A possible dose-response equation: Viral load after plasma infusion in COVID-19 patients and anti-SARS-CoV-2 antibody titers in convalescent plasma.

BACKGROUND: Clinical trials of convalescent plasma therapy for coronavirus disease 2019 (COVID-19) are extensive, but the relationship between antibody titers, infused volume of plasma and virus clearance in patients remains unknown. This study proposed a possible estimating equation for clinical use of high antibody titer convalescent plasma. METHODS: A total of 38 patients were recruited in the Guanggu District Maternal and Child Health Hospital of Hubei Province from March 1 to 30, 2020. COVID-19 convalescent plasma was collected and high-titer (≥1:640) anti-S-RBD units used. The SARS-CoV-2 nucleic acid viral load was measured 24 h before and 72 h after convalescent plasma infusion. RESULTS: Convalescent plasma therapy was associated with reduced viral load in patients with moderate and severe severity. The viral negative rate at 72 h was 65.8%. The disappearance of viral nucleic acid in study patients was positively correlated with infuscate antibody titer and volume (r = 0.3375, p = 0.04). A possible estimation equation was as follows: Log10 (Reduction in viral load) = 0.18 + 0.001 × (Log2 S-RBD antibody titer × Plasma infusion volume) (r = 0.424, p = 0.009). In a single case, the viral nucleic acid persisted 14 days after the fourth plasma infusion. CONCLUSIONS: This study proposes a potential dose-response equation that adds a convenient way to estimate the dose of convalescent plasma product. It is beneficial to facilitate the rational allocation of plasma with high antibody titers and provide an individualised use strategy for convalescent plasma therapy.

Epidemiological survey and screening strategy for dengue virus in blood donors from Yunnan Province.

BACKGROUND: Dengue virus (DENV) infection is increasingly common in southern China and can be transmitted through blood transfusion but is not currently part of donor screening throughout the region. We assessed DENV prevalence among donors at the Xishuangbanna Blood Center, Yunnan, to support development of DENV screening strategies. METHODS: Blood samples were collected randomly between June 2019 and August 2019. These were screened for anti-DENV IgG and IgM using enzyme-linked immunosorbent assay (ELISA). Then, all reactive samples and some randomly-chosen non-reactive samples were used to detect DENV RNAs using real-time polymerase-chain-reaction (RT-PCR) assays. After RT-PCR, samples were further tested for soluble nonstructural protein 1 (NS1) using the colloidal gold method. Donors demographics were also collected and assessed. RESULTS: Over the study period, 2254 donor samples were collected and tested for anti-DENV IgG and IgM by ELISA. This revealed 598 anti-DENV IgG and/or IgM reactive samples, a serological prevalence of 26.53%. Of these, 26 were RT-PCR positive and/or NS1 positive. Significant differences in DENV prevalence were noted by occupation (P = 0.001), education (P < 0.001), and ethnicity (P = 0.026). CONCLUSION: The prevalence of DENV in Xishuangbanna Blood Center was higher than most other blood centers that have implemented DENV donor screening. Our study provides first-hand data about the prevalence of DENV and allows the development of a screening strategy for clinical use.

Effects of riboflavin and ultraviolet light treatment on pathogen reduction and platelets.

BACKGROUND: Pathogen reduction technology has become an accepted method for limiting transfusion-transmitted infections (TTIs). Riboflavin and ultraviolet light (RUV) treatment of platelets (PLTs) is an optional means of pathogen inactivation owing to its safety, effectiveness, and ease of use. However, the literature on effects of ultraviolet (UV) light spectra and doses on pathogen reduction is still contradictory. METHODS: We tested the effectiveness of killing Escherichia coli following RUV exposure with one broad-spectrum and two narrow-spectrum light sources centered at 311 and 365 nm and at successively higher doses by limited dilution survival assays. After comparing the effectiveness of E coli and phage inactivation (n = 6) and the changes in PLT count and metabolism caused by RUV treatment with optimized UV light at increasing doses, we confirmed our results by using four model virus systems that represent common TTIs, as well as PLT function and activation assays at an optimized light dose. RESULTS: The narrow-spectrum UV, centered at 311 nm, optimally reduced the E coli titer with a light dose ≥8.11 J/mL, resulting in the same trend of E coli and phage reduction at different light doses. At 8.11 J/mL, 311-nm narrow-spectrum UV had a good inactivation effect on E coli and phages, eliminating many viruses, and resulted in acceptable PLT quality after RUV treatment and during storage for 4 days. CONCLUSIONS: Our data suggest restricting exposure to narrow-spectrum UV centered at 311 nm can increase E coli elimination and potentially optimize virus titer reduction without significantly compromising PLT quality.