COVID-19 convalescent plasma cohort study: Evaluation of the association between both donor and recipient neutralizing antibody titers and patient outcomes.

BACKGROUND: Current evidence regarding COVID-19 convalescent plasma (CCP) transfusion practices is limited and heterogeneous. We aimed to determine the impact of the use of CCP transfusion in patients with previous circulating neutralizing antibodies (nAbs) in COVID-19. METHODS: Prospective cohort including 102 patients with COVID-19 transfused with ABO compatible CCP on days 0-2 after enrollment. Clinical status of patients was assessed using the adapted World Health Organization (WHO) ordinal scale on days 0, 5, and 14. The nAbs titration was performed using the cytopathic effect-based virus neutralization test with SARS-CoV-2 (GenBank MT126808.1). The primary outcome was clinical improvement on day 14, defined as a reduction of at least two points on the adapted WHO ordinal scale. Secondary outcomes were the number of intensive care unit (ICU)-free days and the number of invasive mechanical ventilation-free days. RESULTS: Both nAbs of CCP units transfused (p < 0.001) and nAbs of patients before CCP transfusions (p = 0.028) were associated with clinical improvements by day 14. No significant associations between nAbs of patients or CCP units transfused were observed in the number of ICU or mechanical ventilation-free days. Administration of CCP units after 10 days of symptom onset resulted in a decrease in ICU-free days (p < 0.001) and mechanical ventilation-free days (p < 0.001). CONCLUSION: Transfusion of high titer nAbs CCP units may be a determinant in clinical strategies against COVID-19. We consider these data as useful parameters to guide future CCP transfusion practices.

Hematopoietic Chimera in a Male Blood Donor and His Dizygotic Twin Sister.

Twin hematopoietic chimera in humans is a phenomenon that was discovered accidentally and the prevalence of which remains unclear. The resolution of chimera cases requires studying family medical records, data analysis, and investigations of hematopoietic cells and cells from other tissues. The interactions among ABO, Lewis, and secretor histo-blood group systems are explored to resolve cases of hematopoietic chimera. Here we report a rare case of hematopoietic chimera where twins present a mixed field reaction in the ABO, Rh, and Kidd red blood cell phenotyping. Using red blood cells separated from the mixed field as well as molecular approaches and investigations of family members, we identify inconsistent genotypes with the Mendelian inheritance pattern when comparing the peripheral blood with the buccal epithelium of the male twin and his twin sister. Analysis of the ABO, Lewis, and secretor phenotypes, and genomic DNA from buccal epithelium showed the genotypes ABO*A1.01/ABO*B.01 and FUT2*01N.02/ FUT2*01N.02 in the male twin and the genotypes ABO*O.01.01/ABO*O.01.02 and FUT2*01/FUT2*01 in the female twin. The results of the HLA-DRB1 genotyping showed inconsistency between the male and his twin sister. We conclude that the serological analyses combined with molecular approaches used in this study are good tools to resolve cases of hematopoietic chimera.

Analysis of HCV quasispecies dynamic under selective pressure of combined therapy.

BACKGROUND: The quasispecies composition of Hepatitis C virus (HCV) could have important implications with regard to viral persistence and response to interferon-based therapy. The complete NS5A was analyzed to evaluate whether the composition of NS5A quasispecies of HCV 1a/1b is related to responsiveness to combined interferon pegylated (PEG-IFN) and ribavirin therapy. METHODS: Viral RNA was isolated from serum samples collected before, during and after treatment from virological sustained responder (SVR), non-responder (NR) and the end-of-treatment responder patients (ETR). NS5A region was amplified, cloned and sequenced. Six hundred and ninety full-length NS5A sequences were analyzed. RESULTS: This study provides evidence that lower nucleotide diversity of the NS5A region pre-therapy is associated with viral clearance. Analysis of samples of NRs and the ETRs time points showed that genetic diversity of populations tend to decrease over time. Post-therapy population of ETRs presented higher genetic distance from baseline probably due to the bottleneck phenomenon observed for those patients in the end of treatment. The viral effective population of those patients also showed a strong decrease after therapy. Otherwise, NRs demonstrated a continuous variation or stability of effective populations and genetic diversity over time that did not seem to be related to therapy. Phylogenetic relationships concerning complete NS5A sequences obtained from patients did not demonstrate clustering associated with specific response patterns. However, distinctive clustering of pre/post-therapy sequences was observed. In addition, the evolution of quasispecies over time was subjected to purifying or relaxed purifying selection. Codons 157 (P03), 182 and 440 (P42), 62 and 404 (P44) were found to be under positive selective pressure but it failed to be related to the therapy. CONCLUSION: These results confirm the hypothesis that a relationship exists between NS5A heterogeneity and response to therapy in patients infected with chronic hepatitis C.

HCV-RNA PCR as a screening test on blood donors pools

O objetivo desse trabalho foi investigar o uso da reaçäo em cadeia da polimerase como um teste auxiliar para o vírus da hepatite C. Nós testamos 1800consecutivas doaçöes de sangue estocada de doadores voluntários de Säo Paulo, Brasil. Trinta e seis "pools" de 50 amostras (2ul cadaforam submetidos a amplificaçäo pela reaçäo em cadeia da polimerase por meio do sistema amplicor HCV (Roche). Reatividade em uma reaçäo por ummunoblot (RIBA 3.0, Ortho Diagnostics) foi considerada "gold standard". A reaçäo em cadeia da polimerase apresentou uma sensibilidade de 66 por cento e especificidade superior a 99,9 por cento. ELISA mostrou uma especificidade de 99,44 por cento. Três "pools" contendo pelo menos um ELISA positivo RIBA confimou uma amostra apresentando um resultado negativo da reaçäo em cadeia de polimerase. Aquelas amostras foram submetidas novamente a Amplicor individual e uma análise de "nested" reaçäo em cadeia da polimerase "in house". Foi mostrado que o sistema de pool de reaçäo em cadeia da polimerase, usando Amplicor HCV Roche, é viável e específico, mas incabível para a rotina de um banco de sangue devido a necessidade de "splitting" e retestagem de pools positivos enquanto as unidades de sangue correspondentes permanecem temporariamente bloqueadas. Além do mais, o método näo alcançou a sensibilidade desejada ("pools" contendo amostras positivas foram contabilizados como negativos), levando à conclusäo que a testagem individual de doaçöes é o objetivo final a ser alcançado.