Whole-Genome Sequence of a Porcine Circovirus Type 2 Strain Detected in Assam, India

Porcine circovirus-associated disease caused by porcine circovirus type 2 (PCV2) is a vital threat to the global pig industry. In this study, we have characterized the complete genome sequence of a PCV2 isolate, namely, Assam-01, belonging to the genotype PCV2d.

Vorkommen von Genotypen des porzinen Circovirus Typ 2 (PCV2) in Schweinebeständen mit unterschied lichen Impfstrategien gegen PCV2

Zusammenfassung Ziel: Seit den Jahren 2004/2005 zeigt sich beim porzinen Circovirus (PCV2) weltweit eine Veränderung der Nachweisrate vom Genotyp PCV2a zu PCV2b. Da alle kommerziell verfügbaren Impfstoffe auf dem Genotyp PCV2a basieren, hatte die Studie das Ziel, das Vorkommen von PCV2a und PCV2b in Beständen mit unterschiedlichen Impfstrategien gegen PCV2 zu evaluieren. Methoden: In die Studie gingen 405 Ferkel aus neun Beständen (jeweils drei Bestände mit Mutterschutzimpfung [SI], Ferkelimpfung fi bzw. ohne Impfung gegen PCV2 [NI]) ein. Der PCV2-Status der Tiere wurde vom 3. Lebenstag bis zur Schlachtung verfolgt. Das Serum wurde mittels PCR quantitativ auf PCV2-DNA untersucht, positive Proben anschließend in einer genotypdifferenzierenden Duplex-PCR analysiert und die PCV2-Isolate nach Sequenzierung des Gesamtgenoms phylogenetisch zugeordnet. Die Daten von 383 Tieren konnten ausgewertet werden. Ergebnisse: Der Nachweis von PCV2 gelang in acht Beständen (1x PCV2a; 6x PCV2b; 1x PCV2a und PCV2b). PCV2b ließ sich in FI-, SI-, und NI-Beständen, PCV2a nur in SI- und NI-Beständen nachweisen. 55,4% aller Ferkel erwiesen sich mindestens einmal im Untersuchungszeitraum PCV2-positiv (FI: 7,8%, SI: 65,4%, NI: 93,7%). Davon waren 4,7% PCV2a-, 92,2% PCV2b- und 2,4% für PCV2a sowie PCV2b positiv. Der mittlere PCV2-DNA-Gehalt lag bei PCV2b-positiven Tieren signifikant höher als bei PCV2a-positiven Tieren. Die Isolate konnten als PCV2b-1A (5/9 Beständen), PCV2b-1B (1/9 Beständen) und PCV2a-2D (2/9 Beständen) identifiziert werden. Schlussfolgerung und klinische Relevanz: Die seit 2004/2005 beobachtete höhere Nachweisrate von PCV2b im Vergleich zu PCV2a wurde bestätigt. Die Ergebnisse weisen darauf hin, dass der Einsatz auf PCV2a basierender Vakzinen bei Ferkeln zu einer weiteren Verschiebung der Nachweisrate zugunsten von PCV2b führt. Um die klinische Relevanz dieser Beobachtung abschätzen zu können, sollten umfangreichere vergleichende Untersuchungen erfolgen, die die Effektivität von PCV2a-Impfstoffen in PCV2a- und PCV2b-positiven Beständen berücksichtigen.

