الفهرس 
The etiological agent of toxoplasmosis
The parasiteOnly 14 pages are availabe for public view
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Abstract
Toxoplasma gondii is an obligate intracellular protozoan that infects humans and a broad range of warm-blooded animals. Toxoplasmosis is one of the most common parasitic zoonotic worldwide diseases.
The present study was divided into two experiments, the first experiment aimed to follow up of T. gondii infection in semen and tissues of experimentally infected rabbit bucks. It carried out on 28 mature male New Zealand rabbits divided into 4 groups.The first group (high dose group) was inoculated subcutaneously (s/c)and intra peritoneal (I/P) with 15×104 tachyzoites of Toxoplasma gondii of RH strain, semen samples were collected pre-inoculation and at weekly post-inoculation (P/I) intervals for two weeks. The second group (immune-competent group) was inoculated s/c with 15×104 tachyzoites of Toxoplasma gondii of RH strain.The third group (immune-suppressive group) was inoculated s/c with 15×104 tachyzoites of Toxoplasma gondii of RH strain and was subjected to immunosuppressive drug regimens. The fourth group was the control.
Semen samples were collected pre-inoculation and at weekly PI intervals for two months. Daily observation of the experimentally infected rabbits revealed that, animals lose their appetite gradually during the first week post-infection and signs of emaciation appeared in few of infected animals. Other clinical findings included nasolacrimal discharges and respiratory disorders were noticed. Our data indicated that there was no significant difference between means of the different treatments concerning MMS, IMP and LSP. Although, an apparent increase in MMS, IMP was recorded in immune suppressed treated group. On the other hand, this group was the lowest in LSP among the other treated groups. Meanwhile, ASP showed significant (P<0.0001) increase in the T. gondii high dose group, immune competent and immune suppressive treated groups compared to the control group. The course of infection in all groups was followed up by examination of collected semen samples for the presence of T. gondii. Application of SYBR real-time PCR revealed positive signals for T. gondii DNA in all samples collected except those of the control group. By using two standard dilutions as positive control, products with melting temperature (Tm) under the melting curve area of standards (81-82°C) considered positive T. gondii.
All samples of control group were negative. All samples collected from experimentally infected rabbits were positive with different load of T. gondii from the 1st week till the 5th weeks post infection. No semen samples could be collected from bucks after the 5th week post infection. The relation between time of sampling of semen post inoculation and T.gondii load in each sample as detected by the qPCR assay was shown that in high dose group(G1) level of infected rabbits was decreased in comparison with that of control group from the first week till the end of experiment after the end of two weeks. The decrease was gradually during this experimental period. In immune-competent group (G2), the parasitic load increased from week 2 till the end of the experiment while in immune-suppressant group (G3), the load was also increased from 2nd week till the end but was higher than the immune-competent group due to an immune-compromising status. The molecular diagnosis by real time PCR detected the parasite in all tissue samples of infected rabbits. Some histopathological changes were detected in different tissues including testes, liver, kidney, lung, spleen and brain.
The second experiment aimed to assess the venereal transmission of T. gondii in female rabbits mated with infected bucks. It carried on four females. It is worth to mention that only one female became pregnant from mating with T. gondii infected rabbit bucks. Two females died while one female didn’t get pregnant. One day post birth, the dam and its fetuses were sacrificed for collection of their tissues. QPCR detected T. gondii DNA in all tissue samples collected from female rabbits sacrificed one day post birth including lung, liver, ovary and uterus. Also, it could detect T. gondii DNA in liver and brain tissues of fetuses sacrificed one day post birth. Histopathological alterations in different tissues were observed. In the present study, Toxoplasma gondii could be detected in body fluids including semen and histopathological alterations could detect in different tissues in infected rabbit. Also, the occurrence of venereal transmission of T. gondii and its effects on different tissues of females and their fetuses can’t be neglected.