Canine parvovirus-2 (CPV-2) is an important pathogen of domestic dogs and wild canids. In Japan, CPV-2 infection remains one of the most common infection diseases among dogs. We analyzed samples collected between 2014 and 2019 to determine the antigenic variants of CPV-2 among dogs in Japan. Our results demonstrated that the CPV-2b variant was predominant. The CPV-2c variant was not found among our samples. Our ndings demonstrate that the distribution of CPV-2 antigenic variants in Japan was more similar to the distribution in Australia compared with that of neighboring countries in Asia.
IntroductionCanine parvovirus-2 (CPV-2) is an important pathogen of domestic dogs and wild canids. CPV-2 is small non-enveloped virus with a single-stranded DNA genome, and classi ed into the family Parvoviridae, subfamily Parvovirinae, genus Protoparvovirus, species Carnivore protoparvovirus-1 [1]. The CPV-2 genome encodes for 4 proteins: NS1, NS2, VP1, and VP2. NS1 and NS2 are non-structural proteins that regulate replication of the viral genome, while VP1 and VP2 are structural proteins that constitute capsids of the virion [2,3]. Amino acid residue in VP2 de nes the antigenic variants of CPV-2 [3]. CPV-2 infection is characterized by gastroenteritis-like symptoms such as fever, anorexia, diarrhea, and vomiting [4]. Unvaccinated adult dogs usually have subclinical infection [5].CPV-2 was identi ed in the late 1970s in dogs [6]. CPV-2 is genetically similar to other carnivore parvoviruses, and presumably derived from feline panleukopenia virus (FPLV) [7]. Within a few years after the outbreak of CPV-2 infection across the United States and Australia in 1978, CPV-2 infection was identi ed in dogs across a number of countries. In the 1980s, two antigenic variants of CPV-2, namely CPV-2a and CPV-2b, emerged [8]. In 2000, a third variant, CVP-2c, was detected in dogs in Italy [9, 10]. These three antigenic variants have a different amino acid in residue 426 of VP2 protein (CPV-2a: N, CPV-2b: D, CPV-2c: E) [8,10,11]. Epidemiological studies over the past 20 years have identi ed these three antigenic variants in the dog population. However, the rst CPV-2 (original CPV-2) has virtually disappeared in the dog population. Studies suggest that there is no difference among the antigenic variants in terms of pathogenicity [12]. However, the licensed CPV2 vaccine is thought to be less effective in protecting dogs against CPV-2c [13].An epidemiological study by Soma et al. [14] demonstrated that CPV-2b was the dominant antigenic variant among dogs in Japan between 2009 and 2011. However, a recent study demonstrated that other antigenic variants are more common in other Asian countries that are geographically close to Japan. For example, the dominant antigenic variant among dogs in Taiwan has shifted from CPV-2b to 16]. Similarly, an epidemiological study in Laos and Vietnam demonstrated that over 90% of infected dogs had the CPV-2c variant [17, 18]. CPV-2c was identi ed in various countries in Asia except in Japan [15][16][17][18][19][20]...
