Emerging Influenza Strains in the Last Two Decades: A Threat of a New Pandemic?

Abstract

In the last 20 years, novel non-seasonal influenza viruses have emerged, most of which have originated from birds. Despite their apparent inability to cause pandemics, with the exception of H1N1 swine influenza virus, these viruses still constitute a constant threat to public health. While general concern has decreased after the peak of the H5N1 virus, in recent years several novel reassorted influenza viruses (e.g., H7N9, H9N2, H10N8) have jumped the host-species barrier and are under surveillance by the scientific community and public health systems. It is still unclear whether these viruses can actually cause pandemics or just isolated episodes. The purpose of this review is to provide an overview of old and novel potential pandemic strains of recent decades.

The Virome of the Human Respiratory Tract

“…Since the discovery of severe acute respiratory syndrome coronavirus in 2003, 19 other novel respiratory pathogens have emerged, including coronaviruses NL63, HKU1, and MERS (reviewed in 20 ) and influenza viruses H1N1 pandemic strain and H7N9. 21 In each case, the molecular tools to adequately survey the spread of the virus had to be developed. Once assays become available, the transmission of these viruses can be tracked and recommendations for protecting public health can be made.…”

Emerging infectious diseases: Focus on infection control issues for novel coronaviruses (Severe Acute Respiratory Syndrome-CoV and Middle East Respiratory Syndrome-CoV), hemorrhagic fever viruses (Lassa and Ebola), and highly pathogenic avian influenza viruses, A(H5N1) and A(H7N9)

“…Multiple subtypes of influenza A of avian origin have been reported to cause human disease in recent years, including H5N1, H6N1, H7N2, H7N3, H7N7, H7N9, H9N2, H10N7, and H10N8. 105,[108][109][110][111] Of these, H5N1, H7N2, and H7N3 have been responsible for human infections in North America.…”

Adjuvant formulations for virus-like particle (VLP) based vaccines

“…In addition, VLP production can be achieved using current good manufacture practices (cGMP) without the need for the biological safety containment that is typically required for a live virus vaccine production process [33]. In the case of influenza, for example, new virus strains emerge due to the accumulation of mutations, (antigenic drift) [34] or by genetic reassortment, (antigenic shift) [35] resulting in epidemic outbreaks of recurring frequency and unpredictable intervals. Influenza vaccine manufacturing using the classical embryonated chicken egg system to produce either live-attenuated or split virus vaccines requires a minimum of 6 months for seed selection, optimization, and large-scale vaccine production.…”