This undated handout picture released by Cell Press on March 6, 2026 shows a Snake reptarenavirus alone, without deltavirus. Microbes still hold surprises. Researchers have just discovered how tiny viruses slip inside other viruses to penetrate and infect a cell. 'Deltaviruses are transmitted via a viral Trojan horse,' according to a study published on March 6, 2026 in Cell, one of the most prestigious biology journals, led by researchers from the CNRS. (Photo by Handout / Cell Press / AFP via Getty Images) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / CELL PRESS / HANDOUT" - HANDOUT - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS