Orthomyxoviridae

orthomyxoviridae characteristics

• linear structure

• enveloped

• ONLY RNA VIRUS THAT REPLICATES IN NUCLEUS WEIRD MF

surface antigens of orthomyxoviridae

• H - hemagglutinin

• N - neuraminidase

• continually changing to produce subtypes

which of the influenzas are segmented?

influenza A

flu A causes outbreaks—

annually in cold weather around november to april

seasonal subtypes of flu A

H3 and H1

why is lifelong immunity not possible for flu A?

antigenic changes

antigenic drift

minor changes resulting from point mutation in H and N genes

• annual outbreaks

antigenic shift

major changes resulting from genetic reassortment between strains

• produce worldwide outbreaks of pandemics every 10-20 years

flu B infection timeline

seasonal also

flu B only infects—

humans (and sea lions)

flu B substrains

• victoria

• yamagata

flu B changes seasonally because of—

antigenic drift only