Seroprevalence and cross-reactivity of neutralizing antibodies to six types of adenoviruses

Background The use of adenoviral vector vaccines is an effective way to induce an antiviral immune response. Most vaccines used worldwide are based on human adenovirus type 5 (Ad5). Pre-existing natural immunity to Ad5 is a limitation to the frequent use of Ad5-based vectors in gene therapy and vaccination. In the present study, we assessed the seroprevalence and cross-reactivity of neutralizing antibodies to six adenovirus types: Ad1, Ad2, Ad5, Ad19, Ad26, and Ad37. Methods The study used immunological and virological research methods. Adenovirus vectors encoding the enhanced green fluorescent protein (EGFP) were developed by the N.F. Gamaleya National Research Center for Epidemiology and Microbiology. For seroprevalence and cross-neutralation study we used a panel of sera from 101 volunteers. Results The conducted correlation analysis showed a strong relationship between seropositivity and the geometric mean titer of neutralizing antibodies to adenovirus. An increase in antibody titers indicates the formation of a humoral immune response and population immunity. We determined that there is no cross-reactivity between NtAbs to Ad1, Ad2, Ad5 and Ad26. Conclusions Based on the presented data, we assume that Ad1 or Ad2 should be considered the most promising alternative candidates for the development of vaccine vectors.