The 57th Annual Meeting of the Japanese Society for Pediatric Infectious Diseases

https://jspid57.umin.jp/index.html

Dates: Saturday, November 8, 2025 - Sunday, November 9, 2025

Venue: Grand Nikko Tokyo Bay Maihama

P-9

Molecular Basis for Antigenic Stability of Measles Virus

Kiyotaka Konishi1, Ayumi Hyodo1, Kaede Tashiro2, Fumio Seki3, Takao Segawa4, Takuya Itou4, Yuki Kitai1, Yukiko Akahori1, Hiroshi Kato1, Makoto Takeda1

1Department of Microbiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo

2Department of Molecular Virology, Graduate School of Medical and Dental Sciences, Institute of Science Tokyo

3Department of Respiratory Viruses, National Institute of Infectious Diseases, Japan Institute for Health Security

4Laboratory of Preventive Veterinary Medicine and Animal Health, Department of Veterinary Medicine, College of Bioresource Sciences

【Objective】Measles virus is a single serotype and has shown no antigenic changes for at least half a century. This study aimed to elucidate the molecular basis of measles virus antigenic stability.

Methods: 1. Antigenic cross-reactivity among various morbilliviruses (including canine distemper virus, cetacean morbillivirus, and phocine distemper virus) was evaluated using sera derived from infected animals (human, dog, dolphin). 2. Species specificity of SLAM receptor utilization by various morbilliviruses was assessed. 3. Using viral engineering and optogenetic techniques, we constructed a novel biological containment system for measles virus and used this system to examine viral escape from neutralizing antibodies in human serum.

【Results】1. No significant antigenic differences were observed between the epidemic strain and vaccine strain of measles virus. In contrast, antigenic cross-reactivity between different morbilliviruses was markedly low, at 1/10 or less. 2. Measles virus and various animal morbilliviruses could utilize SLAM from diverse animal species as receptors. 3. Repeated escape experiments in the presence of neutralizing serum failed to induce escape mutations in measles virus.

【Conclusion】The low antigenic cross-reactivity among morbilliviruses indicates these viruses possess a latent capacity to tolerate antigenic variation. On the other hand, despite measles virus being able to utilize SLAM from other animal species such as dogs and dolphins, the fact that antigenicity differs greatly between morbilliviruses suggests that the conservation of the SLAM binding site does not significantly contribute to antigenic stability. It is likely that measles virus has difficulty acquiring escape mutations because a significant number of amino acid substitutions are required simultaneously, exceeding its mutation capacity.