Detection of Influenza C Virus Infection among Hospitalized Patients, Cameroon

We report 3 cases of influenza C virus in children hospitalized with severe acute respiratory infection in Cameroon. Two of these case-patients had grave clinical manifestations, but all 3 recovered. The lack of specific antiviral drugs for influenza C virus highlights the need to identify and describe cases involving this virus

The characteristics and antigenic properties of recently emerged subclade 3C.3a and 3C.2a human influenza A(H3N2) viruses passaged in MDCK cells

Fil: Lin, Yipu. The Francis Crick Institute, London; Reino Unido.Fil: Wharton, Stephen A. The Francis Crick Institute, London; Reino Unido.Fil: Whittaker, Lynne. The Francis Crick Institute, London; Reino Unido.Fil: Dai, Mian. The Francis Crick Institute, London; Reino Unido.Fil: Ermetal, Burcu. The Francis Crick Institute, London; Reino Unido.Fil: Lo, Janice. Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region; China.Fil: Pontoriero, Andrea. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Baumeister, Elsa. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas; Argentina.Fil: Daniels, Rodney S. The Francis Crick Institute, London; Reino Unido.Fil: McCauley, John W. The Francis Crick Institute, London; Reino Unido.Two new subclades of influenza A(H3N2) viruses became prominent during the 2014-2015 Northern Hemisphere influenza season. The HA glycoproteins of these viruses showed sequence changes previously associated with alterations in receptor-binding properties. To address how these changes influence virus propagation, viruses were isolated and propagated in conventional MDCK cells and MDCK-SIAT1 cells, cells with enhanced expression of the human receptor for the virus, and analysed at each passage

Association of Increased Receptor-Binding Avidity of Influenza A(H9N2) Viruses with Escape from Antibody-Based Immunity and Enhanced Zoonotic Potential

We characterized 55 influenza A(H9N2) viruses isolated in Pakistan during 2014–2016 and found that the hemagglutinin gene is of the G1 lineage and that internal genes have differentiated into a variety of novel genotypes. Some isolates had up to 4-fold reduction in hemagglutination inhibition titers compared with older viruses. Viruses with hemagglutinin A180T/V substitutions conveyed this antigenic diversity and also caused up to 3,500-fold greater binding to avian-like and >20-fold greater binding to human-like sialic acid receptor analogs. This enhanced binding avidity led to reduced virus replication in primary and continuous cell culture. We confirmed that altered receptor-binding avidity of H9N2 viruses, including enhanced binding to human-like receptors, results in antigenic variation in avian influenza viruses. Consequently, current vaccine formulations might not induce adequate protective immunity in poultry, and emergence of isolates with marked avidity for human-like receptors increases the zoonotic risk

Overview of three influenza seasons in Georgia, 2014–2017

<div><p>Background</p><p>Influenza epidemiological and virologic data from Georgia are limited. We aimed to present Influenza Like Illness (ILI) and Severe Acute Respiratory Infection (SARI) surveillance data and characterize influenza viruses circulating in the country over three influenza seasons.</p><p>Methods</p><p>We analyzed sentinel site ILI and SARI data for the 2014–2017 seasons in Georgia. Patients’ samples were screened by real-time RT-PCR and influenza viruses isolated were characterized antigenically by haemagglutination inhibition assay and genetically by sequencing of HA and NA genes.</p><p>Results</p><p>32% (397/1248) of ILI and 29% (581/1997) of SARI patients tested were positive for influenza viruses. In 2014–2015 the median week of influenza detection was week 7/2015 with B/Yamagata lineage viruses dominating (79%); in 2015–2016—week 5/2016 was the median with A/H1N1pdm09 viruses prevailing (83%); and in 2016–2017 a bimodal distribution of influenza activity was observed—the first wave was caused by A/H3N2 (55%) with median week 51/2016 and the second by B/Victoria lineage viruses (45%) with median week 9/2017. For ILI, influenza virus detection was highest in children aged 5–14 years while for SARI patients most were aged >15 years and 27 (4.6%) of 581 SARI cases died during the three seasons. Persons aged 30–64 years had the highest risk of fatal outcome, notably those infected with A/H1N1pdm09 (OR 11.41, CI 3.94–33.04, p<0.001). A/H1N1pdm09 viruses analyzed by gene sequencing fell into genetic groups 6B and 6B.1; A/H3N2 viruses belonged to genetic subclades 3C.3b, 3C.3a, 3C.2a and 3C.2a1; B/Yamagata lineage viruses were of clade 3 and B/Victoria lineage viruses fell in clade1A.</p><p>Conclusion</p><p>In Georgia influenza virus activity occurred mainly from December through March in all seasons, with varying peak weeks and predominating viruses. Around one third of ILI/ SARI cases were associated with influenza caused by antigenically and genetically distinct influenza viruses over the course of the three seasons.</p></div

Referral of ILI cases to outpatient clinic vs laboratory-confirmed influenza detections by week, 2014–2017, Georgia.

<p>Vertical bars represent numbers of influenza positive samples among ILI cases each week over three consecutive seasons. The blue line shows weekly referrals of ILI cases to the outpatient clinic per 100 000 population.</p

Admission of SARI cases to hospitals vs laboratory-confirmed influenza detections by week, 2014–2017, Georgia.

<p>Vertical bars show numbers of influenza positive specimens among SARI cases each week. The blue line represents percentages of influenza-positive cases among total SARI hospital admissions on a weekly basis.</p

HA gene phylogeny of influenza A/H3N2 viruses detected in Georgia during three influenza seasons 2014–2017.

<p>Vaccine viruses are indicated in red; 2014–2015, 2015–2016 and 2016–2017 viruses from Georgia in blue, pink and brown respectively. Reference and vaccine viruses against which post-infection ferret antisera were raised for use in HI assays are in bold type. The scale bar represents nucleotide substitutions per site.</p

Age distribution of influenza confirmed ILI and SARI cases, 2014–2017 seasons, Georgia.

<p>Age distribution of influenza confirmed ILI and SARI cases, 2014–2017 seasons, Georgia.</p