Genotyping of porcine circovirus type 2 from a variety of clinical conditions in China

doi:10.1016/j.vetmic.2005.07.003

Veterinary Microbiology

Volume 110, Issues 1–2, 30 September 2005, Pages 141-146

https://doi.org/10.1016/j.vetmic.2005.07.003 Get rights and content

Abstract

Genotypes of porcine circovirus type 2 (PCV2) in clinical tissue specimens collected from pigs of different region in China between 2001 and 2003 were analyzed by PCR and restriction fragment length polymorphism (RFLP) analysis of PCV2 genomic DNA encompassing the complete ORF2. The results showed that nine different genotypes (A–I) were identified and designated CHN-2A, CHN-2B, CHN-2C, CHN-2D, CHN-2E, CHN-2F, CHN-2G, CHN-2H and CHN-2I, respectively. Amongst the genotypes, 0.6% were CHN-2A (1/173), CHN-2B (1/173) and CHN-2C (1/173) RFLP profile; 2.3% were CHN-2F (4/173) and CHN-2G (4/173); 5.8% were CHN-2D (10/173); 8.6% were CHN-2E (15/173); 18.5% were CHN-2I (32/173) and 60.7% were CHN-2H (105/173). Therefore, our results suggest that CHN-2H is the dominant genotype of PCV2 prevailing in China. Sequence analysis revealed that ORF2 genes of different genotypic PCV2 exhibited the variation extent of 90.5–99.5% and 88–100% in nucleotide and amino acid respectively. The deduced amino acid sequences alignment of the capsid protein encoded by ORF2 of PCV2 presented that three major regions with greater heterogeneity existed at residues 57–90, 121–136 and 180–191 among nine genotypic PCV2. It was concluded that there exist variation in ORF2 genes of different genotypic PCV2 prevailing in China.

Introduction

Porcine circovirus (PCV), a member of the family Circoviridae (Lukert et al., 1995), is a small, non-enveloped DNA virus containing an unique covalently closed circular single-stranded genomic DNA of about 1.76 Kb (Tischer et al., 1982). Two genotypes of PCV, PCV1 originally identified in the porcine kidney (PK15) cell line (ATCC-CCL31) (Tischer et al., 1982) and PCV2 associated with postweaning multisystemic wasting syndrome (PMWS) (Harding and Clark, 1997, Allan et al., 1998, Ellis et al., 1998), have been recognized (Hamel et al., 1998, Meehan et al., 1998, Morozov et al., 1998, Mankertz et al., 2000). Previous studies indicated that the genetic variations of PCV2 might be associated with geographic origin rather than with differences in tropism (Fenaux et al., 2000, Meehan et al., 2001), and PCV2 could be categorized into different genotypes according to ORF2 restriction fragment length polymorphism (RFLP) analysis of PCV2 (Hamel et al., 2000).

PMWS, a newly emerging swine disease originally reported in Canada (Harding and Clark, 1997, Allan et al., 1998, Ellis et al., 1998) have been acknowledged in many European countries, in the US and in some Asian countries. Moreover, PCV2 was found to be associated with other clinical conditions of pigs including porcine dermatitis and nephropathy syndrome (PDNS) (Rosell et al., 2000), late-term abortions (West et al., 1999) and reproductive failure in sows (Park et al., 2005). Therefore, the diseases associated with PCV2 infection have been becoming a major and complicated problem to swine industry worldwide. In China, clinical PMWS associated with PCV2 infection in 6–8 week-old pigs was first reported in 2002 (Wang et al., 2002). Subsequently, PCV2 was detected and identified in the tissue samples collected from the diseased pig (Lu et al., 2002). In this paper, we report the genotypes of PCV2 in clinical tissue specimens determined based on RFLP analysis of ORF2 of PCV2 in order to better understand the molecular epidemiology of PCV2 in China.

Section snippets

Materials and methods

Tissue samples (lung, spleen, lymph nodes, kidney) were collected from pig farms of different regions of China during 2001–2003. Totally, 333 tissue samples were obtained from 118 dead and 215 diseased pigs presenting clinical signs and lesions associated with PMWS, PDNS, respiratory condition and diarrhea. The samples were stored at −80 °C for use.

For tissue samples, homogenates comprising 1:5 tissue/phosphate buffer saline (PBS) were obtained after grinding in a glass homogenizer, and were

Results

The presence of PCV2 in tissue specimens was screened by PCR. Totally, 51.9% samples (173/333) from ten different geographic regions were detected to be positive for PCV2. The PCR-positive samples were further used to amplify PCV2 genomic DNA encompassing the complete ORF2 of PCV2, yielding PCR fragments of 822 or 823 bp. The profiles produced by each endonuclease were shown in Fig. 1. By RFLP analysis of the amplified fragments, 9 different RFLP patterns of PCV2 ORF2 gene were identified and

Discussion

To date, a lot of PCV2 isolates were characterized worldwide (de Boisseson et al., 2004). ORF2 of PCV2 is believed to encode the putative capsid protein, the major structural protein with a molecular mass of 30 kDa (Nawagitgul et al., 2000) and found to be highly variable (Fenaux et al., 2000). Therefore, it is available for ORF2 gene of PCV2 as target fragment within the genome of PCV2, which is used for molecular epidemiological study. Previous literature reported that PCV2 in Canada could be

Acknowledgement

This research was supported by a grant from the Ministry of Education of China.

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Short communicationGenotyping of porcine circovirus type 2 from a variety of clinical conditions in China

Abstract

Introduction

Section snippets

Materials and methods

Results

Discussion

Acknowledgement

Virus Res.

J. Comp. Pathol.

Isolation of porcine circovirus-like viruses from pigs with a wasting disease in the USA and Europe

J. Vet. Diagn. Invest.

Molecular characterization of porcine circovirus type 2 isolates from post-weaning multisystemic wasting syndrome-affected and non-affected pigs

J. Gen. Virol.

Isolation of circovirus from lesions of pigs with postweaning multisystemic wasting syndrome

Can. Vet. J.

J. Clin. Microbiol.

Nucleotide sequence of porcine circovirus associated with postweaning multisystemic wasting syndrome in pigs

J. Virol.

PCR detection and characterization of type-2 porcine circovirus

Can. J. Vet. Res.

Recognizing and diagnosing postweaning multisystemic wasting syndrome (PMWS)

Swine Health Prod.

Detection of porcine circovirus type 2 by PCR

Chin. J. Vet. Sci.

Short communication
Genotyping of porcine circovirus type 2 from a variety of clinical conditions in China