To describe the unique characteristics of each viral group, including structure and mode of replication.
Mode of replication
Type A – 8 seg. ssRNA
Type B – 8 seg. Type C – 8 seg.
Nucleoprotein covers RNA to form ribonucleoprotein complex, surrounded by matrix, envelope contains hemagglutinin and neuraminidase glycoprotein spikes, pleomorphic
Adsorption mediated by H, uncoating in the cytoplasm, replicates in the nucleus, nucleocapsid assembles, and virus buds through nuclear membrane where matrix has accumulated.
4 stable serotypes - single-stranded (-) RNA, nucleoprotein covers RNA, M protein surrounds nucleoprotein complex, envelope contains attachment protein that has both H and N and the fusion protein (F), pleomorphic
Replication occurs in the cytoplasm, replicates like (-) RNA virus, and buds through cytoplasmic membrane.
30,000 deaths per year in US, incubation 1-2 days, abrupt onset of fever, myalgia, headache, muscle ache, chills, cough and fatigue (5-7 days), followed by prolonged cough (2+ weeks), possible pneumonia (risk factors – age, heart, and lung defects)
Clinical picture, isolate virus in cell culture and serology (antibody titer to H)
Treatment: supportive; Amantadine and Riamantadine (early), new drugs Zanamivir and Oseltamivir (+ for prophylaxis)