Development of a live attenuated trivalent porcine rotavirus A vaccine against disease caused by recent strains most prevalent in South Korea

Figures

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  Figure 1. Electropherogram (PAGE) of selected passages in MA104 cells of three porcine RVA strains. The RNA genomic segments of three vaccine strains from different passage numbers were separated by PAGE and visualized using silver staining. The original virulent strains and each passage of 174-1 (A), K71 (B), and PRG942 (C) demonstrated typical RVA’s RNA segment patterns of 4-2-3-2 and maintained their own patterns throughout the serial passages. Lane 1, original virulent strain; lane 2, 10th passage; lane 3, 20th passage; lane 4, 40th passage; lane 5, 60th passage; lane 6, 80th passage.

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  Figure 2. Histopathological changes in piglets infected with each virulent RVA strain or after challenge following immunization. (A, E, I) Duodenum, jejunum, and ileum of mock-inoculated piglets showed villi of normal length and no crypt hyperplasia. (B–D, F–H, and J–L) Duodenum (B–D), jejunum (F–H), and ileum (J–L) sampled at 7 dpi from piglets inoculated with virulent strains 174-1, PRG942, or K71 showed severe villous atrophy, moderate crypt hyperplasia, and severe lymphoid cell infiltrations in the lamina propria. (M–X) Duodenum (M–P), jejunum (Q–T), and ileum (U–X) sampled at 28 dpv from piglets first immunized with one of the live attenuated monovalent or trivalent vaccines and then challenged with the corresponding original virulent strain(s) 174-1, K71 or PRG942 showed villi of normal length, mild crypt hyperplasia, and mild infiltrations of lymphoid cells in the lamina propria in a manner similar to that of the mock-inoculated group. Hematoxylin and eosin stain. Bars = 200 μm.

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  Figure 3. Serum neutralizing antibody titers in response to the monovalent or trivalent porcine rotavirus vaccination. A Serum samples obtained weekly from piglets immunized with monovalent 174-1V-80, PRG942V-80, or K71V80 vaccines and challenged by exposure with the corresponding virulent strain at 2 weeks post-vaccination. B Serum samples obtained weekly from piglets immunized with a trivalent porcine live attenuated rotavirus vaccine and challenged by exposure with its virulent strain 174-1 at 2 weeks post-vaccination. Serum neutralizing antibody titers were calculated as the geometric mean titers for each group (n = 5 per group).

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  Figure 4. Serum and fecal RV-specific IgM, IgG, and IgA antibody titers determined by ELISA. A, B Serum and fecal samples obtained weekly from piglets immunized with a live attenuated strain 174-1V-80 and challenged by exposure with its virulent strain 174-1 at 2 weeks post-vaccination. C, D Serum and fecal samples obtained weekly from piglets immunized with a live attenuated strain PRG942V-80 and challenged by exposure with its virulent strain PRG942 at 2 weeks post-vaccination. E, F Serum and fecal samples obtained weekly from piglets immunized with a live attenuated strain K71V-80 and challenged by exposure with its virulent strain K71 at 2 weeks post-vaccination. G, H Serum and fecal samples obtained weekly from piglets immunized with a live attenuated trivalent vaccine containing live attenuated strains 174-1V-80, PRG942V-80, and K71V-80 and challenged by exposure with its virulent strains 174-1, PRG942, and K71 at 2 weeks post-vaccination. Antibody titers are expressed as the geometric mean titers (GMTs) for each group (n = 5 piglets per each group).