Results of preclinical investigation of new antiviral Anaferon for children
Upon the basis of our laboratory research at APcis, we have studied the antiviral efficacy of a novel drug, Anaferon for children (antibodies to interferon gamma in released-active form manufactured by OOO “NPF “MATERIA MEDICA HOLDING”, Russia) alone or in combination with standard antiviral drug (oseltamivir phosphate, F. Hoffmann–La Roche Ltd., Switzerland) in various in vivo experimental models of influenza infection in mice, since 2008. The efficacy was assessed not only against important pandemic strain of Influenza (А/H1N1 (California/07/2009v), but also against other influenza А strain, A/H3N8 (Equi2/Miami/1/63) that show a severe pathogenicity in rodents. As there is often a great variability of strains during seasonal Flu, drug candidates with a broad antiviral spectrum are scrutinized with great expectations.
In vivo experiment in murine model of А/H1N1 (California/07/2009v) infection at the dose of 10 LD50 has shown that Anaferon for children (20ml/kg/day) was effective against the virus both alone and in combination with oseltamivir (10 mg/kg/day). More precisely, administration of Anaferon for children alone has led to a later disease onset (+48 hours) after viral nasal challenge and to a decrease in the mortality rate (-20%). Combined treatments with Oseltamivir phosphate and Anaferon for children has also decreased the mortality as compared to Oseltamivir only group.
The mice’s health measured by bodyweight variations suggests that mice treated with Anaferon for children alone or in combination with oseltamivir phosphate were less affected by the challenge and that surviving mice recovered sooner than placebo treated mice. Anaferon for children was as efficient as oseltamivir (10 mg/kg/day) in Balb/c mice, but the most prominent antiviral properties were shown for the combination of two drugs (including later disease onset and overall reduction in severity of the infection).
In the model of A/H3N8 (Equi2/Miami/1/63) infection at the dose of 5 LD50, Anaferon for children (0,4 ml/mouse/day) was used in preventative and curative oral dosing regimen and was more effective than oseltamivir at the dose of 4 mg/kg/day, providing statistically significant reduction of the death rate over time. Both Anaferon for children and oseltamivir phosphate treatments reduced the duration of the clinical signs of infection and enhanced animals survival when compared to placebo.
Therefore, the results of our experiments have shown that the efficacy of Anaferon for children was comparable to that of oseltamivir phosphate. Moreover, it was shown that the antiviral activity of oseltamivir phosphate could be improved by Anaferon for children.
A following study on possible synergism of action of Anaferon for children and oseltamivir phosphate has been conducted in 2015 in the Flu Laboratory of Pasteur Institute in collaboration with us.
Anaferon for children has shown a statistically significant decrease in viral copies number of pandemic H1N1 strain in the infected cell culture alone, and then was subsequently tested in 3 different volumes in combination with oseltamivir at minimal effective dose (20nM) against different Influenza H1N1 strains (A/Danmark/524/09 Sensitive H1N1p and A/Danmark/528/09 Resistant H1N1p). Anaferon for children has decreased viral multiplication in presence of oseltamivir which was estimated by qRT-PCR quantification of the specific protein.
As expected, resistant H1N1 strain showed a complete resistance to the neuraminidase inhibitor (Oseltamivir at 20 nM). The addition of Anaferon for children to the same dose of oseltamivir has led to a significant antiviral effect for both Oseltamivir sensitive and resistant strains, H1N1pdm09 sen (A/Danemark/524/09 sen) and H1N1pdm09 res (A/Danemark/528/09 res), respectively. When combined with oseltamivir at 20nM, Anaferon for children tended to delay viral multiplication by approximately 24 hours.
These results suggest that the efficacy of Anaferon for children may be mediated by viral synthesis delay or inhibition, or by stimulation of cell endogenous cytokine production and engaging intracellular antiviral mechanisms, although this inhibition in a single dose – even applied prior to the viral challenge - is mild and incomplete. Anaferon’s eventual antiviral efficacy is similar with different Influenza strains causing flu epidemics but it is observed in the presence of oseltamivir at 20nM, and thus is compatible to a standard prescription level of the reference antiviral drug. The efficacy of Anaferon for children is additive to that of oseltamivir and the eventual increase in antiviral efficacy seems to be independent of neuraminidase inhibition, which was assessed in MUNANA fluorescence test.
Therefore, Anaferon for children has shown some antiviral activity in several in vitro and in vivo models of Influenza A infection, including pandemic influenza A/H1N1 both alone and in combination with oseltamivir and could be recommended as an effective product for treatment and prevention of influenza A infections in countries where efficacy and safety in man have been documented.