titer in serum samples collected at a single (N = 302) or multiple time points (N = 229) 3–12 months after COVID-19 symptom onset or SARS-CoV-2 detection in respiratory specimens was measured by semiquantitative chemiluminescent microparticle immunoassay. The 531 patients (966 specimens) were classified according to the presence or absence of pneumonia symptoms. Anti N IgG was detected in 87.5% of patients (328/375) at 3 months, 38.6% (93/241) at 6 months, 23.7% (49/207) at 9 months, and 26.6% (38/143) at 12 months. The anti-N IgG seropositivity rate was significantly lower at 6, 9, and 12 months than at 3 months (P P P = 0.04), and 12 months (P = 0.04). The rate started to decline 6–12 months after symptom onset. Anti-N IgG sample/cutoff index was positively correlated with age (r = 0.192, P P

Understanding antibody responses after natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can guide the coronavirus disease 2019 (COVID-19) vaccine schedule, especially in resource-limited settings. This study aimed to assess the dynamics of SARS-CoV-2 antibodies, including anti-spike protein 1 (S1) immunoglobulin (Ig)G, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody against wild-type SARS-CoV-2 over time in a cohort of patients who were previously infected with the wild-type SARS-CoV-2. Between March and May 2020, 531 individuals with virologically confirmed cases of wild-type SARS-CoV-2 infection were enrolled in our immunological study. Blood samples were collected at 3-, 6-, 9-, and 12-months post symptom onset or detection of SARS-CoV-2 by RT-PCR (in asymptomatic individuals). The neutralizing titers against SARS-CoV-2 were detected in 95.2%, 86.7%, 85.0%, and 85.4% of recovered COVID-19 patients at 3, 6, 9, and 12 months after symptom onset, respectively. The seropositivity rate of anti-S1 IgG, anti-RBD total Ig, anti-S1 IgA, and neutralizing titers remained at 68.6%, 89.6%, 77.1%, and 85.4%, respectively, at 12 months after symptom onset. We observed a high level of correlation between neutralizing and SARS-CoV-2 spike protein-specific antibody titers. The half-life of neutralizing titers was estimated at 100.7 days (95% confidence interval = 44.5–327.4 days, R2 = 0.106). These results support that the decline in serum antibody levels over time in both participants with severe disease and mild disease were depended on the symptom severity, and the individuals with high IgG antibody titers experienced a significantly longer persistence of SARS-CoV-2-specific antibody responses than those with lower titers.

Understanding antibody responses after natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can guide the coronavirus disease 2019 (COVID-19) vaccine schedule. This study aimed to assess the dynamics of SARS-CoV-2 antibodies, including anti-spike protein 1 (S1) immunoglobulin (Ig)G, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody against wild-type SARS-CoV-2 in a cohort of patients who were previously infected with SARS-CoV-2. Between March and May 2020, 531 individuals with virologically confirmed cases of SARS-CoV-2 infection were enrolled in our immunological study. The neutralizing titers against SARS-CoV-2 were detected in 95.2%, 86.7%, 85.0%, and 85.4% of recovered COVID-19 patients at 3, 6, 9, and 12 months after symptom onset, respectively. The seropositivity rate of anti-S1 IgG, anti-RBD total Ig, anti-S1 IgA, and neutralizing titers remained at 68.6%, 89.6%, 77.1%, and 85.4%, respectively, at 12 months after symptom onset. The half-life of neutralizing titers was estimated at 100.7 days (95% confidence interval = 44.5 – 327.4 days, R2 = 0.106). These results support that the decline in serum antibody levels over time depends on the symptom severity, and the individuals with high IgG antibody titers experienced a significantly longer persistence of SARS-CoV-2-specific antibody responses than those with lower titers.

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 emerged in December 2019 and has spread globally. Although Thailand has been effective at controlling the spread of COVID-19, disease surveillance and information on antibody responses in infected cases and close contacts are needed because there is still no specific treatment or vaccine available. We investigated 217 recovered COVID-19 cases to monitor their viral RNA shedding and production of antibodies against SARS-CoV-2. The presence of antibodies in blood samples from 308 close contacts of COVID-19 cases was also determined. Viral RNA was still detectable in 6.6 % of recovered COVID-19 cases. The most prolonged duration of viral RNA shedding detected in this study was 105 days. IgM, IgG, and IgA antibodies against SARS-CoV-2 were detected in 13.82, 88.48, and 83.41 % of the recovered cases 4–12 weeks after disease onset, respectively. Although the patients had recovered from their illness, the levels of antibodies detected showed association with their symptoms during their stay in hospital. Fifteen of the 308 contacts (4.87 %) of COVID-19 cases tested positive for IgG antibodies. The presence of antibodies against SARS-CoV-2 suggested that there was viral exposure among close contacts. Viral clearance and the pattern of antibody responses in infected individuals are both crucial for effectively combatting SARS-CoV-2. Our study provides additional information on the natural history of this newly emerging disease related to both natural host defenses and a strategy for vaccine development.

