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. 2014;25(3):372-5.
doi: 10.1007/s13337-013-0190-8. Epub 2014 Jan 19.

Characterization of influenza virus among influenza like illness cases in Mumbai, India

Soumen Roy  1 , Ritwik Dahake  1 , Deepak Patil  1 , Shweta Tawde  1 , Sandeepan Mukherjee  1 , Shrikant Athlekar  1 , Abhay Chowdhary  1 , Ranjana Deshmukh  1
Affiliations

Characterization of influenza virus among influenza like illness cases in Mumbai, India

Soumen Roy et al. Virusdisease. 2014.

Abstract

The present study was carried out to monitor influenza viruses by identifying the virus and studying the seasonal variation during 2007-2009 in Mumbai. A total of 193 clinical respiratory samples (nasal and throat swab) were collected from patients having influenza like illness in Mumbai region. One-step real-time reverse-transcriptase PCR (rRTPCR) was used to detect Influenza type A (H1 and H3) and Influenza type B virus. Isolation of the virus was carried out using in vitro system which was further confirmed and typed by hemagglutination assay and hemagglutination inhibition assay. Out of 193 samples 24 (12.4 3%) samples tested positive for influenza virus, of which 13 (6.73 %) were influenza type A virus and 10 (5.18 %) were influenza type B virus, while 1 sample (0.51 %) was positive for both. By culture methods, 3 (1.55 %) viral isolates were obtained. All the three isolates were found to be Influenza type B/Malaysia (Victoria lineage) by Hemagglutination Inhibition Assay. The data generated from the present study reveals that both Influenza type A and B are prevalent in Mumbai with considerable activity. The peak activity was observed during monsoon season.

Keywords: ILI cases; Influenza virus; Phylogeny; rRT PCR.

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Figures

Fig. 1
Fig. 1
a Percent positivity of influenza A/H1 (2.59 %), A/H3 (4.66 %) and influenza B (5.70 %) virus by rRT-PCR and culture methods (1.55 %); b Percent positivity of influenza samples within each age group; c Year-wise distribution of samples with respect to viral subtype positivity for the years 2007, 2008 and 2009
Fig. 2
Fig. 2
Phylogenetic tree of influenza virus strains (Mumbai isolates, related strains and reference strains) using the HA gene sequences The evolutionary history was inferred using the Neighbor-Joining method. The evolutionary distances were computed using the Kimura 2-parameter method with the percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (500 replicates) shown next to the branches. The tree was rooted with a non-related influenza strain (H5N1). Evolutionary analyses were conducted in MEGA 5. Black squares indicate the relatedness of Mumbai isolates with the vaccine component of 2009–2010; open circles indicate influenza A strains
See this image and copyright information in PMC

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