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Bovine leukemia virus p24 antibodies reflect blood proviral load.

Gutiérrez G, Carignano H, Alvarez I, Martínez C, Porta N, Politzki R, Gammella M, Lomonaco M, Fondevila N, Poli M, Trono K - BMC Vet. Res. (2012)

Bottom Line: The mean of high PVL reactors within weak p24 reactors was 17.38% (SD = 8.92).In 5/15 farms, the number of weak p24 reactors with high PVL was lower than 10%.We found that the humoral response reflected the level of in vivo infection, and may therefore have useful epidemiological applications.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias y Agronómicas, INTA, C.C. 1712, Castelar, Argentina. ggutierrez@cnia.inta.gov.ar

ABSTRACT

Background: Bovine leukemia virus (BLV) is worldwide distributed and highly endemic in Argentina. Among the strategies to prevent BLV dissemination, a control plan based on the selective segregation of animals according to their proviral load (PVL) is promising for our dairy productive system. The objective of this work was to study the relationship between the blood PVL and the antibody level, in order to identify whether the individual humoral response, i.e. the anti-p24 or anti-whole-BLV particle, could be used as a marker of the blood level of infection and thus help to recruit animals that may pose a lower risk of dissemination under natural conditions.

Results: The prevalence of p24 antibodies on the 15 farms studied was over 66%. The prevalence of p24 and whole-BLV antibodies and PVL quantification were analyzed in all the samples (n = 196) taken from herds T1 and 51. ROC analysis showed a higher AUC for p24 antibodies than whole-BLV antibodies (Z(reactivity): 3.55, P < 0.001; Z(titer): 2.88, P < 0.01), and as consequence a better performance to predict the proviral load status in herd 51. No significant differences were found between the performance of p24 and whole-BLV antibodies in herd T1. A significant positive correlation was observed between PVL values and p24 antibody reactivity in both farms (r (T1) = 0.7, P < 0.001, r (51) = 0.71, P < 0.0001). The analysis was extended to the whole number of weak p24 antibody reactors (n = 311) of the other 13 farms. The mean of high PVL reactors within weak p24 reactors was 17.38% (SD = 8.92). In 5/15 farms, the number of weak p24 reactors with high PVL was lower than 10%.

Conclusions: We found that the humoral response reflected the level of in vivo infection, and may therefore have useful epidemiological applications. Whereas the quantitative evaluation of blood proviral load using real-time PCR is expensive and technically demanding, the measurement of antibodies in blood by ELISA is relatively straightforward and could therefore constitute a cost-effective tool in a BLV control intervention strategy, especially in highly infected herds such as Argentinean dairy ones.

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Proviral load distribution in weak p24 antibody reactivity animals from 15 dairy herds. p24 seropositive animals were selected from 15 herds and analyzed for BLV proviral load. The percentages of animals with undetectable/low (U/L) and high (H) proviral load are shown. Ab) antibody.
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Figure 4: Proviral load distribution in weak p24 antibody reactivity animals from 15 dairy herds. p24 seropositive animals were selected from 15 herds and analyzed for BLV proviral load. The percentages of animals with undetectable/low (U/L) and high (H) proviral load are shown. Ab) antibody.

Mentions: A significant positive correlation was observed between PVL values and p24 antibody reactivity in both farms (r T1 = 0.7, P < 0.001, r 51 = 0.71, P < 0.0001), where the rate of animals with high PVL increased in concordance with the antibody category, and varied from 8.3 to 13% in weak reactors and from 47.6 to 61% in strong ones (Figure 3). According to the above findings that showed that a weak p24 antibody reactivity could be a good indicator of low PVL, the analysis was extended to the whole number of weak p24 antibody reactors (n = 311) of the other 13 farms, where 12.5% to 31.1% of all the seroreactors showed weak reactivity (Mean = 21.23, SD = 5.44) (Table 1). Figure 4 shows the distribution of PVL in the weak p24 antibody reactors from the different farms. The mean of high PVL reactors within this group was 17.38% (SD = 8.92). In 5/15 farms, the number of high PVL animals was lower than 10%. The highest proportion of high PVL animals was 33.3% on Farm 61, which showed 22.9% of the animals within the weak p24 subgroup (Table 1).


