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Prevalence of swine Torque teno virus genogroups 1 and 2 in Japanese swine with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease complex
Veterinary Microbiology 139 (2009) 347–350
Contents lists available at ScienceDirect
Veterinary Microbiology journal homepage: www.elsevier.com/locate/vetmic
Short communication
Prevalence of swine Torque teno virus genogroups 1 and 2 in Japanese swine with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease complex Osamu Taira *, Hirohito Ogawa, Aki Nagao, Kotaro Tuchiya, Tetsuo Nunoya, Susumu Ueda Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 15 April 2009 Received in revised form 27 May 2009 Accepted 3 June 2009
Torque teno virus (TTV) was first isolated from a human hepatitis patient in 1997. TTV was also identified in several animals, including pigs, cattle, sheep, cats and dogs. In this study, we analysed the prevalence of swine TTV genogroups 1 (TTV1) and 2 (TTV2) in Japanese swine populations with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease by using a nested polymerase chain reaction method. Of 153 serum samples from 16 different herds in Japan, TTV1 was detected in 46 samples (30%), TTV2 in 47 samples (31%) and both in 15 samples (10%). There was no significant difference in the detection rate among geographical regions. The overall prevalence rate of TTV genogroups was significantly lower in 30-day-old pigs (11%) compared to that in older age groups (54–82%). These results suggest that swine TTV may be widespread in post-weaning pigs and could play aetiological roles in pig diseases in Japan. This is the first report on the prevalence of swine TTV in Japan. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Torque teno virus Swine Prevalence
1. Introduction Torque teno virus (TTV) was first isolated in Japan in 1997 from a patient with post-transfusion hepatitis of unknown aetiology (Nishizawa et al., 1997). TTV is a small non-enveloped spherical virus with a diameter of 30– 32 nm; it has a single-stranded, negative-sense, circular DNA genome (Itoh et al., 2000; Okamoto et al., 2002). Although the pathological roles of TTV have not yet been clarified, high prevalence rates of TTV DNA were found in patients with haemophilia (67–75%), intravenous drug users (40%) and haemodialysis patients (46%) (Okamoto et al., 1998b; Takayama et al., 1999). Recently, several reports suggested that the prevalence of TTV infection is more prevalent in patients infected HIV (Christensen et al., 2000; Shieh et al., 2003). The mode of transmission of TTV
* Corresponding author. Tel.: +81 428 33 1044; fax: +81 428 31 6166. E-mail address: [email protected] (O. Taira). 0378-1135/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2009.06.010
is not known; however, detection of virus genes in faeces and influent as well as effluent water samples from wastewater treatment plants (Okamoto et al., 1998a; Haramoto et al., 2008) suggests enteric transmission of the virus. On the other hand, the TTV genome has been detected in several domestic animals, including pigs, cattle, sheep, cats and dogs (Leary et al., 1999; Okamoto et al., 2002). Analysis of complete genomic sequences of swine TTVs has revealed 2 TTV genogroups (Okamoto et al., 2002). TTV genogroup 1 (TTV1) is widely distributed in several countries, including USA, Canada, China, Thailand, Korea, Italy, France and Spain, with prevalences ranging from 24% to 100% (McKeown et al., 2004; Bigarre et al., 2005; Martelli et al., 2006). TTV genogroup 2 (TTV2) is more frequently related to post-weaning multisystemic wasting syndrome (PMWS) compared to TTV1 in Spain (77% prevalence) (Kekarainen et al., 2006). The pathogenic role of swine TTV is not clear; however, recent reports suggested the association of swine TTV infection with porcine circovirus 2 (PCV2) infection that causes PMWS
O. Taira et al. / Veterinary Microbiology 139 (2009) 347–350
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and porcine dermatitis and nephropathy syndrome (Ellis et al., 2008; Krakowka and Ellis, 2008; Krakowka et al., 2008). Swine TTV is now widespread throughout the world. Prevalence of swine TTV in Japanese pig herds is still unknown. The objective of this study was to determine the prevalence of TTV1 and TTV2 and to assess age- and region-specific prevalence of both genogroups of swine TTV in Japan.
