Limits...
Experimental infections of rabbits with proliferative and latent stages of Besnoitia besnoiti.

Liénard E, Pop L, Prevot F, Grisez C, Mallet V, Raymond-Letron I, Bouhsira É, Franc M, Jacquiet P - Parasitol. Res. (2015)

Bottom Line: Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia.Seroconversion occurred in group T without any clinical signs.The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.

View Article: PubMed Central - PubMed

Affiliation: UMR INRA/DGER 1225, INP - École Nationale Vétérinaire de Toulouse, Laboratoire de Parasitologie, 23 chemin des Capelles, F-31076, Toulouse, France, e.lienard@envt.fr.

ABSTRACT
Cattle besnoitiosis due to Besnoitia besnoiti is spreading across Europe and is responsible for severe economic losses in newly infected herds. Experimentally speaking, rabbits have been found to be susceptible to this parasite. The adaptation of B. besnoiti to rabbits may offer a new, easier and cheaper model of investigation for this disease. This study compared the virulence between tachyzoites and bradyzoites of B. besnoiti in rabbits. Eighteen New Zealand rabbits were allocated into three groups of six animals each. The rabbits from the control (group C), "tachyzoite" (group T) and "bradyzoite" (group B) groups were subcutaneously injected in the right flank with 66 μg of ovalbumin, 6.10(6) tachyzoites (125th passage on Vero cells) and 6.10(6) bradyzoites (collected from a natural infected cow) of B. besnoiti, respectively. Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia. Molecular and immunohistochemistry examination was achieved on 25 samples of tissue per rabbit. Seroconversion occurred in group T without any clinical signs. Rabbits of group B exhibited a febrile condition (temperature above 40 °C from day 8 to day 11 following injection) with positive qPCR in blood. Cysts of B. besnoiti were found on skin samples and organs of rabbits from group B in tissue explored with threshold cycle (Ct) values below 30. These results suggest a higher virulence of bradyzoites in rabbits than Vero cell-cultivated tachyzoites. The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.

No MeSH data available.


Related in: MedlinePlus

Evolution of mean rectal temperatures (± standard deviation bars) in each rabbit group. The control, tachyzoite and bradyzoite groups were subcutaneously challenged with 66 μg of ovalbumin, 6.106 tachyzoites and 6.106 bradyzoites of B. besnoiti at day 0, respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4562009&req=5

Fig1: Evolution of mean rectal temperatures (± standard deviation bars) in each rabbit group. The control, tachyzoite and bradyzoite groups were subcutaneously challenged with 66 μg of ovalbumin, 6.106 tachyzoites and 6.106 bradyzoites of B. besnoiti at day 0, respectively

Mentions: No clinical abnormality was observed in rabbits belonging to group C during the whole experimental period and following the injection of ovalbumin. No increase of rectal temperature was found (Fig. 1). A male rabbit (T05) from group T died 3 days after the inoculation of tachyzoites without any clinical sign and fever. The necropsy revealed sudden pancreatitis. For the five remaining rabbits, none of them showed clinical signs, or significant changes in rectal temperature (Fig. 1), at any time-point during the experiment. One male rabbit (B03) died 1 day after the injection of bradyzoites without any clinical signs. No clinical abnormality was found after the necropsy of this rabbit. The five remaining rabbits of group B exhibited fever which started 7 days post-infection (dpi) and lasting 4 days before back to initial values at day 12 (Fig. 1). Rectal temperatures increased to 40.4 °C (ranging from 39.1 to 41.1 °C at 9 and 11 dpi) after returning to normal values (Fig. 1). From days 8 to 10, the rise of rectal temperature was significant in comparison to group C (day 8: p = 0.0303, day 9: p = 0.0173, day 10: p = 0.0043, day 11: p = 0.0043) and group T (day 8: p = 0.0238, day 9: p = 0.0317, day 10: p = 0.00794, day 11: p = 0.00794). In the same period, no significant differences of temperatures were observed between group C and group T. It was accompanied by photophobia for all rabbits in group B from day 8 to day 10. One rabbit exhibited a bilateral nasal discharge at day 7.Fig. 1


Experimental infections of rabbits with proliferative and latent stages of Besnoitia besnoiti.

