Several strains of wild-type influenza A virus were studied in the ferret tracheal organ culture system. Ciliary activity and viral replication were measured. Ciliary activity was reduced more rapidly by A/Hong Kong/45/68 (H3N2) (A/HK) and A/Victoria/3/75 (H3N2) (A/Vic) than by A/New Jersey/8/76 (Hsw1N1) (A/NJ), A/Scotland/840/74(3HN2) (A/Scot), or A/USSR/90/77 (H1N1) (A/USSR). A/HK, A/Vic, and A/Scot produced titers of virus higher than A/USSR or A/NJ during the first three days after infection. Differences in effects of the five viruses on cilia were not related to history of egg passage. The two strains that destroyed ciliary activity rapidly had caused excess mortality in the United States, whereas the three that destroyed ciliary activity more slowly had not. A relationship may exist between the properties contributing to virulence in humans and the destruction of ciliary activity in vitro in this culture system.

Animals↗

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Partnerships for detecting emerging infectious diseases: Nepal and global influenza surveillance.

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Global Health↗

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Molecular and epidemiologic analysis of dengue virus isolates from Somalia.

Nucleotide sequence analysis was performed on 14 dengue virus isolates (13 dengue-2 viruses and 1 dengue-3 virus) recovered from febrile soldiers in Somalia in 1993. The dengue-2 viruses were most closely related to dengue-2 virus recovered in Somalia in 1984. However, differences in nucleotide sequence (0.35% to 1.35%) were evident among the 1993 isolates. These differences were closely associated with the geographic location of the infection as well as with different times of infection at the same location. Genetic difference between strains was not associated with differences in clinical features. Molecular analysis of dengue viruses is a useful adjunct to epidemiologic investigation of their distribution over distance and time.

Adult↗