TTV2) were randomly selected and sequenced using the Big Dye Terminator cycle sequence kit (Applied Biosystems Inc.). Nucleotide sequences were aligned with Japanese reference sequences of the swine TTV noncoding region (Okamoto et al., 2002), using Genetyx-Mac version 14.0 (Software Development Co.). Alignments were input into the Clustal W multiple sequence alignment program to produce the phylogenetic tree. Bootstrap values were calculated on 1000 replicates of the alignment.
2. Materials and methods 3. Results and discussion In 2008, serum samples were collected from 153 pigs in 16 prefectures in Japan. These pigs exhibited clinical symptoms of PMWS or porcine respiratory disease complex (PRDC), but diagnoses for the diseases based on PCV2 infection and histopathology were not defined in the pigs. The geographic origins of sampled pigs are listed in Table 1. These samples were collected from 1- to 5month-old pigs and sows (Table 2). DNA was extracted from the samples using the QIAamp DNA blood mini kit (Qiagen Inc.) according to the manufacturer’s instructions. Polymerase chain reaction (PCR) and nested PCR (nPCR) techniques for TTV1 and TTV2 were performed using a published method (Kekarainen et al., 2006). Twenty positive samples (10 from TTV1 and 10 from
In previous reports, prevalence of TTV in pigs varied from 24% to 100% in several countries (McKeown et al., 2004; Bigarre et al., 2005; Kekarainen et al., 2006; Martelli et al., 2006). In this study, a total of 153 swine serum samples were examined by the nPCR assay. As shown in Table 1, 78/153 (51%) were positive for TTV1 or TTV2. Positive results were observed in 46/153 (30%) for TTV1 and 47/153 (31%) for TTV2. Co-infection of both genogroups of TTV was detected in 15/153 (10%). Homologies of nucleotide sequences within TTV1 and TTV2 were 89– 98% and 91–98%, respectively. Although both TTV1 and TTV2 were found in Japan, no genogroup-specific geographical distribution was observed (Fig. 1). The presence
Table 1 Prevalence of swine TTV genogroups in different areas in Japan. Prefecture
Prevalence of swine TTV genogroup Genogroup 1 or 2
Genogroup 1
Genogroup 2
Genogroups 1 and 2
Hokkaido (n = 2) Gunma (n = 12) Tochigi (n = 10) Ibaraki (n = 10) Chiba (n = 8) Tokyo (n = 12) Nagano (n = 12) Shizuoka (n = 6) Aichi (n = 6) Hiroshima (n = 12) Tokushima (n = 8) Ehime (n = 12) Oita (n = 10) Kumamoto (n = 12) Miyazaki (n = 9) Kagoshima (n = 12)
0/2 (0%)a 8/12 (67%) 4/10 (40%) 8/10 (80%) 5/8 (63%) 5/12 (42%) 6/12 (50%) 0/6 (0%) 6/6 (100%) 7/12 (58%) 4/8 (50%) 2/12 (17%) 7/10 (70%) 6/12 (50%) 3/9 (33%) 7/12 (58%)
0/2 (0%) 4/12 (33%) 1/10 (10%) 3/10 (30%) 3/8 (38%) 4/12 (33%) 5/12 (42%) 0/6 (0%) 4/6 (67%) 5/12 (42%) 2/8 (38%) 1/12 (8%) 5/10 (50%) 5/12 (42%) 2/9 (22%) 2/12 (25%)
0/2 (0%) 6/12 (50%) 3/10 (30%) 8/10 (80%) 2/8 (25%) 1/12 (8%) 2/12 (17%) 0/6 (0%) 3/6 (50%) 3/12 (25%) 2/8 (13%) 1/12 (8%) 5/10 (50%) 4/12 (33%) 1/9 (11%) 6/12 (42%)
0/2 (0%) 2/12 (17%) 0/10 (0%) 3/10 (30%) 0/8 (0%) 0/12 (0%) 1/12 (8%) 0/6 (0%) 1/6 (17%) 1/12 (8%) 0/8 (0%) 0/12 (0%) 3/10 (30%) 3/12 (25%) 0/9 (0%) 1/12 (8%)
Total (n = 153)
78/153 (51%)
46/153 (30%)
47/153 (31%)
15/153 (10%)
a
Number of positive animals/total animals examined (%).
