Development of mRNA vaccines against respiratory syncytial virus (RSV).

Respiratory syncytial virus (RSV) is a single-stranded negative-sense RNA virus that is the primary etiologic pathogen of bronchitis and pneumonia in infants and the elderly. Currently, no preventative vaccine has been approved for RSV infection. However, advances in the characterization, and structural resolution, of the RSV surface fusion glycoprotein have revolutionized RSV vaccine development by providing a new target for preventive interventions. In general, six different approaches have been adopted in the development of preventative RSV therapeutics, namely, particle-based vaccines, vector-based vaccines, live-attenuated or chimeric vaccines, subunit vaccines, mRNA vaccines, and monoclonal antibodies. Among these preventive interventions, MVA-BN-RSV, RSVpreF3, RSVpreF, Ad26. RSV.preF, nirsevimab, clesrovimab and mRNA-1345 is being tested in phase 3 clinical trials, and displays the most promising in infant or elderly populations. Accompanied by the huge success of mRNA vaccines in COVID-19, mRNA vaccines have been rapidly developed, with many having entered clinical studies, in which they have demonstrated encouraging results and acceptable safety profiles. In fact, Moderna has received FDA approval, granting fast-track designation for an investigational single-dose mRNA-1345 vaccine against RSV in adults over 60 years of age. Hence, mRNA vaccines may represent a new, more successful, chapter in the continued battle to develop effective preventative measures against RSV. This review discusses the structure, life cycle, and brief history of RSV, while also presenting the current advancements in RSV preventatives, with a focus on the latest progress in RSV mRNA vaccine development. Finally, future prospects for this field are presented.

Estimating the Neovascularity of Human Finger Tendon Through High-Frequency Ultrasound Micro-Doppler Imaging.

OBJECTIVE: Neovascularization of injured tendons prolongs the proliferative phase of healing, but prolonged neovascularization may cause improper healing and pain. Currently, ultrasound Doppler imaging is used for measuring the neovascularization of injured tendons (e.g., Achilles tendon). However, the resolution of state-of-the-art clinical ultrasound machines is insufficient for visualizing the neovascularization in finger tendons. In this study, a high-frequency micro-Doppler imaging (HFµDI) based on 40-MHz ultrafast ultrasound imaging was proposed for visualizing the neovascularization in injured finger tendons during multiple rehabilitation phases. METHOD: The vessel visibility was enhanced through a block-wise singular value decomposition filter and several curvilinear structure enhancement strategies, including the bowler-hat transform and Hessian-based vessel enhancement filtering. HFµDI was verified through small animal kidney and spleen imaging because the related vessel structure patterns of mice are well studied. Five patients with finger tendon injuries underwent HFµDI examination at various rehabilitation phases after surgery (weeks 11-56), and finger function evaluations were performed for comparisons. RESULTS: The results of small animal experiments revealed that the proposed HFµDI provides excellent microvasculature imaging performance; the contrast-to-noise ratio of HFµDI was approximately 15 dB higher than that of the conventional singular value decomposition filter, and the minimum detectable vessel size for mouse kidney was 35 µm without the use of contrast agent. In the human study, neovascularization was clearly observed in injured finger tendons during the early phase of healing (weeks 11-21), but it regressed from week 52 to 56. Finger rehabilitation appears to help reduce neovascularization; neovascular density decreased by approximately 1.8%-8.0% in participants after 4 weeks of rehabilitation. CONCLUSION: The experimental results verified the performance of HFµDI for microvasculature imaging and its potential for injured finger tendon evaluations.