PhD Thesis Demeter Zoltan

(Decaro et al., 2007b). There is an ongoing dispute regarding the effectiveness of type 2
based vaccines against the new variants of the virus, but it is generally accepted that
they induce a sufficient protective response (Truyen, 2006; Spibey et al., 2008).
3.3.6 Genetic characteristics of the pathogen
The genetic organization of CPV2 is very similar to the FPV genome. CPV2 contains a
linear single stranded DNA of about 5200 kb. The genome has two ORFs: a left hand
ORF encodes two non structural proteins (NS1 and NS2), and a right handed ORF
encodes the two capsid proteins (VP1 and VP2), which are translated from alternatively
spliced mRNA (Fig. 4; Reed et al., 1988; Horiuchi et al., 1998).
Fig. 4: Genetic organization of CPV2, with special emphasis on the aa present in
postion 426 of VP2, the basis of CPV2 genotyping
Previous studies have demonstrated that the host range of parvoviruses is
determined by the VP2 gene (Parrish, 1991; Chang et al., 1992). Characterization of
CPV2/FPV chimeric viruses revealed that the host range of CPV2 is determined by
aa93, 103 and 323 in VP2 (Chang et al., 1992; Horiuchi et al., 1998). Due to this fact
the VP2 gene is most suitable for the genetic analysis of parvoviruses.
3.3.7 Genetic diversity
An extensive study by Decaro et al. (2007a) on the molecular epidemiology of CPV2
reveals that all genotypes of the virus are currently circulating in Europe, but there
seems to be an evident diversity in the geographical distribution: while the new variant
2c is widespread in countries such as Italy, Portugal and Germany, and is sporadic in the
UK, CPV2a is most frequent in Belgium, whereas in the UK, Germany and Italy it has
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