Detection of a new cluster of porcine circovirus type 2b strains in domestic pigs in Germany.

PCV2 can be divided into three different genotypes: PCV2a, PCV2b and PCV2c. Since 2004/2005 PCV2b has become the predominant genotype in the domestic pig population worldwide. In the years 2010 and 2012 PCV2b mutant strains (mPCV2), classified as PCV2b-1C strains, were detected in porcine circovirus diseases (PCVD) affected pigs in China and the United States, respectively. Within one year (April 2013-April 2014) newly emerging mPCV2 strains were isolated in seven German pig farms routinely vaccinating against PCV2. Histopathological, clinical and molecular biological findings including in-situ hybridization (ISH) and real-time PCR indicate PCVD in the affected animals. Characterized isolates from five farms were closely related to the PCV2b-1C reference strain BDH (GenBank no. HM038017), whereas strains from two other farms were only 99.1% and 99.0% identical (based on the nucleotide sequence of the complete genome) to mPCV2 strain BDH, respectively.

Histopathological findings in pigs of various ages suffering from spontaneous infection with the porcine reproductive and respiratory syndrome virus (PRRSV).

A retrospective study was carried out to investigate the morphology of 29 routinely necropsied German Landrace pigs of various ages, namely five fetuses, eight neonates, five suckling piglets and 11 weaners, being either serologically PRRSV-positive or born or aborted from PRRSV positive sows. Virus antigen was immunohistochemically demonstrated in 12 out of 27 (44%) lungs tested. The distinguishing histopathological features of PRRSV-induced spontaneous disease are interstitial pneumonia accompanied by secondary inflammatory alterations that become more and more pronounced with increasing age, and vascular alterations hitherto not described in animals of these age groups. The latter consist of vasculitis of the medium-sized arteries and occasionally of the veins, mainly in the lungs but also in other organs, and of perivascular lymphoplasmacytic infiltrates of various degrees of frequency and organ distribution, but present above all in the CNS-including the meninges and in the lungs. These findings, which suggest vasculotropism on the part of the PRRSV, may facilitate the histopathological diagnosis of PRRSV infections in routinely examined material.