Table 2 Prevalence of swine TTV genogroups at different ages. Age (days)
Prevalence of swine TTV genogroup Genogroup 1 or 2 a
Genogroup 1
Genogroup 2
Genogroups 1 and 2
30 (n = 37) 60 (n = 22) 90 (n = 22) 120 (n = 24) 150 (n = 22) Sows (n = 26)
4/37 (11%) 12/22 (55%) 15/22 (68%) 15/24 (63%) 18/22 (82%) 14/26 (54%)
4/37 (11%) 8/22 (36%) 1/22 (5%) 10/24 (42%) 11/22 (50%) 12/26 (46%)
0/37 (0%) 6/22 (27%) 14/22 (64%) 11/24 (46%) 14/22 (64%) 2/26 (8%)
0/37 2/22 0/22 6/24 7/22 0/26
Total (n = 153)
78/153 (51%)
46/153 (30%)
47/153 (31%)
15/153 (10%)
a
Number of positive animals/total animals examined (%).
(0%) (9%) (0%) (25%) (32%) (0%)
O. Taira et al. / Veterinary Microbiology 139 (2009) 347–350
349
Fig. 1. Phylogenetic analysis of swine Torque teno virus (TTV) non-coding region. Trees were generated by the nearest neighbour-joining method. Designations of the genogroups are indicated on the right. Japanese swine TTV1 (AY823991) and TTV2 (AB076001) prototype sequences are indicated in bold letters. Bootstrap values are >50% values only.
of swine TTV in both PMWS-affected and non-PMWSaffected pigs in Spain was reported (Kekarainen et al., 2006); no significant difference was observed in the prevalence rate of TTV genotypes (72/121 [60%] of TTV1 and 93/121 [77%] of TTV2, respectively), although TTV2 was more strongly correlated with PMWS-affected pigs compared to TTV1. In the present study, the pigs from which serum samples were collected were suspected with clinical PMWS; however, no aetiological examinations were conducted. While the results showed overall prevalence of TTV in Japan, the exact relationship between swine TTV and PMWS was not clear from our study. As shown in Table 2, both TTV1 and TTV2 were found in all age groups, except in 30-day-old pigs in whom TTV2 was not detected. The prevalence rate of TTV1 was higher in 60(36%), 120- (42%) and 150-day-old (50%) pigs and sows (46%) compared to 30- (11%) and 90-day-old (5%) pigs. On the other hand, TTV2 showed higher prevalence in 90(64%), 120- (46%) and 150-day-old (64%) pigs compared to 60-day-old (27%) pigs and sows (8%). In humans, TTV prevalence showed a tendency to increase with age (Salakova et al., 2004); however, such age difference in swine TTV infection was not observed in our results. Regardless, both TTV genogroups, TTV2 in particular, appeared to spread to the pigs comparatively soon postweaning because the prevalence in 30-day-old pigs was low (or 0%).
In conclusion, the results of the present study showed ubiquitous distribution of TTV in Japanese swine. Further studies on the detailed pathogenicity of TTV in pigs, including the relationship between the virus and PMWS and PRDC, are needed. References Bigarre, L., Beven, V., de Boisseson, C., Grasland, B., Rose, N., Biagini, P., Jestin, A., 2005. Pig anelloviruses are highly prevalent in swine herds in France. J. Gen. Virol. 86, 631–635. Christensen, J.K., Eugen-Olsen, J.M., Sorensen, M., Ullum, H., Gjedde, S.B., Pedersen, B.K., Nielsen, J.O., Krogsgaard, K., 2000. Prevalence and prognostic significance of infection with TT virus in patients infected with human immunodeficiency virus. J. Infect. Dis. 181, 1796–1799. Ellis, J.A., Allan, G., Krakowka, S., 2008. Effect of coinfection with genogroup 1 porcine torque teno virus on porcine circovirus type 2associated postweaning multisystemic wasting syndrome in gnotobiotic pigs. Am. J. Vet. Res. 69, 1608–1614. Haramoto, E., Katayama, H., Ohgaki, S., 2008. Quantification and genotyping of torque teno virus at a wastewater treatment plant in Japan. Appl. Environ. Microbiol. 74, 7434–7436. Itoh, Y., Takahashi, M., Fukuda, M., Shibayama, T., Ishikawa, T., Tsuda, F., Tanaka, T., Nishizawa, T., Okamoto, H., 2000. Visualization of TT virus particles recovered from the sera and feces of infected humans. Biochem. Biophys. Res. Commun. 279, 718–724. Kekarainen, T., Sibila, M., Segales, J., 2006. Prevalence of swine Torque teno virus in post-weaning multisystemic wasting syndrome (PMWS)-affected and non-PMWS-affected pigs in Spain. J. Gen. Virol. 87, 833–837. Krakowka, S., Ellis, J.A., 2008. Evaluation of the effects of porcine genogroup 1 torque teno virus in gnotobiotic swine. Am. J. Vet. Res. 69, 1623–1629.
