People live in the infectious world. Bacteria and viruses accompany us from birth and throughout life, and sometimes cause dangerous diseases. And it is good when in a certain disease there are certain tangible symptoms, for example, in acute respiratory viral infections or an intestinal infection. Often, an infectious disease is hidden, has no clear symptoms and can be detected by chance, for example, viral hepatitis. The incidence of hepatitis of various etiologies is increasing throughout the world. On average, 5% of the population is infected with viral hepatitis. In Ukraine in 2015, 46,000 patients with hepatitis C and more than 20,000 patients with hepatitis B were registered, but the real picture of the infection level is at least an order of magnitude higher. In conditions of chronic immunodeficiency, which occurs due to viral damage to the liver, immune cells need support. Regulatory peptide defensin-1, which is part of the drug Arecur, can improve the performance of anti-infective immunity, and also has proven antiviral activity.