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Characterization of homologous and heterologous adaptive immune responses in porcine reproductive and respiratory syndrome virus infection.

Díaz I, Gimeno M, Darwich L, Navarro N, Kuzemtseva L, López S, Galindo I, Segalés J, Martín M, Pujols J, Mateu E - Vet. Res. (2012)

Bottom Line: In experiment 2, neither the homologous nor the heterologous challenge resulted in detectable viremia although PRRSV was present in tonsils of some animals.Homologous re-inoculation with 3267 produced elevated TGF-β levels in serum for 7-14 days but this did not occur with the heterologous re-inoculation.In conclusion, inoculation with different PRRSV strains result in different virological and immunological outcomes and in different degrees of homologous and heterologous protection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. enric.mateu@uab.cat.

ABSTRACT
The present study characterized the homologous and heterologous immune response in type-I porcine reproductive and respiratory syndrome virus (PRRSV) infection. Two experiments were conducted: in experiment 1, eight pigs were inoculated with PRRSV strain 3262 and 84 days post-inoculation (dpi) they were challenged with either strain 3262 or strain 3267 and followed for the next 14 days (98 dpi). In experiment 2, eight pigs were inoculated with strain 3267 and challenged at 84 dpi as above. Clinical course, viremia, humoral response (neutralizing and non-neutralizing antibodies, NA) and virus-specific IFN-γ responses (ELISPOT) were evaluated all throughout the study. Serum levels of IL-1, IL-6, IL-8, TNF-α and TGF-β were determined (ELISA) after the second challenge. In experiment 1 primo-inoculation with strain 3262 induced viremia of ≤ 28 days, low titres of homologous NA but strong IFN-γ responses. In contrast, strain 3267 induced longer viremias (up to 56 days), higher NA titres (≤ 6 log2) and lower IFN-γ responses. Inoculation with 3267 produced higher serum IL-8 levels. After the re-challenge at 84 dpi, pigs in experiment 1 developed mostly a one week viremia regardless of the strain used. In experiment 2, neither the homologous nor the heterologous challenge resulted in detectable viremia although PRRSV was present in tonsils of some animals. Homologous re-inoculation with 3267 produced elevated TGF-β levels in serum for 7-14 days but this did not occur with the heterologous re-inoculation. In conclusion, inoculation with different PRRSV strains result in different virological and immunological outcomes and in different degrees of homologous and heterologous protection.

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Evolution of the humoral response (ELISA) against PRRSV in experiments 1 and 2. 2a. Average sample to positive (S/P) ratios of optical densities from day +15 to +84 post-inoculation. Empty bars correspond to pigs in experiment 1 (strain 3262: A); grey bars correspond to pigs in experiment 2 (strain 3267: B). Lines show results of control (un-inoculated pigs) in both experiments. 2b. Serological evolution (S/P ratios) of pigs in experiment 1 after the second challenge (84 pi). Empty bars correspond to the homologous challenge (group A + A), grey bars to the heterologous challenge (A + B) and black bars depict results of naïve pigs inoculated for the first time with strain 3267 (C1 + B) 2c. Serological evolution (S/P ratios) of pigs in experiment 2 after the second challenge (84 pi). Empty bars: (B + B); grey bars: B + A; black bars: naïve pigs inoculated for the first time with strain 3262 (C2 + A). In all cases, different superscript letters indicated statistically significant differences (p < 0.05) as determined in the Kruskal-Wallis test; n.s. = non-significant.
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Figure 2: Evolution of the humoral response (ELISA) against PRRSV in experiments 1 and 2. 2a. Average sample to positive (S/P) ratios of optical densities from day +15 to +84 post-inoculation. Empty bars correspond to pigs in experiment 1 (strain 3262: A); grey bars correspond to pigs in experiment 2 (strain 3267: B). Lines show results of control (un-inoculated pigs) in both experiments. 2b. Serological evolution (S/P ratios) of pigs in experiment 1 after the second challenge (84 pi). Empty bars correspond to the homologous challenge (group A + A), grey bars to the heterologous challenge (A + B) and black bars depict results of naïve pigs inoculated for the first time with strain 3267 (C1 + B) 2c. Serological evolution (S/P ratios) of pigs in experiment 2 after the second challenge (84 pi). Empty bars: (B + B); grey bars: B + A; black bars: naïve pigs inoculated for the first time with strain 3262 (C2 + A). In all cases, different superscript letters indicated statistically significant differences (p < 0.05) as determined in the Kruskal-Wallis test; n.s. = non-significant.

Mentions: After inoculation with either one or the other PRRSV strain, pigs rapidly developed antibodies detectable in ELISA although S/P ratios were different among groups. Thus, for the first 84 days pi (except at day 35 pi) S/P ratios were higher (p < 0.05) in animals inoculated with 3267 -experiment 2- than in animals inoculated with 3262- experiment 1- (Figure 2a). After the second challenge (day 84 pi), re-inoculated animals became similar in terms of S/P ratios within each one of the experiments (Figures 2b and 2c).