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Krakowka, S., Hartunian, C., Hamberg, A., Shoup, D., Rings, M., Zhang, Y., Allan, G., Ellis, J.A., 2008. Evaluation of induction of porcine dermatitis and nephropathy syndrome in gnotobiotic pigs with negative results for porcine circovirus type 2. Am. J. Vet. Res. 69, 1615–1622. Leary, T.P., Erker, J.C., Chalmers, M.L., Desai, S.M., Mushahwar, I.K., 1999. Improved detection systems for TT virus reveal high prevalence in humans, non-human primates and farm animals. J. Gen. Virol. 80 (Pt 8), 2115–2120. Martelli, F., Caprioli, A., Di Bartolo, I., Cibin, V., Pezzotti, G., Ruggeri, F.M., Ostanello, F., 2006. Detection of swine torque teno virus in Italian pig herds. J. Vet. Med. B: Infect. Dis. Vet. Public Health 53, 234–238. McKeown, N.E., Fenaux, M., Halbur, P.G., Meng, X.J., 2004. Molecular characterization of porcine TT virus, an orphan virus, in pigs from six different countries. Vet. Microbiol. 104, 113–117. Nishizawa, T., Okamoto, H., Konishi, K., Yoshizawa, H., Miyakawa, Y., Mayumi, M., 1997. A novel DNA virus (TTV) associated with elevated transaminase levels in posttransfusion hepatitis of unknown etiology. Biochem. Biophys. Res. Commun. 241, 92–97. Okamoto, H., Akahane, Y., Ukita, M., Fukuda, M., Tsuda, F., Miyakawa, Y., Mayumi, M., 1998a. Fecal excretion of a nonenveloped DNA virus
(TTV) associated with posttransfusion non-A–G hepatitis. J. Med. Virol. 56, 128–132. Okamoto, H., Nishizawa, T., Kato, N., Ukita, M., Ikeda, H., Iizuka, H., Miyakawa, Y., Mayumi, M., 1998b. Molecular cloning and characterization of a novel DNA virus (TTV) associated with posttransfusion hepatitis of unknown etiology. Hepatol. Res. 10, 1–16. Okamoto, H., Takahashi, M., Nishizawa, T., Tawara, A., Fukai, K., Muramatsu, U., Naito, Y., Yoshikawa, A., 2002. Genomic characterization of TT viruses (TTVs) in pigs, cats and dogs and their relatedness with species-specific TTVs in primates and tupaias. J. Gen. Virol. 83, 1291– 1297. Salakova, M., Nemecek, V., Konig, J., Tachezy, R., 2004. Age-specific prevalence, transmission and phylogeny of TT virus in the Czech Republic. BMC Infect. Dis. 4, 56. Shieh, B., Chang, M.J., Ko, W.C., Chen, E.J., Wu, J.C., Lee, C.F., Chang, T.T., Li, C., 2003. Effects of multiple virus coinfections on disease progression in HIV-positive patients. Intervirology 46, 105–113. Takayama, S., Miura, T., Matsuo, S., Taki, M., Sugii, S., 1999. Prevalence and persistence of a novel DNA TT virus (TTV) infection in Japanese haemophiliacs. Br. J. Haematol. 104, 626–629.
