Ubiquitous surface protein A2 (UspA2) (UspA2)

Ubiquitous surface protein A2 (UspA2) is a major outer membrane protein of the gram-negative bacterium Moraxella catarrhalis, which is a significant cause of respiratory tract infections. As a member of the trimeric autotransporter adhesin family, UspA2 is essential for bacterial attachment to host tissues by binding to extracellular matrix proteins such as laminin and fibronectin [3, 4]. Beyond adhesion, UspA2 is a key factor in serum resistance, allowing the pathogen to survive in human serum by recruiting complement inhibitors like C4b-binding protein (C4BP) and vitronectin to the bacterial surface [2, 5]. This recruitment effectively blocks the classical and alternative complement pathways, preventing the formation of the membrane attack complex [2]. Given its critical role in immune evasion and its presence in nearly all clinical isolates, UspA2 is a primary target for the development of vaccines and therapeutic antibodies [1, 5]. Current research focuses on utilizing conserved domains of UspA2 to induce broad-spectrum bactericidal immunity against various strains of M. catarrhalis, particularly for the prevention of otitis media in pediatric populations and exacerbations of chronic obstructive pulmonary disease (COPD) in adults [1, 5].

Other names

UspA2Moraxella catarrhalis ubiquitous surface protein A2Outer membrane protein UspA2OMP UspA2

Induction of neutralizing and bactericidal antibodies to prevent bacterial colonization and immune evasion [1, 5]