Experimental Airborne Transmission of Porcine Postweaning Multisystemic Wasting Syndrome

The objective of these studies was to investigate if porcine postweaning multisystemic wasting syndrome (PMWS) could be induced in healthy pigs following contact with air from pigs with clinical signs of PMWS. The pigs were housed in different units. Either 31 (study I) or 25 (study II) pigs with clinical symptoms of PMWS from a PMWS-affected herd and 25 healthy pigs from a PMWS-free, but PCV2-positive, herd were housed in unit A. Fifty pigs from a PMWS-free herd were housed in unit B, which were connected by pipes to unit A. In unit C, 30 pigs from a PMWS-free herd were housed as controls. In study II, the pigs in units A and B from the PMWS-free herd developed clinical signs of PMWS 2-3 weeks after arrival. PMWS was confirmed at necropsy and the diseased pigs had increased PCV2 load and increased antibody titers against PCV2 in serum that coincided with the development of clinical signs typical of PMWS. Sequence analysis revealed that the PCV2 isolate belonged to genotype 2b. In conclusion, the present study showed that PMWS can be induced in pigs from a PMWS-free herd by airborne contact with pigs from a PMWS-affected herd.

First description of postweaning multisystemic wasting syndrome (PMWS) in wild boar ( Sus scrofa ) in Croatia and phylogenetic analysis of partial PCV2 sequences

This report describes the first case of postweaning multisystemic wasting syndrome (PMWS) in wild boar in Croatia. During the winter season of 2004, eight wild young piglets (of approximately 2 to 5 months of age) were found dead in a fenced hunting area. Polymerase chain reaction (PCR) was carried out on measenteric lymph nodes and all animals yielded positive results. In one of these animals diagnosis of PMWS was established based on the three key diagnostic criteria including the clinical manifestation, moderate lymphoid lesions consisting of lymphocyte depletion and granulomatous inflammation, and detection of the presence of PCV2 genome within the lymphoid lesions by in situ hybridisation (ISH). Three additional wild piglets had also mild PMWS-like lesions and a low amount of PCV2 was also found. No PMWS-like lesions or PCV2 genome were detected in the rest of the wild piglets studied. Three PCR-positive isolates were partially sequenced, which confirmed the diagnosis of PCV2 and demonstrated that the three sequences were genetically identical. The phylogenetic analysis of a representative PCV2 isolate indicated that its sequence (DQ875444) is grouped in a separate branch with Hungarian isolate (AY256460) and differs from any of the annotated sequences.

Porcine Circovirus 2–Associated Disease in Eurasian Wild Boar

Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2-like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.

PCR Detection and Evidence of Shedding of Porcine Circovirus Type 2 in Boar Semen

An experimental study was conducted to evaluate the potential presence of porcine circovirus type 2 (PCV2) in the semen of infected boars. Four mature boars were inoculated intranasally with PCV2 isolate LHVA-V53 propagated on PK15 cells. Two boars inoculated with the supernatant of noninfected PK15 cells were kept as controls. Serum samples were collected from all boars at 4, 7, 11, 13, 18, 21, 25, 28, 35, and 55 days postinoculation (dpi) and from the four PCV2-infected boars at 90 dpi. Samples were tested for the presence of antibodies to PCV2 by an indirect immunofluorescence assay and for the presence of PCV2 DNA by PCR and nested PCR. Semen samples were collected from all six boars at 5, 8, 11, 13, 18, 21, 25, 28, 33, and 47 dpi and tested for the presence of PCV2 DNA by a nested PCR assay. Antibodies to PCV2 could be detected as early as 11 dpi in one boar, and all four infected boars were found positive for PCV2 antibodies by 18 dpi. Thereafter all infected boars remained positive for antibodies to PCV2 until 90 dpi. Analysis of serum samples by nested PCR demonstrated the presence of PCV2 DNA as early as 4 dpi in three of four infected boars. Serum samples from all infected boars were positive for PCV2 DNA from 11 dpi until 35 dpi but were negative at 90 dpi. PCV2 DNA was detected as soon as 5 dpi in the semen of two infected boars and intermittently thereafter in the semen of all four infected boars. The semen of two infected boars was positive for PCV2 DNA at 47 dpi. Following infection, PCV2 DNA can be detected in semen concurrently with the presence of PCV2 DNA and antibodies in the serum. The present study suggests that PCV2 may be shed intermittently in the semen of infected boars.