Liénard E, Pop L, Prevot F, Grisez C, Mallet V, Raymond-Letron I, Bouhsira É, Franc M, Jacquiet P - Parasitol. Res. (2015)

Evolution of mean rectal temperatures (± standard deviation bars) in each rabbit group. The control, tachyzoite and bradyzoite groups were subcutaneously challenged with 66 μg of ovalbumin, 6.106 tachyzoites and 6.106 bradyzoites of B. besnoiti at day 0, respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4562009&req=5

Fig1: Evolution of mean rectal temperatures (± standard deviation bars) in each rabbit group. The control, tachyzoite and bradyzoite groups were subcutaneously challenged with 66 μg of ovalbumin, 6.106 tachyzoites and 6.106 bradyzoites of B. besnoiti at day 0, respectively
Mentions: No clinical abnormality was observed in rabbits belonging to group C during the whole experimental period and following the injection of ovalbumin. No increase of rectal temperature was found (Fig. 1). A male rabbit (T05) from group T died 3 days after the inoculation of tachyzoites without any clinical sign and fever. The necropsy revealed sudden pancreatitis. For the five remaining rabbits, none of them showed clinical signs, or significant changes in rectal temperature (Fig. 1), at any time-point during the experiment. One male rabbit (B03) died 1 day after the injection of bradyzoites without any clinical signs. No clinical abnormality was found after the necropsy of this rabbit. The five remaining rabbits of group B exhibited fever which started 7 days post-infection (dpi) and lasting 4 days before back to initial values at day 12 (Fig. 1). Rectal temperatures increased to 40.4 °C (ranging from 39.1 to 41.1 °C at 9 and 11 dpi) after returning to normal values (Fig. 1). From days 8 to 10, the rise of rectal temperature was significant in comparison to group C (day 8: p = 0.0303, day 9: p = 0.0173, day 10: p = 0.0043, day 11: p = 0.0043) and group T (day 8: p = 0.0238, day 9: p = 0.0317, day 10: p = 0.00794, day 11: p = 0.00794). In the same period, no significant differences of temperatures were observed between group C and group T. It was accompanied by photophobia for all rabbits in group B from day 8 to day 10. One rabbit exhibited a bilateral nasal discharge at day 7.Fig. 1

Bottom Line: Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia.Seroconversion occurred in group T without any clinical signs.The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.

View Article: PubMed Central - PubMed

Affiliation: UMR INRA/DGER 1225, INP - École Nationale Vétérinaire de Toulouse, Laboratoire de Parasitologie, 23 chemin des Capelles, F-31076, Toulouse, France, e.lienard@envt.fr.

ABSTRACT
Cattle besnoitiosis due to Besnoitia besnoiti is spreading across Europe and is responsible for severe economic losses in newly infected herds. Experimentally speaking, rabbits have been found to be susceptible to this parasite. The adaptation of B. besnoiti to rabbits may offer a new, easier and cheaper model of investigation for this disease. This study compared the virulence between tachyzoites and bradyzoites of B. besnoiti in rabbits. Eighteen New Zealand rabbits were allocated into three groups of six animals each. The rabbits from the control (group C), "tachyzoite" (group T) and "bradyzoite" (group B) groups were subcutaneously injected in the right flank with 66 μg of ovalbumin, 6.10(6) tachyzoites (125th passage on Vero cells) and 6.10(6) bradyzoites (collected from a natural infected cow) of B. besnoiti, respectively. Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia. Molecular and immunohistochemistry examination was achieved on 25 samples of tissue per rabbit. Seroconversion occurred in group T without any clinical signs. Rabbits of group B exhibited a febrile condition (temperature above 40 °C from day 8 to day 11 following injection) with positive qPCR in blood. Cysts of B. besnoiti were found on skin samples and organs of rabbits from group B in tissue explored with threshold cycle (Ct) values below 30. These results suggest a higher virulence of bradyzoites in rabbits than Vero cell-cultivated tachyzoites. The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.

No MeSH data available.


Related in: MedlinePlus