Evaluation of PRRSv specific, maternally derived and induced immune response in Ingelvac PRRSFLEX EU vaccinated piglets in the presence of maternally transferred immunity

Figures

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  Fig 1. a) Graphical scheme of the experimental study design. b) PRSSv-specific antibody levels in piglets over time. Sera from piglets were analyzed on a weekly basis for PRRSSV-specific antibodies by Idexx-Herd check X3 ELISA. Single values were calculated as sample to positive control ratio (S/P) and were depicted as mean values within the groups (no vaccination group, 2-wks vaccination group, 3-wks vaccination group). The first samples in week 0 were taken after colostrum intake. Significant differences were calculated by Mann-Whitney-test and were indicated in the graph. Significant differences of ****p ≥ 0.0001 at 9 weeks between no vaccination group vs. 2-wks and 3-wks vaccination group; **p = 0.0036 at 10 weeks between no vaccination group vs. 2-wks and 3-wks vaccination group; ****p ≥ 0.0001 at 12 weeks between no vaccination group vs. 2-wks and 3-wks vaccination group and *p = 0,0426 at 12 weeks between 2-wks vs. 3-wks vaccination group.

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  Fig 2. Lung lesion score. Lungs were analyzed 10 days after PRRSv-challenge at necropsy for PRRSv-specific lesions. Data are displayed as mean values (% of affected lung tissue) with SEM within the groups (no vaccination group, 2-wks vaccination group, 3-wks vaccination group). Significant differences were calculated by Mann-Whitney-test and calculated p-values were indicated in the graph.

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  Fig 3. PRRSv-specifc IgG and IgA level in sows and piglets. a) Serum from sows was collected at the day of farrowing (day 0) and was analyzed for PRRSV-specific IgG and IgA levels. b) Colostrum and milk at the indicated time points (day 0 and day 1) after farrowing were collected and analyzed for PRRSv-specific IgG and IgA levels. Serum from piglets was taken at day 0, 14 and 21 and was analyzed for PRRSv-specific IgG (c) and IgA (d) levels.

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  Fig 4. Cellular immunity in colostrum and milk. Cells were isolated from milk and colostrum and recalculated cell counts / ml were shown in a). b) Isolated cells from milk and colostrum were assessed for a PRRSv-specific IFNγ response by ELISpot. IFNγ spot forming units of milk and colostrum derived cells were stimulated either with medium or PRRSv virus (MOI 1.0). Each symbol represents the average spot forming units of 3 technical replicates for PRRS virus stimulation subtracted from the average of 2 technical replicates for medium stimulation, both performed on one sample from one individual animal. Samples of milk and colostrum from the same animal were connected with lines.

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  Fig 5. PRRSv-specific IFNγ response of PBMCs from 1- and 2-weeks old piglets. PBMCs derived from 1 week (a) and 2 week (b) old piglets were stimulated with medium and PRRS virus (MOI of 1.0) to determine the antigen-specific IFNγ response by ELISpot. Each symbol represents the average spot forming units of 3 technical replicates for PRRS virus stimulation and 2 technical replicates for medium stimulation, both performed on one sample from one individual animal. The horizontal bars represent the median spot forming units of 30 animals.

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  Fig 6. PRRSv-specific IFNγ response before and after challenge. Spot forming units of 1x106 porcine PBMCs stimulated with RPMI medium (circles) or PRRS virus (squares, MOI of 1.0) were determined before PRRS virus challenge (a) and 10 days after PRRS virus challenge (b) by IFNγ ELISpot. c) Comparison of PRRSv (MOI 1) restimulated PBMCs before and after challenge for all three groups. Each symbol represents the average IFNγ-specific spot forming units of 3 technical replicates for PRRS virus stimulation and 2 technical replicates for RPMI medium stimulation, both performed on one sample from one individual animal. The horizontal bars represent the median spot forming units. Significant differences were calculated by Mann-Whitney-test and calculated p-values were indicated in the graph.

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  Fig 7. PRRSv-specific antibody response before and after challenge. a) PRRSv-specific IgG and (b) IgA response were assessed by PRRSv-specific ELISA at the indicated time points. Each symbol represents the calculated average of one animal. Significant differences were calculated by Mann-Whitney-test and calculated p-values were indicated in the graph.

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  Fig 8. Pro-inflammatory cytokine response 10 days after PRRS virus challenge from BALF. 10 days after PRRS virus challenge BALF were taken at necropsy. Concentrations of the cytokines IL-1β (a), TNFα (b) and IFNα (c) were determined by ELISA. Each symbol represents the average of 2 technical replicates of BALF samples from one individual animal. The bars represent the median concentration in pg/ml (IL-1β and TNFα) and ng/ml (IFNα) of 10 animals analyzed from each respective group. Significant differences were calculated by Mann-Whitney-test and calculated p-values were indicated in the graph.