Bovine leukemia virus p24 antibodies reflect blood proviral load.

Gutiérrez G, Carignano H, Alvarez I, Martínez C, Porta N, Politzki R, Gammella M, Lomonaco M, Fondevila N, Poli M, Trono K - BMC Vet. Res. (2012)

Proviral load distribution in weak p24 antibody reactivity animals from 15 dairy herds. p24 seropositive animals were selected from 15 herds and analyzed for BLV proviral load. The percentages of animals with undetectable/low (U/L) and high (H) proviral load are shown. Ab) antibody.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3526540&req=5

Figure 4: Proviral load distribution in weak p24 antibody reactivity animals from 15 dairy herds. p24 seropositive animals were selected from 15 herds and analyzed for BLV proviral load. The percentages of animals with undetectable/low (U/L) and high (H) proviral load are shown. Ab) antibody.
Mentions: A significant positive correlation was observed between PVL values and p24 antibody reactivity in both farms (r T1 = 0.7, P < 0.001, r 51 = 0.71, P < 0.0001), where the rate of animals with high PVL increased in concordance with the antibody category, and varied from 8.3 to 13% in weak reactors and from 47.6 to 61% in strong ones (Figure 3). According to the above findings that showed that a weak p24 antibody reactivity could be a good indicator of low PVL, the analysis was extended to the whole number of weak p24 antibody reactors (n = 311) of the other 13 farms, where 12.5% to 31.1% of all the seroreactors showed weak reactivity (Mean = 21.23, SD = 5.44) (Table 1). Figure 4 shows the distribution of PVL in the weak p24 antibody reactors from the different farms. The mean of high PVL reactors within this group was 17.38% (SD = 8.92). In 5/15 farms, the number of high PVL animals was lower than 10%. The highest proportion of high PVL animals was 33.3% on Farm 61, which showed 22.9% of the animals within the weak p24 subgroup (Table 1).

Bottom Line: The mean of high PVL reactors within weak p24 reactors was 17.38% (SD = 8.92).In 5/15 farms, the number of weak p24 reactors with high PVL was lower than 10%.We found that the humoral response reflected the level of in vivo infection, and may therefore have useful epidemiological applications.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias y Agronómicas, INTA, C.C. 1712, Castelar, Argentina. ggutierrez@cnia.inta.gov.ar

ABSTRACT

Background: Bovine leukemia virus (BLV) is worldwide distributed and highly endemic in Argentina. Among the strategies to prevent BLV dissemination, a control plan based on the selective segregation of animals according to their proviral load (PVL) is promising for our dairy productive system. The objective of this work was to study the relationship between the blood PVL and the antibody level, in order to identify whether the individual humoral response, i.e. the anti-p24 or anti-whole-BLV particle, could be used as a marker of the blood level of infection and thus help to recruit animals that may pose a lower risk of dissemination under natural conditions.

Results: The prevalence of p24 antibodies on the 15 farms studied was over 66%. The prevalence of p24 and whole-BLV antibodies and PVL quantification were analyzed in all the samples (n = 196) taken from herds T1 and 51. ROC analysis showed a higher AUC for p24 antibodies than whole-BLV antibodies (Z(reactivity): 3.55, P < 0.001; Z(titer): 2.88, P < 0.01), and as consequence a better performance to predict the proviral load status in herd 51. No significant differences were found between the performance of p24 and whole-BLV antibodies in herd T1. A significant positive correlation was observed between PVL values and p24 antibody reactivity in both farms (r (T1) = 0.7, P < 0.001, r (51) = 0.71, P < 0.0001). The analysis was extended to the whole number of weak p24 antibody reactors (n = 311) of the other 13 farms. The mean of high PVL reactors within weak p24 reactors was 17.38% (SD = 8.92). In 5/15 farms, the number of weak p24 reactors with high PVL was lower than 10%.

Conclusions: We found that the humoral response reflected the level of in vivo infection, and may therefore have useful epidemiological applications. Whereas the quantitative evaluation of blood proviral load using real-time PCR is expensive and technically demanding, the measurement of antibodies in blood by ELISA is relatively straightforward and could therefore constitute a cost-effective tool in a BLV control intervention strategy, especially in highly infected herds such as Argentinean dairy ones.

Show MeSH
Related in: MedlinePlus