Polio virus figure 2 (IMAGE) Umea University Caption When new virus particles are prepared for release in small packets (called vesicles), the virus makes sure that only those virus particles that have been loaded with the virus genome, and thus become infectious, are packaged. Several examples of that process are shown (infectious particles in red, vesicles in blue). Credit Selma Dahmane, Umeå University, Sweden Usage Restrictions Media use License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.