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 p orcine circovirus type 2 (PCV2) in the semen of infected boars. Four mature boars were inoculated intranasally with PCV2 isolate LHVA-V53 propagated o n PK15 cells. Two boars inoculated with the supernatant of noninfected PK15 cells were kept as controls. Serum samples were collected from all boars a t 4, 7, 11, 13, 18, 21, 25, 28, 35, and 55 days postinoculation (dpi) and f rom the four PCV2-infected boars at 90 dpi. Samples were tested for the pre sence of antibodies to PCV2 by an indirect immunofluorescence assay and for the presence of PCV2 DNA by PCR and nested PCR Semen samples were collecte d from all six boars at 5, 8, 11, 13, 18, 21, 25, 28, 33, and 47 dpi and te sted for the presence of PCV2 DNA by a nested PCR assay. Antibodies to PCV2 could be detected as early as II dpi in one boar, and all four infected bo ars were found positive for PCV2 antibodies by 18 dpi. Thereafter all infec ted boars remained positive for antibodies to PCV2 until 90 dpi. Analysis o f serum samples by nested PCR demonstrated the presence of PCV2 DNA as earl y 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 negativ e at 90 dpi. PCV2 DNA was detected as soon as 5 dpi in the semen of two inf ected 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 sug gests that PCV2 may be shed intermittently in the semen of infected boars.