Characterization of homologous and heterologous adaptive immune responses in porcine reproductive and respiratory syndrome virus infection.

Díaz I, Gimeno M, Darwich L, Navarro N, Kuzemtseva L, López S, Galindo I, Segalés J, Martín M, Pujols J, Mateu E - Vet. Res. (2012)

Evolution of the humoral response (ELISA) against PRRSV in experiments 1 and 2. 2a. Average sample to positive (S/P) ratios of optical densities from day +15 to +84 post-inoculation. Empty bars correspond to pigs in experiment 1 (strain 3262: A); grey bars correspond to pigs in experiment 2 (strain 3267: B). Lines show results of control (un-inoculated pigs) in both experiments. 2b. Serological evolution (S/P ratios) of pigs in experiment 1 after the second challenge (84 pi). Empty bars correspond to the homologous challenge (group A + A), grey bars to the heterologous challenge (A + B) and black bars depict results of naïve pigs inoculated for the first time with strain 3267 (C1 + B) 2c. Serological evolution (S/P ratios) of pigs in experiment 2 after the second challenge (84 pi). Empty bars: (B + B); grey bars: B + A; black bars: naïve pigs inoculated for the first time with strain 3262 (C2 + A). In all cases, different superscript letters indicated statistically significant differences (p < 0.05) as determined in the Kruskal-Wallis test; n.s. = non-significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3403850&req=5

Figure 2: Evolution of the humoral response (ELISA) against PRRSV in experiments 1 and 2. 2a. Average sample to positive (S/P) ratios of optical densities from day +15 to +84 post-inoculation. Empty bars correspond to pigs in experiment 1 (strain 3262: A); grey bars correspond to pigs in experiment 2 (strain 3267: B). Lines show results of control (un-inoculated pigs) in both experiments. 2b. Serological evolution (S/P ratios) of pigs in experiment 1 after the second challenge (84 pi). Empty bars correspond to the homologous challenge (group A + A), grey bars to the heterologous challenge (A + B) and black bars depict results of naïve pigs inoculated for the first time with strain 3267 (C1 + B) 2c. Serological evolution (S/P ratios) of pigs in experiment 2 after the second challenge (84 pi). Empty bars: (B + B); grey bars: B + A; black bars: naïve pigs inoculated for the first time with strain 3262 (C2 + A). In all cases, different superscript letters indicated statistically significant differences (p < 0.05) as determined in the Kruskal-Wallis test; n.s. = non-significant.
Mentions: After inoculation with either one or the other PRRSV strain, pigs rapidly developed antibodies detectable in ELISA although S/P ratios were different among groups. Thus, for the first 84 days pi (except at day 35 pi) S/P ratios were higher (p < 0.05) in animals inoculated with 3267 -experiment 2- than in animals inoculated with 3262- experiment 1- (Figure 2a). After the second challenge (day 84 pi), re-inoculated animals became similar in terms of S/P ratios within each one of the experiments (Figures 2b and 2c).

Bottom Line: In experiment 2, neither the homologous nor the heterologous challenge resulted in detectable viremia although PRRSV was present in tonsils of some animals.Homologous re-inoculation with 3267 produced elevated TGF-β levels in serum for 7-14 days but this did not occur with the heterologous re-inoculation.In conclusion, inoculation with different PRRSV strains result in different virological and immunological outcomes and in different degrees of homologous and heterologous protection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. enric.mateu@uab.cat.

ABSTRACT
The present study characterized the homologous and heterologous immune response in type-I porcine reproductive and respiratory syndrome virus (PRRSV) infection. Two experiments were conducted: in experiment 1, eight pigs were inoculated with PRRSV strain 3262 and 84 days post-inoculation (dpi) they were challenged with either strain 3262 or strain 3267 and followed for the next 14 days (98 dpi). In experiment 2, eight pigs were inoculated with strain 3267 and challenged at 84 dpi as above. Clinical course, viremia, humoral response (neutralizing and non-neutralizing antibodies, NA) and virus-specific IFN-γ responses (ELISPOT) were evaluated all throughout the study. Serum levels of IL-1, IL-6, IL-8, TNF-α and TGF-β were determined (ELISA) after the second challenge. In experiment 1 primo-inoculation with strain 3262 induced viremia of ≤ 28 days, low titres of homologous NA but strong IFN-γ responses. In contrast, strain 3267 induced longer viremias (up to 56 days), higher NA titres (≤ 6 log2) and lower IFN-γ responses. Inoculation with 3267 produced higher serum IL-8 levels. After the re-challenge at 84 dpi, pigs in experiment 1 developed mostly a one week viremia regardless of the strain used. In experiment 2, neither the homologous nor the heterologous challenge resulted in detectable viremia although PRRSV was present in tonsils of some animals. Homologous re-inoculation with 3267 produced elevated TGF-β levels in serum for 7-14 days but this did not occur with the heterologous re-inoculation. In conclusion, inoculation with different PRRSV strains result in different virological and immunological outcomes and in different degrees of homologous and heterologous protection.

Show MeSH
Related in: MedlinePlus