During the 2007-2008 influenza season global strain surveillance for antiviral resistance revealed the sudden emergence of oseltamivir resistance in influenza A H1N1 isolates. Although oseltamivir resistance rates vary from region to region, 16% of isolates tested globally were found to be oseltamivir resistant by a histidine to tyrosine mutation of residue 275 of the neuraminidase gene of influenza A. In order to implement effective resistance testing locally a novel real-time reverse-transcriptase PCR (RT-PCR) assay was developed for the detection of the H275Y mutation. To evaluate this method, 40 oseltamivir resistant and 61 oseltamivir sensitive H1N1 influenza isolates were tested using Sanger sequencing, which is the reference method for detection of resistance, pyrosequencing and the novel H275Y RT-PCR assay. In comparison to Sanger sequencing, the sensitivity and specificity of the H275Y RT-PCR assay were 100% (40/40) and 100% (61/61) respectively, while the sensitivity and specificity of pyrosequencing were 100% (40/40) and 97.5% (60/61) respectively. Although all three methods were effective in detecting the H275Y mutation associated with oseltamivir resistance, the H275Y RT-PCR assay was the most rapid and could easily be incorporated into an influenza subtyping protocol.

e The H275Y oseltamivir resistance mutation confers high-level resistance to oseltamivir in isolates of human A(H1N1) influenza. We report the recovery and identification of an influenza B virus with the H273Y neuraminidase point mutation directly from a human patient. The H273Y influenza B isolate is resistant to oseltamivir and peramivir but sensitive to zanamivir.

BackgroundIn early 2017 an outbreak of Mumps virus affected over 100 individuals in the province of Ontario, concurrent with multiple mumps virus outbreaks across North America. Traditional genotyping of mumps outbreaks relies on sequencing a portion of the small hydrophobic (SH) gene, but has limited capability to distinguish between strains of the same genotype. Most mumps cases in Ontario in recent years are of genotype G. We used a novel whole genome sequencing (WGS) protocol to perform a molecular epidemiological investigation of the outbreak.MethodsThroat (n = 5) and buccal (n = 15) swabs positive by RT-PCR for SH or Fusion (F) gene targets were cultured in primary Rhesus monkey kidney cells. Cell free viral extract underwent RT-PCR and subsequent PCR amplification using overlapping primer pairs to cover the entire 15 kilobase (kb) genome. The first 8 samples were amplified with 18 pairs of overlapping primers, which was reduced to 9 sets (average fragment size 1.9 kb, range 1.6–2.8 kb) for the final 12 samples. Mumps cDNA libraries were prepared with Nextera XT kit and WGS of the indexed fragments was performed with V2 reagent kits on the Illumina MiSeq instrument. Reference based genome assembly was performed using samtools version 1.4. Phylogenetic analysis was performed by maximum likelihood method in MEGA7.ResultsWe identified two distinct genotype G lineages comprised of 9 patients each and closely related to a 2009–2010 outbreak in Ontario and New York (Figure 1). Inter-lineage single nucleotide polymorphism (SNP) differences ranged from 25 to 31, whereas intra-lineage SNPs ranged from 0 to 8 SNPs. Two outlying sequences, of genotype C and G respectively, may represent sporadic introduction of virus from other areas. Time from virus isolation to SNP based analysis was approximately 4 days.ConclusionWGS of Mumps virus culture isolates using the PCR fragment method identified two distinct genotype G lineages in a large provincial outbreak. This method may aid public health authorities identify separate transmission chains in the case of large outbreaks.Disclosures All authors: No reported disclosures.