#Replacement of #NAIs susceptible #influenza A(#H1N1) with #resistant phenotype in 2008 and circulation of susceptible influenza A and B viruses during 2009-2013, #ZA (Influenza Other Respir Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Influenza Other Respir Viruses. 2018 Sep 14. doi: 10.1111/irv.12611. [Epub ahead of print]

Replacement of neuraminidase inhibitor susceptible influenza A(H1N1) with resistant phenotype in 2008 and circulation of susceptible influenza A and B viruses during 2009-2013, South Africa.

Treurnicht FK1, Buys A1, Tempia S2,3, Seleka M1, Cohen AL2,4, Walaza S1,5, Glass AJ6, Rossouw I7, McAnerney J1, Blumberg L8,5, Cohen C1,5, Venter M9,10.

Author information:  1 Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa. 2 Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. 3 Influenza Program, Centers for Disease Control and Prevention, Pretoria, South Africa. 4 Global Immunization Monitoring and Surveillance, Expanded Programme on Immunization, Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland. 5 School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. 6 Department of Molecular Pathology, Lancet Laboratories, Johannesburg, South Africa. 7 PathCare Laboratories, PathCare Park, N1 City, Cape Town, South Africa. 8 Division of Public Health Surveillance and Response, National Institute of Communicable Diseases, Sandringham, Johannesburg, South Africa. 9 Emerging Arbo-and Respiratory virus Program, Department of Medical Virology, University of Pretoria, Pretoria, South Africa. 10 Tshwane Academic Division, National Health Laboratory Service, Pretoria, South Africa.




Data on the susceptibility of influenza viruses from South Africa to neuraminidase inhibitors (NAIs) is scarce, and no extensive analysis was done.


We aimed to determine oseltamivir and zanamivir susceptibility of influenza A and B virus neuraminidases (NAs), 2007-2013, South Africa.


We enrolled participants through national influenza-like illness surveillance, 2007-2013. Influenza diagnosis was by virus isolation and real-time polymerase chain reaction (qPCR). Drug susceptibility was determined by chemilluminescence-based NA-STAR/NA-XTD assay. Sanger sequencing was used to determine molecular markers of NAI resistance.


Forty percent (6,341/15,985) of participants were positive for influenza viruses using virus isolation (2007-2009) and qPCR (2009-2013) methods. 1,236/6,341 (19.5%) virus isolates were generated of which 307/1,236 (25%) were tested for drug susceptibility. During 2007-2008 the median 50% inhibitory concentration (IC50 ) of oseltamivir for seasonal influenza A(H1N1) increased from of 0.08 nM (range 0.01-3.60) in 2007 to 73 nM (range 1.56-305 nM) in 2008. Influenza A isolates from 2009-2013 were susceptible to oseltamivir [A(H3N2) median IC50 = 0.05 nM (range 0.01-0.08); A(H1N1)pdm09= 0.11 nM (range 0.01-0.78)] and zanamivir [A(H3N2) median IC50 = 0.56 nM (range 0.47-0.66); A(H1N1)pdm09= 0.35 nM (range 0.27-0.533)]. Influenza B viruses were susceptible to both NAIs. NAI resistance-associated substitutions H275Y, E119V, and R150K (N1 numbering) were not detected in influenza A viruses that circulated in 2009-2013.


We confirm replacement of NAI susceptible by resistant phenotype influenza A(H1N1) in 2008. Influenza A and B viruses (2009-2013) remained susceptible to NAIs; therefore these drugs are useful for treating influenza-infected patients.

This article is protected by copyright. All rights reserved.

KEYWORDS: South Africa; influenza; oseltamivir; susceptibility

PMID: 30218485 DOI: 10.1111/irv.12611

Keywords: Seasonal Influenza; H1N1; H1N1pdm09; H3N2; Influenza B; Antivirals; Drugs Resistance; South Africa; Oseltamivir.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.