Prescription – Pollution – Poo – Pandemics - Priorities : Neuraminidase Inhibitors from an Environmental Resistance Development Perspective

The natural Influenza A virus (IAV) host is waterfowl. Human IAV is treated with neuraminidase inhibitors (NAIs), which are stockpiled worldwide in case of an IAV pandemic. As the drugs escape regular waste water treatment, they can be detected in river waters. We hypothesize that exposure of low pathogenic avian IAV (LPAIV) infecting Mallards to NAIs in the water promotes development of resistance that can persist in the absence of drugs. Dissemination of resistance genes to humans pose a health risk, particularly if incorporated into a pandemic IAV. To test the hypothesis, LPAIVs of both NA phylogenetic groups were assessed in an in vivo Mallard model by inoculation and exposure of birds to NAI in their water. In previous work in the model, the oseltamivir-resistant H275Y mutation emerged in H1N1 in response to oseltamivir exposure and persisted without drug pressure. In this thesis, a H7N9 was exposed to oseltamivir and a H1N1 and H4N2 to zanamivir and peramivir. Furthermore, a H1N1 with the H275Y mutation was exposed to zanamivir in order to assess the additional development of zanamivir resistance and the persistence of the H275Y mutation in the presence of zanamivir. Several substitutions reducing drug susceptibility emerged; I222T in H7N9, V116A, A138V, T157I, R152K and D199G in H1N1 exposed to zanamivir, H275N and E119G in H4N2 exposed to zanamivir and 275Y in H4N2 exposed to peramivir. None of the tested zanamivir-induced substitutions persisted in the absence of drug, indicating lower risk of circulation of these substitutions in the wild as compared to oseltamivir. There is a risk of NAI resistance emerging in LPAIVs of Mallards exposed to NAIs in the water. Zanamivir appears to be the best option from an environmental perspective. Drug concentrations in the Mallard model are mostly higher than the concentrations detected in rivers, but are in the same magnitude regarding OC and an H1N1 LPAIV. Given the importance of NAIs as the first line of defence in the event of a pandemic, this is of public health concern. Surveillance of LPAIV in waterfowl, prudent use of NAIs and waste water treatment improvements are important measures to mitigate the risk