Amantadine resistance of clade 2.3.2 H5N1 Avian Influenza Virus from Waterfowl in Indonesia

The objective of this research was to know the sensitivity of H5N1 clade 2.3.2 AIV from Indonesia to antiviral drug (amantadine) through molecular and in vitro tests. The study was conducted by virus isolation and identification, nucleotide analysis, and susceptibility to the amantadine hydrocloride in MDCK cells. The study result represented that the mean EID₅₀isolates of H5N1 clade 2.3.2 AIV was determined of >10⁸EID₅₀/ml. The analysis of phylogenetic tree of M2 gene from six viruses of H5N1 clade 2.3.2 AIV from Indonesia were closed with H5N1 clade 2.3.2 AIV avian influenza viruses from Vietnam, China, Hongkong. The substitution of M2 protein (V27I) was identified in six isolates H5N1 clade 2.3.2 AIV isolated from Indonesia. Avian influenza of clade 2.3.2 H5N1 subtype from Indonesia produced the formation of CPE and the positive HA reaction with non-toxic concentration of amantadine hydrochloride in MDCK cells. The result of genetic analysis of M2 gene for amantadine resistance was related with the results of HA test and the formation of CPE in MDCK cells. These results established that amantadine resistance have been identified in H5N1 clade 2.3.2 AIV viruses isolated from Indonesia

Efficacy, Mechanism and Antiviral Resistance of Neuraminidase Inhibitors and Adamantane against Avian Influenza

Vaccination and antiviral drug are often used to control influenza. However, the effectiveness of vaccine was impaired due to the emergence of new variant of virus strain. Antiviral drug consists of prophylactic and curative substances, namely M2 ion channel inhibitors (adamantane; amantadine and rimantadine) and neuraminidase (NA) inhibitors (NAIs; oseltamivir, zanamivir, peramivir, laninamivir). The synthesis and modification of antiviral neuraminidase (NA) inhibitors (NAIs) and adamantanes increased the antiviral effectiveness. The mechanism of the neuraminidase inhibitor is to prevent influenza infection by inhibiting the release of the virus from internal cells. Adamantane is antiviral drug that selectively inhibits the flow of H+ ions through M2 protein to prevent the uncoating virus particles getting into the endosome. The substitution of (H275Y, S247N, I223L, K150N, R292K, I222T, R152K, R118K, E119V) on NA protein caused resistance of avian influenza virus against the neuraminidase inhibitor. The combination of mutations (S247N, I223L, K150N) increased the resistance of influenza A (H5N1) virus. The diffusion of adamantane resistance varies among HA subtypes, the species of host, the period of isolation, and region. Mutations at residues of 26, 27, 30, 31 or 34 transmembrane M2 protein caused adamantane resistance. The unique substitution (V27I) of M2 protein of clade 2.3.2 H5N1 subtype isolated in Indonesia in 2016 has been contributed to the amantadine resistance. Antiviral combination of M2 ion channel inhibitors and neuraminidase (NA) inhibitors is effective treatments for the resistance.

Viral Factors Associated With the High Mortality Related to Human Infections With Clade 2.1 Influenza A/H5N1 Virus in Indonesia

Background Since their emergence in Indonesia in 2005, 200 human infections with clade 2.1 highly pathogenic avian influenza A/H5N1 virus have been reported, associated with exceptionally high mortality (84%) compared to regions affected by other genetic clades of this virus. To provide potential clues towards understanding this high mortality, detailed clinical virological analyses were performed in specimens from 180 H5N1 patients, representing 90% of all Indonesian patients and 20% of reported H5N1-infected patients globally. Methods H5N1 RNA was quantified in available upper- and lower-respiratory tract specimens as well as fecal and blood samples from 180 patients with confirmed infection between 2005 and 2017. Mutations in the neuraminidase and M2 genes that confer resistance to oseltamivir and adamantanes were assessed. Fatal and nonfatal cases were compared. Results High viral RNA loads in nasal and pharyngeal specimens were associated with fatal outcome. Mortality increased over time during the study period, which correlated with increasing viral RNA loads on admission. Furthermore, the prevalence of amantadine resistance–conferring M2 mutations increased over time, and viral loads were higher in patients infected with viruses that harbored these mutations. Compared to observations from other regions, viral RNA was detected more frequently in feces (80%) and particularly in blood (85%), and antiviral responses to oseltamivir appeared less pronounced. Conclusions These observations confirm the association of viral load with outcome of human H5N1 infections and suggest potential differences in virulence and antiviral responses to oseltamivir that may explain the exceptionally high mortality related to clade 2.1 H5N1 infections in Indonesia.