Isolation, Identification and Characterization of Influenza Viruses from Upper Respiratory Tract Infections CURTI)

Abstract

Acute respiratory infection (ARI) is the major cause of morbidity and mortality throughout the world, especially in young children of developing countries. Majority of the in fections are due to viral pathogens of which most common are influenza-, adeno-, para-influenza- and respiratory syncytial viruses (RSV). To find out the viral etiology in ARI cases in Rawalpindi and Islamabad, 80 samples were collected from patients attending the outdoor clinic of Federal Government Services Hospital (FGSH) and indoor patients of Pakistan Institute of Medical Sciences (PIMS) with not more than three days of cl ini cal history of ARt. ~a e to female ratio was 2: I. Age distribution in children ranged from five weeks to 12 years. Adults/elderly patients ranging in age from 12 to 70 years were also examined for the presence of respiratory viruses. The patients were presenting clin ical symptoms like running ~ nose, cough, strider, headache, fever including bronchitis/bronchiolitis and pneumonia. Few - =-=- . patients were also complaining underlying diseases like asthma, gastroenteritis, and cardiovascular and renal diseases. All the samples were inoculated in Madin-Darby Canine Kidney (MDCK), Secondary Rhesus Monkey Kidney (LLCMK-2) and Human Epithelial Carcinoma (Hep-2) cell lines. Of 80 throat swab specimens, 11 (13.75%) produced hemadsorption in MDCK and LLCMK-2 cel l lines, which on subsequent sero-typing were identified as influenza virus AlH3N2 type. No adeno-, para-influenza- and RSV viruses were isolated. Five of 11 influenza virus isolates were detected from hospitalized patients (children), demonstrating that influenza might be the leading cause of pediatric hospitalization during winter. High titer [256+ Hemagglutination Unit (HAU)] of influenza virus was obtained in MOCK cells than LLCMK-2 cells [128+ HAU] in relatively shorter time «24 hours) in the presence of trypsin. PCR offers an a lternate to culture for influenza detection but it does not characterize influenza antigenic variants. For this constantly evolving and re-emerging pathogen, such characterization is important. Viral cu lture is efficient technique for influenza diagnosis and is the only technique that helps in fu lly characterization of new variants. The study demonstrates that influenza viruses are important pathogens along other respiratory viruses in ARI in rainy and cold seasons. Effective methods of prophylaxis are needed not on ly for high-risk patients but also for hea lthy young children.