Immunology, virology, and epidemiology of flaviviruses and other emerging viruses

表征保护性抗DENV抗体。 结合和中和抗体的特定浓度与登革热疾病的保护和增强相关（Katzelnick et al. Science 2017，2020; Katzelnick et al. PNAS 2016）。然而，现有的测定是粗糙的，甚至对于可以在体内增强的抗体也检测到中和。利用最近对黄病毒免疫学的见解，我们正在开发和评估检测方法，以测试结合DENV病毒粒子上的四级表位的抗体是否与登革热和寨卡疫苗研究中的疾病保护相关。通过合作，我们正在评估其他自然感染队列中的抗体质量（预印本：https：//pubmed.ncbi.nlm.nih.gov/37502957/）。我们还鉴定了广泛中和的抗DENV抗体，其比先前使用快速抗体发现平台鉴定的那些更有效（临时专利申请序列号：63/464，370）。 登革热传播和流行的形成因素。 在连续DENV感染后，结合抗体减弱多年，有时达到首次DENV感染后观察到的水平，表明两次感染后的免疫力可能不是终身的（Katzelnick et al. Sci Trans Med 2021）。我们发现，即使在高度免疫的成年人中，DENV再暴露也会继续提高抗体水平，并开发了一个数学模型，该模型表明增强有助于群体免疫，并有助于解释观察到的登革热流行动态。继续我们先前的工作，显示四种DENV血清型在抗原上是多样的，并且经历朝向和远离共循环血清型的进化周期。（Katzelnick et al. Science 2015，2021; Huang et al. PLoS Pathogens 2022），我们与其他人合作评估菌株之间的特异性抗原距离是否与疾病风险增加相关（预印本：https：//pubmed.ncbi.nlm.nih.gov/37577717/）。最后，我们以厄瓜多尔为例，评估了导致登革热在全球范围内蔓延的因素（预印本：https：//pubmed.ncbi.nlm.nih.gov/37398346/）。 使用登革热疫苗建立保护性免疫决定因素的模型。 现有的登革疫苗是四价的，旨在诱导登革型特异性免疫，而具有不同血清型的自然连续登革病毒感染被认为诱导针对共享表位的广泛保护性免疫。我们发表了一篇关于混合和匹配许可的登革热疫苗作为诱导保护性免疫而不增加增强风险的方法的潜力的观点文章（Odio和Katzelnick Vaccine 2023）。为了鉴定连续DENV感染如何诱导广泛保护性免疫的机制，我们已经建立了I期临床试验（n=45名参与者），以在没有、一种或多于一种先前天然DENV感染的健康成人中安全地模拟用单价登革热疫苗rDEN 3d 30/31-7164的DENV感染（Odio等人，BMC Infectious Diseases 2023; ClinicalTrials.gov Identifier NCT 05691530）。受试者在接种后0-15天接受密切随访，并在第28、57、90、180和365天进行回访，一个亚组（n=15）在第15和28天接受细针穿刺，以表征接种中心的反应。我们正在评估：1）疫苗接种前感染史和免疫特征是否与安全性、疫苗病毒血症和症状以及免疫原性相关，2）疫苗接种如何调节保护性抗体的强度、持久性和广度，以及3）随着时间的推移，单细胞水平的细胞表面、活化和转录组学特征。

Characterizing protective anti-DENV antibodies. Specific concentrations of binding and neutralizing antibodies are associated with protection and enhancement of dengue disease (Katzelnick et al. Science 2017, 2020; Katzelnick et al. PNAS 2016). However, existing assays are crude, with neutralization detected even for antibodies that can enhance in vivo. Drawing on recent insights into flavivirus immunology, we are developing and evaluating assays to test whether antibodies that bind quaternary epitopes on the DENV virion correlate with protection against disease in dengue and Zika vaccine studies. Through collaborations, we are evaluating antibody quality in other natural infection cohorts (preprint: https://pubmed.ncbi.nlm.nih.gov/37502957/). We have also identified broadly neutralizing anti-DENV antibodies that are more potent than those identified previously using a rapid antibody discovery platform (provisional patent application serial number: 63/464,370). Factors shaping of dengue transmission and epidemics. After sequential DENV infection, binding antibodies wane for many years, sometimes to the level observed following first DENV infection, suggesting immunity after two infections may not be life-long (Katzelnick et al. Sci Trans Med 2021). We find that DENV re-exposure continues to boost antibody levels even in highly immune adults, and developed a mathematical model that shows boosts contribute to herd immunity and help explain observed dengue epidemic dynamics. Continuing our previous work showing that the four DENV serotypes are antigenically diverse and undergo cycles of evolving toward and away from co-circulating serotypes (Katzelnick et al. Science 2015, 2021; Huang et al. PLoS Pathogens 2022), we have collaborated with others to evaluate if specific antigenic distances between strains are associated with increased risk of disease (preprint: https://pubmed.ncbi.nlm.nih.gov/37577717/). Finally, we have evaluated factors contributing to the expansion of dengue globally using Ecuador as a case study (preprint: https://pubmed.ncbi.nlm.nih.gov/37398346/). Modeling the determinants of protective immunity using dengue vaccines. Existing dengue vaccines are tetravalent and aim to induce serotype-specific immunity, whereas natural sequential DENV infection with distinct serotypes is thought to induce broadly protective immunity against shared epitopes. We published a perspective piece on the potential for mix and match of licensed dengue vaccines as an approach for inducing protective immunity without increasing risk of enhancement (Odio and Katzelnick Vaccine 2023). To identify mechanisms of how sequential DENV infection induces broad protective immunity, we have established a Phase I clinical trial (n=45 participants) to safely model DENV infection with a monovalent dengue vaccine, rDEN3d30/31-7164, in healthy adults with no, one, or more than one previous natural DENV infections (Odio et al. BMC Infectious Diseases 2023; ClinicalTrials.gov Identifier NCT05691530). Participants are being closely followed from 0-15 days post-vaccination with return visits at days 28, 57, 90, 180, and 365, and a subset (n=15) are undergoing fine needle aspiration at days 15 and 28 to characterize germinal center responses. We are evaluating: 1) whether pre-vaccination infection history and immune characteristics are associated with safety, vaccine viremia and symptoms, and immunogenicity, 2) how vaccination modulates magnitude, durability, and breadth of protective antibodies, and 3) cellular surface, activation, and transcriptomic signatures at the single-cell level over time.