The study found that thymogen, a peptide from the thymus, doesn’t directly kill flu viruses but can help the body’s immune system fight them better, especially for one type of flu in mice. It wasn’t effective in chick embryos and didn’t work against the other flu type.

To evaluate the possible antiviral activity of a number of peptide bioregulators, an acute influenza infection was induced in developing chick embryos and mice. Four peptide preparations were used: two medicinal peptide preparations of the thymus (thymalin and thymogen) and peptide preparations obtained from the tracheal mucosa (PTM) and lung parenchyma (PLP) of calves according to the technology used for obtaining thymalin. For control, remantadin (for type A virus) and adapromin (for type B virus) were used as antiviral remedies. In experiments on mice, the preparations were introduced 24 hours and 1 hour before and 24, 48 and 72 hours after intranasal challenge. The effectiveness of the preparations was evaluated by the death rate of the animals. In case of type A virus the effectiveness of the preparations was distributed as follows: remantadin > thymogen > thymalin > > PTM. In case of type B virus, adapromin and PTM were found to produce a similar effect, while the preparations of the thymus and PLP had no influence on the death rate of the animals. In experiments on developing chick embryos, none of the peptide preparations under study had any influence on the infection caused by the viruses of both hypes. The results obtained in this investigation are indicative of the absence of direct antiviral activity in the tested peptide preparations. At the same time thymalin, thymogen and PTM significantly enhance the immunological resistance of the body to virus infection, different activity spectra of PTM and the thymus being indicative of the specific nature of their action.