Enhancement of SARS-CoV-2 vaccine-induced immunity by a Toll-like receptor 7 agonist adjuvant

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is an enveloped positive-sense single-stranded RNA(ssRNA)virus responsible for the global COVID-19 pandemic.Although vaccines for SARS-CoV-2 have been developed and applied worldwide,research on vaccine adjuvant is lacking.Viral infections normally elicit a range of innate immune responses through the activation of pattern recognition receptors(PRRs).

Human Vγ9Vδ2-T cells efficiently kill influenzavirus-infected lung alveolar epithelial cells

γδ-T cells play an indispensable role in host defense against different viruses, including influenza A virus. However, whether these cells have cytotoxic activity against influenza virus-infected lung alveolar epithelial cells and subsequently contribute to virus clearance remains unknown. Using influenza virus-infected A549 cells, human lung alveolar epithelial cells, we investigated the cytotoxic activity of aminobisphosphonate pamidronate （PAM）-expanded human Vγ9Vδ2-T cells and their underlying mechanisms. We found that PAM could selectively activate and expand human Vγ9Vδ2-T cells. PAM-expanded human Vγ9Vδ2-T cells efficiently killed influenza virus-infected lung alveolar epithelial cells and inhibited virus replication. The cytotoxic activity of PAM-expanded Vγ9Vδ2-T cells was dependent on cell-to-cell contact and required NKG2D activation. Perforin-granzyme B, tumor-necrosis factor-related apoptosis-inducing ligand （TRAIL） and Fas-Fas ligand （FasL） pathways were involved in their cytotoxicity. Our study suggests that targeting γδ2-T cells by PAM can potentially offer an alternative option for the treatment of influenza virus.

Vγ9Vδ2-T lymphocytes have impaired antiviral function in small-for-gestational-age and preterm neonates

Preterm and small-for-gestational-age （SGA） neonates are vulnerable groups that are susceptible to various microbial infections. Vγ9Vδ2-T cells are critical components of the host immune system and have been demonstrated to play an important role in the defense against viral infection in adults. However, the characteristics of Vγ9Vδ2-T cells in children, especially the preterm and SGA populations, are poorly understood. Here, we examined the frequency and antiviral function of Vγ9Vδ2-T cells in neonates, including preterm, SGA and full-term babies. When compared to adults, neonates had a significantly lower percentage of Vγ9Vδ2-T cells in the blood. Upon influenza virus stimulation, neonatalVγ9Vδ2-T cells, especially from preterm and SGA babies, showed markedly decreased and delayed antiviral cytokine responses than those of adults. In addition, the antiviral responses of neonatal Vγ9Vδ2-T cells were positively correlated with gestational age and birth weight. Finally, a weaker expansion ofVγ9Vδ2-T cells by isopentenyl pyrophosphate （IPP） was shown in neonates than the expansion in adults. Our data suggest that the depressed antiviral activity and decreased frequency of Vγ9Vδ2-T cells may likely account for the high susceptibility to microbial infection in neonates, particularly in preterm and SGA babies. Improving Vγ9Vδ2-T -cell function of neonates may provide a new way to defend against virus infection.

Assessment of infectivity and the impact on neutralizing activity of immune sera of the COVID-19 variant,CAL.20C

Dear Editor,New variants of SARS-CoV-2 have been emerging since the initial outbreak in 2019;1 one of the latest ones was identified in Southern California in October 2020 and was subsequently detected in 26 other states in the United States as well as other countries as of January 2021.

mpaired NK cell antiviral cytokine response against nfluenza virus in small-for-gestational-age neonates

The neonates, particularly small-for-gestational-age （SGA） ones, are susceptible to various microbial infections. Natural killer （NK） cells are critical components of host innate immunity system and the main source of the inflammatory cytokines, which provide critical protection during the early phase of viral infections before the development of an appropriate adaptive immune response. However, little is known about the antiviral effects of NK cells in neonates especially the SGA population. Herein, a prospective descriptive study was performed to determine the differences of NK cell immunity among adults, appropriate-for gestational-age （AGA） and SGA neonates. Adults have much higher NK cell number in peripheral blood than that in cord blood from neonates. In response to influenza virus stimulation, neonatal NK cells, especially SGA baby cells, expressed significantly lower antiviral cytokines including perforin, interferon （IFN）-7 and tumor-necrosis factor （TNF）-α responses than adult NK cells. In addition, the antiviral cytokine responses of NK cells were positively correlated with neonatal birth weight. Our data suggested that the depressed antiviral activity and less frequency of NK cells are likely to be responsible for the high susceptibility to microbial infection in neonates, at least in part. Improving the function of innate immunity may provide a new way to defend virus infection.

The SARS-CoV-2 spike L452R-E484Q variant in the Indian B.1.617 strain showed significant reduction in the neutralization activity of immune sera

To assess the impact of the key non-synonymous amino acid substitutions in the RBD of the spike protein of SARS-CoV-2 variant B.1.617.1(dominant variant identified in the current India outbreak)on the infectivity and neutralization activities of the immune sera,L452R and E484Q(L452R-E484Q variant),pseudotyped virus was constructed(with the D614G background).The impact on binding with the neutralizing antibodies was also assessed with an ELISA assay.Pseudotyped virus carrying a L452R-E484Q variant showed a comparable infectivity compared with D614G.However,there was a significant reduction in the neutralization activity of the immune sera from non-human primates vaccinated with a recombinant receptor binding domain(RBD)protein,convalescent patients,and healthy vaccinees vaccinated with anmRNA vaccine.In addition,there was a reduction in binding of L452R-E484Q-D614G protein to the antibodies of theimmune sera fromvaccinated nonhuman primates.These results highlight the interplay between infectivity and other biologic factors involved in the natural evolution of SARS-CoV-2.Reduced neutralization activities against the L452R-E484Q variant will have an impact on health authority planning and implications for the vaccination strategy/newvaccine development.

DNA methylation markers in the diagnosis and prognosis of common leukemias

The ability to identify a specific type of leukemia using minimally invasive biopsies holds great promise to improve the diagnosis,treatment selection,and prognosis prediction of patients.Using genome-wide methylation profiling and machine learning methods,we investigated the utility of CpG methylation status to differentiate blood from patients with acute lymphocytic leukemia(ALL)or acute myelogenous leukemia(AML)from normal blood.We established a CpG methylation panel that can distinguish ALL and AML blood from normal blood as well as ALL blood from AML blood with high sensitivity and specificity.We then developed a methylation-based survival classifier with 23 CpGs for ALL and 20 CpGs for AML that could successfully divide patients into high-risk and low-risk groups,with significant differences in clinical outcome in each leukemia type.Together,these findings demonstrate that methylation profiles can be highly sensitive and specific in the accurate diagnosis of ALL and AML,with implications for the prediction of prognosis and treatment selection.