The structural spike (S) glycoprotein of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) plays an essential role in infection and is an important target for neutralizing antibody recognition. Mutations in the S gene can generate variants of concern (VOCs), which improve “viral fitness” through selective or survival advantages, such as increased ACE-2 receptor affinity, infectivity, viral replication, higher transmissibility, resistance to neutralizing antibodies and immune escape, increasing disease severity and reinfection risk. Five VOCs have been recognized and include B.1.1.7 (U.K.), B.1.351 (South Africa), P.1 (Brazil), B.1.617.2 (India), and B.1.1.529 (multiple countries). In this review, we addressed the following critical points concerning VOCs: a) characteristics of the SARS-CoV-2 VOCs with mutations in the S gene; b) possible evasion of variants from neutralizing antibodies generated through vaccination, previous infection, or immune therapies; c) potential risk of new pandemic waves induced by the variants worldwide; and d) perspectives for further studies and actions aimed at preventing or reducing the impact of new variants during the current COVID-19 pandemic.

To evaluate the genetic variability of human parvovirus B19, the complete coding region of the VP1/VP2 structural proteins of 29 B19 isolates obtained from 25 infected patients were sequenced and compared with each other and with two previously published B19 isolates. The VP1/VP2 gene was amplified by PCR using B19-specific oligonucleotide primers and the amplification products were sequenced directly. Overall, the average nucleotide and predicted amino acid identity among B19 isolates was high. Sequential virus isolates from the same cases and isolates obtained from two cases linked by transmission in the same household were essentially identical. Sequence variation was minimal among isolates obtained from a single community-wide B19 outbreak, ranging between 0 and 10 (0,4%) base substitutions, although there appeared to be more than one genetic lineage circulating in the outbreak. A comparison with 18 additional isolates from distinct epidemiological settings found greater variability. These isolates differed from each other by between 11 (0.5%) and 112 (4.8%) base substitutions. B19 isolates from Xi'an, China, were significantly different from other isolates at both the nucleoticle and amino acid levels, and were more closely related to a single isolate from Japan, obtained 10 years earlier, than to isolates from other countries. Isolates examined in this study included distinct genotypes from patients with similar clinical presentations and similar genotypes from patients with diverse clinical presentations. These data suggest that geographically defined genetic lineages of B19 may exist and that no particular B19 genotype was associated with a particular clinical outcome.

BackgroundThe effects of convalescent plasma (CP) therapy hospitalised patients with coronavirus disease 2019 (COVID-19) remain uncertain. This study investigates the effect CP on clinical improvement in these patients.MethodsThis is an investigator-initiated, randomised, parallel arm, open-label, superiority clinical trial. Patients were randomly (1:1) assigned to two infusions of CP plus standard of care (SOC) or SOC alone. The primary outcome was the proportion of patients with clinical improvement 28 days after enrolment.ResultsA total of 160 (80 in each arm) patients (66.3% were critically ill and 33.7%, severe) completed the trial. The median age was 60.5 years (interquartile range [IQR], 48–68), 58.1% were men and the median time from symptom onset to randomisation was 10 days (IQR, 8–12). Neutralising antibodies titres >1:80 were present in 133 (83.1%) patients at baseline. The proportion of patients with clinical improvement on day 28 was 61.3% in the CP+SOC and 65.0% in the SOC group (difference, −3.7%; 95% Confidence Interval [CI], −18.8%-11.3%). The results were similar in the subgroups of severe and critically ill. There was no significant difference between CP+SOC and SOC groups in prespecified secondary outcomes, including 28-day mortality, days alive and free of respiratory support and duration of invasive ventilatory support. Inflammatory and other laboratorial markers values on days 3, 7 and 14 were similar between groups.ConclusionsCP+SOC did not result in a higher proportion of clinical improvement on at day 28 in hospitalised patients with COVID-19 compared to SOC alone.

Yellow fever virus RNA is usually detected in blood of infected humans. We detected virus RNA in urine and semen samples from a convalescent patient. A complete virus genome was sequenced for an isolate from a urine sample. This virus had a South American I genotype and unique synapomorphic changes.

Samples from sera and oral swabs from fifteen marmosets (Callithrix jacchus) and nine capuchin-monkeys (Sapajus libidinosus) captured in Ceara State in Brazil were tested for Zika virus. Samples were positive by Real time PCR and sequencing of the amplified product from a capuchin monkey showed 100% similarity to other ZIKV from South America. This is the first report on ZIKV detection among Neotropical primates.

Background: Since aging affects the immune responses against vaccination, the present study evaluated the effects of L-glutamine (Gln) supplementation in the humoral and cellular immune responses in elderly subjects, practitioners or not, of physical exercise training. Methods: Eighty-four elderly people (aged 72.6 ± 6.1), non-practitioners (NP, n = 31), and practitioners of combined-exercise training (CET, n = 53) were submitted to Influenza virus vaccination and supplemented with Gln (0.3 g/kg of weight + 10 g of maltodextrin, groups: NP-Gln (n = 14), and CET-Gln (n = 26)), or placebo (10 g of maltodextrin, groups: NP-PL (n = 17), and CET-PL (n = 27)). Blood samples were collected pre (baseline) and 30 days post-vaccination and supplementation. Results: Comparing with the baseline values, whereas the NP-Gln and CET-PL groups showed higher specific-IgM levels, the CET-Gln group showed higher specific-IgM and IgA levels post-vaccination. The titer rate of hemagglutination inhibition was higher in the CET-Gln, NP-PL, and NP-Gln groups post-vaccination than baseline values. The absolute number of naive and effector CD4+ T cells was higher especially in the NP-Gln and CET-Gln groups, whilst activated CD4+ T cells were higher in CET subgroups post-vaccination. Conclusion: Our results showed that both l-glutamine supplementation and combined-exercise training can improve the immune responses to the Influenza virus vaccine in elderly subjects.

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