Tanushree Dangi

Viral aetiology of acute lower respiratory tract illness in hospitalised paediatric patients of a tertiary hospital: one year prospective study.

CONTEXT Acute lower respiratory tract infections (ALRI), ranked as the second leading cause of death are the primary cause of hospitalisation in children. Viruses are the most important causative agents of ALRI. AIM To study the viral aetiology of ALRI in children at a tertiary care hospital. SETTING AND DESIGN One year prospective observational study in a tertiary care hospital of King Georges Medical University, Lucknow. MATERIAL AND METHODS Nasopharyngeal aspirate (NPA) was collected from children admitted with signs and symptoms of ALRI who were aged 0-14 years. Samples were transported to the laboratory at 4°C in viral transport media and processed for detection of respiratory syncytial virus (RSV) A and B, influenza virus A and B, adenovirus (ADV), human Boca virus (HBoV), human metapneumo virus (hMPV) and parainfluenzavirus 1, 2, 3 and 4 using mono/multiplex real-time polymerase chain reaction (RT-PCR). STATA was used for statistical analysis. RESULTS In one year, 188 NPAs were screened for respiratory viruses, of which 45.7% tested positive. RSV was most commonly detected with 21.3% positivity followed by measles virus (8.5%), influenza A virus (7.4%), ADV (5.3%), influenza B virus (1.6%), hMPV (1.1%) and HBoV (0.5%). Month wise maximum positivity was seen in December and January. Positivity rate of RSV was highest in children aged < 1 year, which decreased with increase in age, while positive rate of influenza virus increased with increasing age. CONCLUSION The occurrence of viral predominance in ALRI is highlighted.

High prevalence of human metapneumovirus subtype B in cases presenting as severe acute respiratory illness: an experience at tertiary care hospital

A comparatively newly discovered human metapneumovirus (HMPV) has emerged as an important cause of severe acute respiratory illness (SARI), second only to respiratory syncytial virus (RSV). RSV and HMPV taxonomically belong to same family and subfamily, and their clinical presentation and seasonal distribution are also seemed to be indistinguishable. Present study was planned to know the epidemiology and prevalence of HMPV and RSV in patients presented as SARI in a tertiary care hospital.

Hospital outbreak of human respiratory syncytial virus (HRSV) illness in immunocompromised hospitalized children during summer.

The human respiratory syncytial virus (HRSV) is a community‐acquired virus that mainly causes acute respiratory tract infection in infants and children. HRSV is increasingly recognized as an important nosocomial pathogen causing morbidity in immunocompromised patients. Here, we are reporting a hospital outbreak of HRSV during summer in children receiving chemotherapy for haematological malignancies. Prompt detection and timely preventive measures could abort the devastating outbreak.

Molecular characterization of circulating pandemic strains of influenza A virus during 2012 to 2013 in Lucknow (India).

The pandemic H1N1 strain of Influenza A virus [A(H1N1)pdm09] is now well adapted in human populations. However, it is still causing sporadic outbreaks worldwide with different severity. The present study was planned to understand the genetic diversity (based on the HA1 gene) of influenza A(H1N1)pdm09 strains circulating during the post pandemic period. The HA1 gene was selected because the HA1 protein is immunogenic, functions as a receptor binding site and indirectly affects transmission and pathogenicity of virus. A total of 2,818 cases were enrolled. Nasal/throat swabs from all cases were tested by one‐step real time PCR for detection of influenza virus types and subtypes according to the CDC protocol. Of these, 134 cases were A(H1N1)pdm09 positive, 34 of which were screened for HA1 gene (position 434–905) sequencing (Big‐Dye terminator using 3130 ABI, Genetic analyzer). Molecular and phylogenetic analysis was performed using PhyML approach (v. 3.0). All A(H1N1)pdm09 positive and negative cases were clinically characterized. Phylogentically, all Lucknow strains (n = 33) except one fall with the clade seven reference strain. One strain showed 99.9% similarities with clade one reference strain A/California/07/2009. In mutational analysis, 33 strains had the S220T mutation, which is at an antigenic site and characteristic of clade seven along with few minor mutations; K180I/T/Q, V190I, S200P, S202T, A203T, A214T, S220T, V251I, and A273T. These results suggest that clade seven was the most widely circulating clade in Lucknow and A(H1N1)pdm09 cases showed mild clinical symptoms as compared to A(H3N2) or influenza B cases. J. Med. Virol. 86:2134–2141, 2014.

Influenza Virus: A Brief Overview

Influenza is a major public health concern, infecting 5–15% of the global population annually. Influenza virus belongs to family Orthomyxoviridae, and has three types A, B and C. Infection by influenza virus A is most common and severe, generally found in humans. It spreads rapidly and affects human population across large geographical region within short period of time with varying degree of pathology from mild to severe. Wild aquatic birds and other animal species like birds, pigs, ferret, horses, seals, whales, mink, giant anteaters, cats and dogs are the reservoir for the influenza A virus. Influenza B and C viruses have very limited host range and appear predominantly in humans. Influenza virus gains pandemic potential through genetic reassortment called “genetic shift” with complete renewal of surface antigen and a small but gradual genetic change by mutations which make it to adapt efficiently in human population called “genetic drift”. Although, the epidemiology related to influenza infection has been studied from several years but some facts associated to disease transmission has poorly understood. This article reviews the important aspects of virological, epidemiological and clinical features related to influenza virus for better understanding of disease transmission and its pathogenesis.

Genetic changes in influenza A(H3N2) viruses circulating during 2011 to 2013 in northern India (Lucknow).

Genetic variability in the hemagglutinin (HA1) and the neuraminidase (NA) genes of influenza viruses results in the emergence of new strains which differ in pathogenicity and severity. The present study was undertaken for genotypic characterization of the HA1 and NA genes of the influenza A(H3N2) strains, detected during the 2011–2013. A total of fifty five influenza A(H3N2) positive samples [2011 (n = 20), 2012 (n = 4) and 2013 (n = 31)] were studied. The 824 bp segment of HA1 gene and 931 bp segment of NA gene were amplified and sequenced by Big‐Dye terminator kit on ABI3130, Genetic analyzer. Molecular and phylogenetic analysis was done by MEGA 5.05 software and PhyML program (v3.0). Mutations were determined by comparing the deduced amino acid sequences of study strains with that of 2009–2013 vaccine strains. The studied influenza A(H3N2) strains showed 98.1–99.6% similarity in HA1 and NA amino acid sequences with the influenza A/Victoria/361/2011 vaccine strain. Four mutations in the HA1 amino acid sequences (T128A, R142G, L157S and N278K) and three unique mutations in the NA amino acid sequences [D251V, S315G and V313A] were found. These mutations were observed only in strains from the year 2013 (cluster II). None of the strains showed the presence of mutations, N294S and R292K, markers of oseltamivir resistance. In conclusion, Lucknow strains have accumulated the significant number of mutations in the antigenic sites of the HA and the NA coding sequences and continue to be evolving from the 2013 vaccine strain [A/Victoria/361/2011], however, mutations specific for oseltamivir resistance were not detected. J. Med. Virol. 87:1268–1275, 2015.