呼吸道融合病毒及疫苗與單株抗體的臨床應用

Respiratory Syncytial Virus and the Clinical Application of Vaccines and Monoclonal Antibodies

呼吸道融合病毒（Respiratory Syncytial Virus，RSV）為全球嬰幼兒與老年族群下呼吸道感染的重要致病原之一，幾乎所有兒童在生命早期皆曾感染，並對高齡者與多重共病患者造成顯著的疾病負擔。RSV為具包膜之單股反鏈RNA病毒，依抗原性可分為A與B兩大亞型，其中融合蛋白（F protein）為主要免疫保護性抗原，近年對融合前F蛋白（pre-fusion F protein，preF）結構的深入解析，為疫苗與單株抗體的研發奠定關鍵基礎。
流行病學顯示，RSV於不同氣候區域具有明顯季節差異，COVID-19疫情後其流行型態與年齡分布亦出現顯著改變。臨床表現依年齡而異，嬰幼兒常以細支氣管炎或肺炎表現，老年人與高風險成人則可能因RSV感染導致慢性心肺疾病惡化，甚至出現心血管併發症。目前RSV治療以支持性療法為主，抗病毒藥物僅限於特定重症族群。
在預防策略方面，除基本感染管制措施外，被動免疫與主動免疫已成為控制RSV的重要進展。RSV特異性單株抗體（如palivizumab與nirsevimab）可有效降低高風險嬰幼兒之住院率；而以穩定化preF蛋白為標的的RSV疫苗，已陸續獲准用於孕婦及老年族群，臨床試驗顯示其對預防RSV下呼吸道疾病具有良好效力。

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and older adults worldwide. Nearly all children are infected during early childhood, and RSV imposes a substantial disease burden on older adults and individuals with multiple comorbidities. RSV is an enveloped, negativesense single-stranded RNA virus classified into two antigenic subgroups, A and B. The RSV fusion (F) protein represents the principal target of protective immunity. Recent advances in the structural characterization of the prefusion F (preF) protein have provided a critical foundation for the development of effective vaccines and monoclonal antibodies.
Epidemiological studies have demonstrated marked seasonal variation in RSV circulation across climatic regions. Furthermore, significant changes in transmission patterns and age distribution were observed following the COVID-19 pandemic. Clinical manifestations vary by age, with infants commonly presenting with bronchiolitis or pneumonia, while older adults and high-risk populations may experience exacerbations of chronic cardiopulmonary diseases and, in some cases, cardiovascular complications. Currently, management of RSV infection remains primarily supportive; antiviral therapy is reserved for selected patients with severe disease.
In terms of prevention, in addition to standard infection control measures, both passive and active immunization strategies have emerged in RSV control. RSV-specific monoclonal antibodies, such as palivizumab and nirsevimab, have been shown to significantly reduce hospitalization rates among high-risk infants. Furthermore, RSV vaccines targeting the stabilized preF protein have recently been approved for use in pregnant women and older adults, with clinical trials demonstrating favorable efficacy in preventing RSV-associated lower respiratory tract disease.