Contents lists available at ScienceDirect
Veterinary Microbiology journal homepage: www.elsevier.com/locate/vetmic
Short communication
Prevalence of swine Torque teno virus genogroups 1 and 2 in Japanese swine with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease complex Osamu Taira *, Hirohito Ogawa, Aki Nagao, Kotaro Tuchiya, Tetsuo Nunoya, Susumu Ueda Nippon Institute for Biological Science, 9-2221-1 Shinmachi, Ome, Tokyo 198-0024, Japan
A R T I C L E I N F O
A B S T R A C T
Article history: Received 15 April 2009 Received in revised form 27 May 2009 Accepted 3 June 2009
Torque teno virus (TTV) was first isolated from a human hepatitis patient in 1997. TTV was also identified in several animals, including pigs, cattle, sheep, cats and dogs. In this study, we analysed the prevalence of swine TTV genogroups 1 (TTV1) and 2 (TTV2) in Japanese swine populations with suspected post-weaning multisystemic wasting syndrome and porcine respiratory disease by using a nested polymerase chain reaction method. Of 153 serum samples from 16 different herds in Japan, TTV1 was detected in 46 samples (30%), TTV2 in 47 samples (31%) and both in 15 samples (10%). There was no significant difference in the detection rate among geographical regions. The overall prevalence rate of TTV genogroups was significantly lower in 30-day-old pigs (11%) compared to that in older age groups (54–82%). These results suggest that swine TTV may be widespread in post-weaning pigs and could play aetiological roles in pig diseases in Japan. This is the first report on the prevalence of swine TTV in Japan. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Torque teno virus Swine Prevalence
1. Introduction Torque teno virus (TTV) was first isolated in Japan in 1997 from a patient with post-transfusion hepatitis of unknown aetiology (Nishizawa et al., 1997). TTV is a small non-enveloped spherical virus with a diameter of 30– 32 nm; it has a single-stranded, negative-sense, circular DNA genome (Itoh et al., 2000; Okamoto et al., 2002). Although the pathological roles of TTV have not yet been clarified, high prevalence rates of TTV DNA were found in patients with haemophilia (67–75%), intravenous drug users (40%) and haemodialysis patients (46%) (Okamoto et al., 1998b; Takayama et al., 1999). Recently, several reports suggested that the prevalence of TTV infection is more prevalent in patients infected HIV (Christensen et al., 2000; Shieh et al., 2003). The mode of transmission of TTV
* Corresponding author. Tel.: +81 428 33 1044; fax: +81 428 31 6166. E-mail address: [email protected] (O. Taira). 0378-1135/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.vetmic.2009.06.010
is not known; however, detection of virus genes in faeces and influent as well as effluent water samples from wastewater treatment plants (Okamoto et al., 1998a; Haramoto et al., 2008) suggests enteric transmission of the virus. On the other hand, the TTV genome has been detected in several domestic animals, including pigs, cattle, sheep, cats and dogs (Leary et al., 1999; Okamoto et al., 2002). Analysis of complete genomic sequences of swine TTVs has revealed 2 TTV genogroups (Okamoto et al., 2002). TTV genogroup 1 (TTV1) is widely distributed in several countries, including USA, Canada, China, Thailand, Korea, Italy, France and Spain, with prevalences ranging from 24% to 100% (McKeown et al., 2004; Bigarre et al., 2005; Martelli et al., 2006). TTV genogroup 2 (TTV2) is more frequently related to post-weaning multisystemic wasting syndrome (PMWS) compared to TTV1 in Spain (77% prevalence) (Kekarainen et al., 2006). The pathogenic role of swine TTV is not clear; however, recent reports suggested the association of swine TTV infection with porcine circovirus 2 (PCV2) infection that causes PMWS
O. Taira et al. / Veterinary Microbiology 139 (2009) 347–350
348
and porcine dermatitis and nephropathy syndrome (Ellis et al., 2008; Krakowka and Ellis, 2008; Krakowka et al., 2008). Swine TTV is now widespread throughout the world. Prevalence of swine TTV in Japanese pig herds is still unknown. The objective of this study was to determine the prevalence of TTV1 and TTV2 and to assess age- and region-specific prevalence of both genogroups of swine TTV in Japan.
TTV2) were randomly selected and sequenced using the Big Dye Terminator cycle sequence kit (Applied Biosystems Inc.). Nucleotide sequences were aligned with Japanese reference sequences of the swine TTV noncoding region (Okamoto et al., 2002), using Genetyx-Mac version 14.0 (Software Development Co.). Alignments were input into the Clustal W multiple sequence alignment program to produce the phylogenetic tree. Bootstrap values were calculated on 1000 replicates of the alignment.
