Increased cytokine and nitric oxide levels in serum of dogs experimentally infected with Rangelia vitalii.

This study aimed to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NO x ) in serum of dogs experimentally infected with Rangelia vitalii. Twelve female mongrel dogs were divided into 2 groups; group A (uninfected controls) composed by healthy dogs (n=5) and group B consisting of dogs inoculated with R. vitalii (n=7). Animals were monitored by blood smear examinations, which showed intraerythrocytic forms of the parasite on day 5 post-infection (PI). Blood samples were collected through the jugular vein on days 0, 10, and 20 PI to determine the serum levels of IFN-γ, TNF-α, IL-1, IL-6, and NO x . Cytokines were assessed by ELISA quantitative sandwich technique, and NO x was measured by the modified Griess method. Cytokine levels (IFN-γ, TNF-α, IL-1, and IL-6) were increased (P<0.01) in serum of infected animals. Serum levels of NO x were also increased on days 10 PI (P<0.01) and 20 PI (P<0.05) in infected animals. Therefore, the infection with R. vitalii causes an increase in proinflammatory cytokines and nitric oxide content. These alterations may be associated with host immune protection against the parasite.

Serum proteinogram, acute phase proteins and immunoglobulins in dogs experimentally infected with Rangelia vitalii.

The present study aimed to evaluate the serum proteinogram, acute phase proteins (APPs) and immunoglobulins (Igs) of dogs experimentally infected by Rangelia vitalii in the acute phases of the disease. Banked serum samples collected on days 0, 10 and 20 during a previously reported R. vitalii experimental infection were used to analyze the serum proteinogram, APPs (C-reactive protein - CRP and alpha-1-acid glycoprotein - AGP) and Igs (IgM, IgG, IgA and IgE) in the current study. Total protein and albumin level were significantly (P<0.05) decreased at day 10 PI and 20 PI in infected sera compared to the control sera. Alpha-1 globulin (day 10 PI) and gamma globulin (day 20 PI) were increased (P<0.01) in infected sera. Alpha-2 globulin (days 10 and 20 PI) and beta-2 globulin (day 10 PI) were decreased (P<0.05) in infected sera compared to control sera. Beta-1 globulin fraction did not differ statistically between sera. Serum CRP and AGP concentrations were significantly increased (P<0.05) at days 10 and 20 PI in infected sera. IgG was increased at days 10 (P<0.05) and 20 PI (P<0.01) in infected sera. Furthermore, it was also observed an increase (P<0.01) in the levels of IgM, IgA, and IgE in infected sera than control sera. We conclude that R. vitalii infection causes alterations in the proteinogram, and increases in the levels of APPs and Igs. Further studies are essentials to define the causes of these pathological changes in this disease.

Activities of ectonucleotidases and adenosine deaminase in platelets of dogs experimentally infected with Rangelia vitalii.

Rangeliosis is a disease which affects dogs in Brazil, caused by a piroplasm known as Rangelia vitalii. This disease causes a lot of clinico-pathological features, including the coagulation disorders associated with bleeding. The cause of these changes has not yet been determined. Considering the association of purinergic system and hemostasis this study aimed to evaluate the activity of enzymes that hydrolyze ATP, ADP and AMP; and deamination of adenosine in platelets from dogs experimentally infected with R. vitalii. For this study, 12 healthy young dogs (females) were used, separated in two groups. Group A (n=5) were uninfected controls, and group B were experimentally infected with R. vitalii (n=7). After being inoculated with R. vitalii-infected blood, animals were monitored by blood smear examinations, which showed intra-erythrocytic forms of the parasite after five days post-inoculation (PI). Blood samples were collected to quantitate and separate platelets (Day 0, 12 and 21 PI) and to measure the enzymatic activities (Day 12 and 21 PI). The activity of NTPDase, 5'-nucleotidase and adenosine deaminase (ADA) was measured in platelets. A reduction (P<0.01) in the number of platelets was observed in R. vitalii-infected blood at Days 12 and 21 PI. At Day 12 PI, a reduction (P<0.01) in the hydrolysis of ATP, ADP and AMP, and deamination of adenosine was observed in dogs infected with R. vitalii. At Day 21 PI the ADA activity remained decreased, unlike the activity of NTPDase which increased (P<0.05). Based on these results we can conclude that ATP, ADP and AMP hydrolysis and adenosine deamination were altered in platelets of R. vitalii-infected dogs. Considering the importance of the purinergic system in hemostasis, it is believed that those changes contribute to the coagulation disorders and bleeding observed in R. vitalii-infected dogs and discussed in this manuscript.