engleski

Detection of virus infections in fetuses and stillborn piglets from eight Croatian farms

Reproductive failure is important factor influencing economy of pig production. However, majority of cases are caused by non-infectious factors like sow herd management, some infectious agents also occasionally play significant role. These include porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2). In the recent years several new viruses were found to circulate in pig population. These include Torque teno sus virus (TTSuV) and three new parvoviruses (PPV2, 3 and 4) [2]. The role of these viruses in etiology of reproductive failure is not clear. For example TTSuV is commonly present in aborted fetuses and fetuses collected from slaughtered sows [1]. New porcine viruses are being found in healthy and diseased pigs. The aim of this study was to evaluate the presence of PRRSV, PCV2, TTSuV, PPV1, PPV2, PPV3 and PPV4 in cases of reproductive failure in pigs. Materials and Methods For this study 83 fetuses aborted in late gestation and stillborn piglets from 8 large pig farms from Croatia were analyzed. In all of these farms different kind of reproductive disorders, from mild to severe, were observed which included increased pre weaning mortality (7-14%). Affected litters were composed of normal and weak piglets, as well as stillborn and mummified. Fetuses and stillborn piglets were necropsied and samples of heart, lungs, liver and kidneys were collected, fixed in 10% buffered formalin and embedded in paraffin. Tissue sections were stained with H&E. Sections of heart and liver were subjected to ISH for PCV2. The fragments of lungs, spleen, liver were stored in -70°C and subjected to PCR for the presence of PCV2, PRRSV, TTSuV1 and 2 and PPV 1, 2, 3 and 4. Results The most prominent gross lesion was edema which was present in 71 of piglets and fetuses from all farms. Another frequent gross lesion was hydrothorax that was observed in 71 piglets and fetuses from 6 farms. Less frequent lesions were hemorrhages in myocardium (39) and kidneys (37) and heart dystrophy (33). Microscopically, interstitial pneumonia and fat hepatic dystrophy was seen in 35 and 29 fetuses respectively (Fig 1). In tissue of all piglets and fetuses PCV2 and PPV3 were detected by PCR. Other viruses were identified sporadically (Fig 2). Contrary to PCR, ISH for PCV2 did not detect the virus in hearts or livers of any of the piglets or fetuses. Conclusions and Discussion The most common viruses found in piglets and fetuses from the cases of reproductive failure were PCV2 and PPV3. PCV2 was recently proposed to be important factor of reproductive failure in gilts but in the analyzed cases neither characteristic lesions nor PCV2 were found in myocardium. The role of PPV3 in reproductive failure was not explored but our findings warrant further studies in this respect. Other viruses were found sporadically. Interestingly the reproductive failure described as severe was reported only in two farms where PRRSV was detected in aborted fetuses. PV1 was identified in fetuses from the single farm where vaccine against PPV was not used.

reproductive failure; viral infection

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