An 28-year-old man was hospitalized on the 7th day of illness with complaints of headache, general weakness, fever, and sore throat. All the groups of lymph nodes are enlarged to 1–3 cm in diameter. Palpation shows dense, elastic, and slightly painless lymph nodes that are not matted together. Enlarged tonsils are covered with purulent plaque. The liver is +3 cm. In the blood: leukocytosis, relative lymphomonocytosis, virocytes – 15%. Make the right diagnosis: