Vírus da artrite e encefalite caprina (CAEV) no trato reprodutivo de cabras naturalmente infectadas e risco de transmissão pela transferência de embriões

Abstract

The study was conducted in steps, first a serological survey in five major producing properties of goat milk in the state of Minas Gerais, to identify the occurrence of anti-CAEV antibodies. A second study was to investigate the presence of CAEV in the reproductive tract of naturally infected goats and a third the risk was conducted to evaluate the virus transmission by embryo transfer. Five properties located in different cities in the state of Minas Gerais were evaluated, totaling 1072 animals of different ages and races (Toggenburg, Alpine and Saanen). The study on the presence of the virus in the uterus these being selected as embryo donors. Embryos recovered through transcervical flushing were subjected to inner cell mass puncture using a micromanipulador. The two parties of the embryos were individualized. Where they recovered the reproductive tract (vagina cervix, uterus and ovaries), the recovered material was diagnostic by PCR Nested. Finally, the third study, in a commercial flock positive goat to CAEV was selected as donors and negative goats to CAEV as embryo recipients. 23 embryos were recovery by transcervical flushing from five donors washed with trypsin and subsequently transferred to recipients also through transcervical way.Throughout the gestational period (five months) and four postnatal months total blood was collected once a month of the recipients for CAEV diagnosing by Nested PCR method. The monitoring was also performed by the same method of diagnosis in animals born during the first four months of life. The occurrence of anti-CAEV antibodies in the studied properties was 49.5% (531/1072). According the results, a high occurrence of seropositive animals was identified in the state of Minas Gerais, which has one of the largest herds of dairy goats in Brazil. Therefore to emphasizes the need to adopt new technologies on the properties as the separation of infected and healthy animals. The exclusion of positive breeding in properties is also a measure of control, it has been demonstrated that these are an important route of transmission. Tissues studied also showed positive results for the presence of pro-virus and viruses, indicating that may be occurring viral replication in the reproductive tract. However the embryos from this medium, in two parts: the zone pellucida and inner cell mass have not shown the expression of DNA or RNA, which confirms the zone pellucida protection capacity of 18 the same. Throughout the period investigated, no proviral DNA was identify in the recipients blood. Newborns during the four-month evaluation were also seronegative. The present study did not show the transmission of CAEV by embryos from positive goats after trypsin washes. According to the results, a high occurrence of seropositive animals was identified in the state of Minas Gerais, which has one of the largest herds of dairy goats in Brazil. The transcervical washing proved to be potentially method to reduce the virus concentration in reproductive tract, since the amount of fluid infused in the uterus could reduce the concentration of free virus in reproductive tract. Therefore, it can be inferred that embryos derived from naturally infected goats, even in the presence of pro-virus and virus free in uterine lumen are apparently not permissive to CAEV infection due to the presence of intact zone pellucida and transcervical flushing can reduce the risk of virus transmission.