2. Materials and methods 3. Results and discussion In 2008, serum samples were collected from 153 pigs in 16 prefectures in Japan. These pigs exhibited clinical symptoms of PMWS or porcine respiratory disease complex (PRDC), but diagnoses for the diseases based on PCV2 infection and histopathology were not defined in the pigs. The geographic origins of sampled pigs are listed in Table 1. These samples were collected from 1- to 5month-old pigs and sows (Table 2). DNA was extracted from the samples using the QIAamp DNA blood mini kit (Qiagen Inc.) according to the manufacturer’s instructions. Polymerase chain reaction (PCR) and nested PCR (nPCR) techniques for TTV1 and TTV2 were performed using a published method (Kekarainen et al., 2006). Twenty positive samples (10 from TTV1 and 10 from
In previous reports, prevalence of TTV in pigs varied from 24% to 100% in several countries (McKeown et al., 2004; Bigarre et al., 2005; Kekarainen et al., 2006; Martelli et al., 2006). In this study, a total of 153 swine serum samples were examined by the nPCR assay. As shown in Table 1, 78/153 (51%) were positive for TTV1 or TTV2. Positive results were observed in 46/153 (30%) for TTV1 and 47/153 (31%) for TTV2. Co-infection of both genogroups of TTV was detected in 15/153 (10%). Homologies of nucleotide sequences within TTV1 and TTV2 were 89– 98% and 91–98%, respectively. Although both TTV1 and TTV2 were found in Japan, no genogroup-specific geographical distribution was observed (Fig. 1). The presence
Table 1 Prevalence of swine TTV genogroups in different areas in Japan. Prefecture
Prevalence of swine TTV genogroup Genogroup 1 or 2
Genogroup 1
Genogroup 2
Genogroups 1 and 2
Hokkaido (n = 2) Gunma (n = 12) Tochigi (n = 10) Ibaraki (n = 10) Chiba (n = 8) Tokyo (n = 12) Nagano (n = 12) Shizuoka (n = 6) Aichi (n = 6) Hiroshima (n = 12) Tokushima (n = 8) Ehime (n = 12) Oita (n = 10) Kumamoto (n = 12) Miyazaki (n = 9) Kagoshima (n = 12)
0/2 (0%)a 8/12 (67%) 4/10 (40%) 8/10 (80%) 5/8 (63%) 5/12 (42%) 6/12 (50%) 0/6 (0%) 6/6 (100%) 7/12 (58%) 4/8 (50%) 2/12 (17%) 7/10 (70%) 6/12 (50%) 3/9 (33%) 7/12 (58%)
0/2 (0%) 4/12 (33%) 1/10 (10%) 3/10 (30%) 3/8 (38%) 4/12 (33%) 5/12 (42%) 0/6 (0%) 4/6 (67%) 5/12 (42%) 2/8 (38%) 1/12 (8%) 5/10 (50%) 5/12 (42%) 2/9 (22%) 2/12 (25%)
0/2 (0%) 6/12 (50%) 3/10 (30%) 8/10 (80%) 2/8 (25%) 1/12 (8%) 2/12 (17%) 0/6 (0%) 3/6 (50%) 3/12 (25%) 2/8 (13%) 1/12 (8%) 5/10 (50%) 4/12 (33%) 1/9 (11%) 6/12 (42%)
0/2 (0%) 2/12 (17%) 0/10 (0%) 3/10 (30%) 0/8 (0%) 0/12 (0%) 1/12 (8%) 0/6 (0%) 1/6 (17%) 1/12 (8%) 0/8 (0%) 0/12 (0%) 3/10 (30%) 3/12 (25%) 0/9 (0%) 1/12 (8%)
Total (n = 153)
78/153 (51%)
46/153 (30%)
47/153 (31%)
15/153 (10%)
a
Number of positive animals/total animals examined (%).
Table 2 Prevalence of swine TTV genogroups at different ages. Age (days)
Prevalence of swine TTV genogroup Genogroup 1 or 2 a
Genogroup 1
Genogroup 2
Genogroups 1 and 2
30 (n = 37) 60 (n = 22) 90 (n = 22) 120 (n = 24) 150 (n = 22) Sows (n = 26)
4/37 (11%) 12/22 (55%) 15/22 (68%) 15/24 (63%) 18/22 (82%) 14/26 (54%)
4/37 (11%) 8/22 (36%) 1/22 (5%) 10/24 (42%) 11/22 (50%) 12/26 (46%)
0/37 (0%) 6/22 (27%) 14/22 (64%) 11/24 (46%) 14/22 (64%) 2/26 (8%)
0/37 2/22 0/22 6/24 7/22 0/26
Total (n = 153)
78/153 (51%)
46/153 (30%)
47/153 (31%)
15/153 (10%)
a
Number of positive animals/total animals examined (%).
