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. 2016 Nov 4;11(11):e0166336. doi: 10.1371/journal.pone.0166336

Fig 4. Intramuscular immunization with live EV-D68 strains induces virus-specific homologous NA titers.

Fig 4

(A) Female cotton rats were immunized i.m. with 106 TCID50/100 μl of indicated virus on day 0 and boosted 3 weeks after the first immunization. Serum samples were obtained at 3 week (before boosting) and 7 weeks after the first immunization and homologous serum NA titers were determined. The sera were assayed in duplicate and NA titer is expressed as Log2 geometric mean ± SE. n = 10–15 from two independent experiments, ***p< 0.001 for 3 weeks NA titer compared with 7 weeks NA. (B) Passive transfer of VANBT immune sera protects animals from VANBT challenge. Animals were treated intraperitoneally with 0.5 ml 1 x PBS (mock) or serum from animals immunized i.m. with either UV-VANBT, VANBT, or MO/49. The following day, animals were challenged i.n. with 106 TCID50 of VANBT and euthanized 10 h later to determine nose and lung viral titers. n = 4–5 per group. * p<0.05 for each group compared with mock group.