Porcine cytomegaly

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The Porcine cytomegalovirus (also called inclusion body , EK or EK rhinitis called) is a viral infectious disease in domestic pigs , are affected by the particularly piglets. The pathogen is the porcine cytomegalovirus . The disease is usually clinically inapparent , less often than a mild, respiratory infection . Severe progression can be observed in piglets and fetuses of pregnant sows that are infected with the virus for the first time during pregnancy .

Pathogen

The porcine cytomegaly is caused by an infection with the porcine cytomegalovirus (PCMV) (taxonomically also called suides herpesvirus 2 ), which belongs to the subfamily Betaherpesvirinae , but not yet assigned to any genus. It is morphologically and also in its pathogenesis very similar to the human cytomegalovirus . PCMV is spread worldwide and is spread through the introduction of latently PCMV-infected animals into the herds. The seroprevalence has only been examined in a few herds; in China it was between 94 and 98% when several herds were examined. The spread of PCMV is favored by intensive animal husbandry . The virus is excreted intermittently by the nasal secretions and urine of latently infected animals , persisting for several weeks after primary infection. It persists in macrophages in the lungs for life . PCMV cannot infect humans, although it could cause problems in a possible future xenotransplantation of porcine organs to humans (under the condition of post-transplant immunosuppression ), as can be concluded from transplantation experiments with primates. In vitro , human fibroblasts and epithelial cells can be productively infected in cell culture.

Clinical picture

The infection with the PCMV proceeds predominantly without clinical symptoms or with only mild, short respiratory symptoms. By smear infection with nasal secretions infected animals, the PCMV reaches the glandular cells of the nasal mucosa as the primary place of multiplication. B. in macrophages to epithelial cells of other organs ( salivary glands , lungs , kidney tissue ). Antibodies are formed after 10 to 14 days and cellular immunity is very likely to keep the virus in latency .

The infection is much more severe during pregnancy. The primary infection of (PCMV-negative) pregnant sows can lead to an infection of the fetus. In this case - since maternal antibodies are not formed quickly enough and reach the fetus via the placenta - the fetal infection leads to fruit death with subsequent mummification or fruit resorption . If the infection occurs close to the due date, weak or barely viable piglets can be the result.

If piglets from PCMV-negative sows are infected in the first weeks of life, they often show non-purulent rhinitis with inflammatory and degenerative defects of the nasal mucosa, nasal discharge and sneezing after an incubation period of around ten days . Breathing difficulties and growth retardation due to poor milk intake may also occur, and less often conjunctivitis or epistaxis . The inclusion bodies typical of the disease are particularly visible in glandular tissue, and in fetal infections also in the lungs, liver and kidneys. After one to two weeks, the acute porcine cytomegaly is usually over if the housing conditions are favorable and the mortality rate is low. Piglets from sows that have been infected for a long time are protected from the disease by passive antibody acquisition via the placenta or by ingestion of the colostrum after birth ( nest protection ).

Diagnosis

Basophil inclusion bodies (EK) in lung tissue in cytomegaly. A free halo forms around the EKs, so that the cells have the typical appearance of so-called " owl eye cells "

The diagnosis is usually made serologically in the virological laboratory by detecting specific anti-PCMV antibodies in indirect immunofluorescence or a Western blot . Virus isolation in cell culture on fibroblast cultures or pig macrophages is possible as direct evidence . In the fibroblast culture, inclusion bodies form as a typical sign, a cytopathic effect can be visible. A qualitative and quantitative detection of PCMV by means of PCR is possible from serum , nasal swabs or tissue samples. Postmortem , large, basophilic inclusion bodies are histologically visible in the respiratory mucosa, the salivary glands and in the kidney tissue. The inclusion bodies can also be observed intra-vitam in nasal mucosal tissue obtained by swabs ( brush swabs ).

The clinical picture is the differential diagnosis a atrophic rhinitis delineate.

Therapy and prevention

Specific antiviral therapy has not been tested in sick animals. In investigations of xenotransplants with organ transplants from pigs to baboons , which can lead to severe systemic disease with disseminated intravascular coagulation in baboons after reactivation of the PCMV from the porcine organs , ganciclovir and cidofovir have proven to be sufficiently effective antivirals . A vaccine against the porcine cytomegalovirus is not available. The only preventive measures currently available are sufficiently good hygiene and improved husbandry conditions for the pig herds.

literature

  • H.-J. Sebitz, U. Truyen, P. Valentin-Weigand (editor): Veterinary microbiology, infection and disease theory. Enke-Verlag Stuttgart, 10th edition 2015, ISBN 9783830412625 , pp. 439-440

Individual evidence

  1. ↑ GH Liu et al .: Seroprevalence of porcine cytomegalovirus and sapovirus infection in pigs in Hunan province, China. Arch. Virol. (2012) 157 (3): pp. 521-524 PMID 22167251
  2. ↑ JL Whitteker et al .: Human fibroblasts are permissive for porcine cytomegalovirus in vitro. Transplantation (2008) 86 (1): pp. 155-162 PMID 18622293
  3. ↑ M. Degré et al .: Human cytomegalovirus productively infects porcine endothelial cells in vitro. Transplantation (2001) 72 (7): pp. 1334-1337 PMID 11602867
  4. ↑ E. Plotzki et al .: A new Western blot assay for the detection of porcine cytomegalovirus (PCMV) . J. Immunol. Methods (2016) S0022-1759 (16): pp. 30154-30155 PMID 27498035
  5. ^ VA Morozov, AV Morozov, J. Denner: New PCR diagnostic systems for the detection and quantification of porcine cytomegalovirus (PCMV). Arch. Virol. (2016) 161 (5): pp. 1159-1168 PMID 26839086
  6. ↑ JF Fryer et al .: Susceptibility of porcine cytomegalovirus to antiviral drugs. J. Antimicrob. Chemother. (2004) 53 (6): pp. 975-980 PMID 15117919