(0%) (9%) (0%) (25%) (32%) (0%)
O. Taira et al. / Veterinary Microbiology 139 (2009) 347–350
349
Fig. 1. Phylogenetic analysis of swine Torque teno virus (TTV) non-coding region. Trees were generated by the nearest neighbour-joining method. Designations of the genogroups are indicated on the right. Japanese swine TTV1 (AY823991) and TTV2 (AB076001) prototype sequences are indicated in bold letters. Bootstrap values are >50% values only.
of swine TTV in both PMWS-affected and non-PMWSaffected pigs in Spain was reported (Kekarainen et al., 2006); no significant difference was observed in the prevalence rate of TTV genotypes (72/121 [60%] of TTV1 and 93/121 [77%] of TTV2, respectively), although TTV2 was more strongly correlated with PMWS-affected pigs compared to TTV1. In the present study, the pigs from which serum samples were collected were suspected with clinical PMWS; however, no aetiological examinations were conducted. While the results showed overall prevalence of TTV in Japan, the exact relationship between swine TTV and PMWS was not clear from our study. As shown in Table 2, both TTV1 and TTV2 were found in all age groups, except in 30-day-old pigs in whom TTV2 was not detected. The prevalence rate of TTV1 was higher in 60(36%), 120- (42%) and 150-day-old (50%) pigs and sows (46%) compared to 30- (11%) and 90-day-old (5%) pigs. On the other hand, TTV2 showed higher prevalence in 90(64%), 120- (46%) and 150-day-old (64%) pigs compared to 60-day-old (27%) pigs and sows (8%). In humans, TTV prevalence showed a tendency to increase with age (Salakova et al., 2004); however, such age difference in swine TTV infection was not observed in our results. Regardless, both TTV genogroups, TTV2 in particular, appeared to spread to the pigs comparatively soon postweaning because the prevalence in 30-day-old pigs was low (or 0%).
In conclusion, the results of the present study showed ubiquitous distribution of TTV in Japanese swine. Further studies on the detailed pathogenicity of TTV in pigs, including the relationship between the virus and PMWS and PRDC, are needed. References Bigarre, L., Beven, V., de Boisseson, C., Grasland, B., Rose, N., Biagini, P., Jestin, A., 2005. Pig anelloviruses are highly prevalent in swine herds in France. J. Gen. Virol. 86, 631–635. Christensen, J.K., Eugen-Olsen, J.M., Sorensen, M., Ullum, H., Gjedde, S.B., Pedersen, B.K., Nielsen, J.O., Krogsgaard, K., 2000. Prevalence and prognostic significance of infection with TT virus in patients infected with human immunodeficiency virus. J. Infect. Dis. 181, 1796–1799. Ellis, J.A., Allan, G., Krakowka, S., 2008. Effect of coinfection with genogroup 1 porcine torque teno virus on porcine circovirus type 2associated postweaning multisystemic wasting syndrome in gnotobiotic pigs. Am. J. Vet. Res. 69, 1608–1614. Haramoto, E., Katayama, H., Ohgaki, S., 2008. Quantification and genotyping of torque teno virus at a wastewater treatment plant in Japan. Appl. Environ. Microbiol. 74, 7434–7436. Itoh, Y., Takahashi, M., Fukuda, M., Shibayama, T., Ishikawa, T., Tsuda, F., Tanaka, T., Nishizawa, T., Okamoto, H., 2000. Visualization of TT virus particles recovered from the sera and feces of infected humans. Biochem. Biophys. Res. Commun. 279, 718–724. Kekarainen, T., Sibila, M., Segales, J., 2006. Prevalence of swine Torque teno virus in post-weaning multisystemic wasting syndrome (PMWS)-affected and non-PMWS-affected pigs in Spain. J. Gen. Virol. 87, 833–837. Krakowka, S., Ellis, J.A., 2008. Evaluation of the effects of porcine genogroup 1 torque teno virus in gnotobiotic swine. Am. J. Vet. Res. 69, 1623–1629.
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