Background and Aim Vitamin D insufficiency plays an important role in liver fibrosis in hepatitis C virus (HCV)-infected patients. We assessed liver fibrosis by transient elastography and 25 hydroxy vitamin D [25(OH)D] status in HCV-infected patients, with (HIV/HCV) or without HIV co-infection (HCV) from Thailand. Methods Fibrosis stage was defined as mild ( 14 kPa). Hypovitaminosis D was defined as 25(OH)D 1.45 (6.30, 2.70–14.74), P 1.45, and hypovitaminosis D are strong and independent predictors for the presence of advanced fibrosis in our HCV-infected patients. These data highlight the urgent need of HCV treatment and vitamin D supplement in resource-limited settings.

Vitamin D insufficiency plays an important role in liver fibrosis in hepatitis C virus (HCV)-infected patients. We assessed liver fibrosis by transient elastography and 25 hydroxy vitamin D [25(OH)D] status in HCV-infected patients, with (HIV/HCV) or without HIV co-infection (HCV) from Thailand.Fibrosis stage was defined as mild ( 7.1 kPa); moderate (7.2-9.4 kPa); severe (9.5-14 kPa), and cirrhosis ( 14 kPa). Hypovitaminosis D was defined as 25(OH)D 30 ng/mL. Logistic regression analyses were used to assess predictors for significant fibrosis. Serum 25(OH) D levels, HCV genotypes (GT), interleukin-28B (IL28B) and HCV-RNA were assessed.A total of 331 HCV and 130 HIV/HCV patients were enrolled (70% male, 35% people who inject drugs [PWIDs]). HCV GT distribution was as follows: GT3 47%, GT1 34%, GT6 17%. IL-28B CC genotype (rs12979860) were found in 88% of HIV/HCV and 85% of HCV. In HCV, liver fibrosis was mild in 56.5%; moderate in 18.4%; severe in 12.4%; and cirrhosis in 12.7%. In HIV/HCV, these figures were 30.6%, 27.8%, 17.6%, and 24.1%, respectively. Patients with significant fibrosis were more often male, older, with HIV infection, hypovitaminosis D, and less likely to be infected with GT6. Factors associated with significant fibrosis by multivariate analysis were HIV infection (adjusted odd ratio [95% confidential interval]: 2.67, 1.20-5.93), P = 0.016, Fib-4 score 1.45 (6.30, 2.70-14.74), P 0.001, and hypovitaminosis D (2.48, 1.09-5.67), P = 0.031. GT 6 was less likely to have advanced liver fibrosis (0.17, 0.05-0.65), P = 0.01.HIV infection, Fib-4 score 1.45, and hypovitaminosis D are strong and independent predictors for the presence of advanced fibrosis in our HCV-infected patients. These data highlight the urgent need of HCV treatment and vitamin D supplement in resource-limited settings.

Objectives:Cognitive impairment remains frequent in HIV, despite combination antiretroviral therapy (cART). Leading theories implicate peripheral monocyte HIV DNA reservoirs as a mechanism for spread of the virus to the brain. These reservoirs remain present despite cART. The objective of this study was to determine if the level of HIV DNA in CD14+ enriched monocytes predicted cognitive impairment and brain injury.Methods:We enrolled 61 cART-naïve HIV-infected Thais in a prospective study and measured HIV DNA in CD14+ enriched monocyte samples in a blinded fashion. We determined HAND diagnoses by consensus panel and all participants underwent magnetic resonance spectroscopy (MRS) to measure markers of brain injury. Immune activation was measured via cytokines in cerebrospinal fluid (CSF).Results:The mean (SD) age was 35 (6.9) years, CD4 T-lymphocyte count was 236 (139) and log10 plasma HIV RNA was 4.8 (0.73). Twenty-eight of 61 met HAND criteria. The log10 CD14+ HIV DNA was associated with HAND in unadjusted and adjusted models (p = 0.001). There was a 14.5 increased odds ratio for HAND per 1 log-value of HIV DNA (10-fold increase in copy number). Plasma CD14+ HIV DNA was associated with plasma and CSF neopterin (p = 0.023) and with MRS markers of neuronal injury (lower N-acetyl aspartate) and glial dysfunction (higher myoinositol) in multiple brain regions.Interpretation:Reservoir burden of HIV DNA in monocyte-enriched (CD14+) peripheral blood cells increases risk for HAND in treatment-naïve HIV+ subjects and is directly associated with CSF immune activation and both brain injury and glial dysfunction by MRS. © 2013 Valcour et al.