1. The use of an “activating pituitary adenylate cyclase polypeptide” (PACAP) in the preparation of a composition for the treatment of viral infections and infectious diseases caused by viruses in aquatic organisms. The use according to claim 1, where PACAP is obtained a) isolation from its natural source, b) synthetically or c) recombinant DNA technology. The use of claim 2, wherein the PACAP is a polypeptide sequence secreted in fish. The use according to claims 1-3, where PACAP is used in an aquatic organism selected from the group consisting of salmon, flagellum shrimps and bivalve mollusks. 5. The use according to claim 1, where PACAP is used in the therapeutic treatment of viral infections caused by viruses of the families Herpesviridae, Papovaviridae, Togaviridae, Retroviridae, Reoviridae, Birnaviridae and Picornaviridae. Composition for the treatment of viral diseases and infectious diseases caused by viruses in aquatic organisms containing a “pituitary activating adenylate cyclase polypeptide” (PACAP). 7. The composition according to claim 6, wherein the PACAP is obtained a) by isolation from its natural source, b) synthetically, or c) by recombinant DNA technology. The composition according to claim 6, characterized in that it is administered orally, by injection or by immersion in a bath. A composition according to claims 7 and 8, characterized in that PACAP is a polypeptide sequence secreted in fish. A veterinary combination containing a “pituitary activating pituitary adenylate cyclase polypeptide” (PACAP) and an antiviral molecule. 11. The combination of claim 10, wherein the PACAP is obtained a) by isolation from its natural source, b) synthetically, or c) recombinant DNA technology. The combination of claim 10, wherein the antiviral molecule is a ribav1. Применение "активирующего аденилатциклазу гипофиза полипептида" (PACAP) в получении композиции для лечения вирусных инфекций и инфекционных заболеваний, вызываемых вирусами, у водных организмов.2. Пр
