Pesq. Vet. Bras. 33(7):840-846, julho 2013
Torque teno sus virus (TTSuV) infection at different stages of pig production cycle1
Raquel de A. Leme2 2 2*
ABSTRACT.- , Alice F. Alfieri and AmauriTorque tenoA. Alfieri sus virus (TTSuV) infection at different stages of pig production cycle. Pesquisa Veterinária Brasileira 33(7):840-846.Leme Laboratório R.A., Alfieri de VirologiaA.F. & Alfieri Animal, A.A. Departamento2013. de Medicina Veterinária Preventiva, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid, Campus Univer- sitário, Cx. Postal Londrina, PR 86057-970, Brazil E-mail: Torque teno sus virus (TTSuV) infection is present in pig herds worldwide. It has been demonstrated that10011, TTSuV might increase the severity of other [email protected] viral diseases with economic and public health impacts. At present, there is no information on the age distribution of pigs infected with TTSuV in Brazilian herds. This study evaluated the fre- quency of TTSuV infection in pigs at different stages of production. Fecal samples (n
=190) from pigs at 1 to 24 weeks of age and from breeders at 6 farrow-to-weaning (up to 8 weeks of age) and 9 grower-to-finish (9 weeks of age onwards) farms in the western region of- Paraná state, Brazil, were evaluated by PCR. Fragments of the 5’ UTRs of TTSuV1 and/or infectionsTTSuVk2 DNAsby both were genera identified between in 126 and (66.3%) within theof the different fecal samples. pig production Significant stages. differen Fecal ces were found with the percentages of positive samples for TTSuV1, TTSuVk2, and mixed
samples from the grower-to-finish farms had TTSuV detection rates (90.1%; 64/71) that inwere the significantly animals from (p<0.05) the other higher stages. than The those UTR fromnucleotide the farrow-to-weaning sequences in this farms study (52.1%;presen- 62/119). TTSuV detection was significantly (p<0.05) more frequent in finisher pigs than
productionted higher similaritiesstages and thatto strains the viral from infection Norway rate (96%, increases TTSuV1), with andthe ageArgentina of the animals. and China In (97.1%, TTSuVk2). These results suggest that TTSuV infection has spread to pigs of all
the western region of Paraná state, Brazil, TTSuV1 and TTSuVk2-induced infections were inmore pig frequentlyherds of Brazil. observed in suckling piglets and finisher pigs, respectively. Phylogenetic analysis pointed out the possibility of different strains of TTSuV1 and TTSuVk2 circulating Torque teno sus virus, Iotatorquevirus, Kappatorquevirus distribution, PCR, swine. INDEX TERMS: , TTSuV1 and TTSuVk2, age RESUMO.- [Infecção pelo Torque teno sus virus (TTSuV) há informações sobre a distribuição da infecção pelo TT- em diferentes categorias do ciclo de produção de su- SuV, de acordo com a faixa etária, em rebanhos suinícolas ínos.] A infecção pelo Torque teno sus virus (TTSuV) está brasileiros. Este estudo avaliou a frequência da infecção presente em rebanhos suinícolas em todo o mundo. Tem pelo TTSuV nas diferentes categorias de produção de suí- sido demonstrado que a infecção pelo TTSuV pode aumen- nos. Amostras fecais (n - tar a gravidade de outras importantes doenças virais com nas de idade e de reprodutores provenientes 6 unidades impactos econômicos e na saúde pública. Atualmente não produtoras de leitão (até=190) 8 semanas de suínos de idade) com 1 e a9 24unidades sema de terminação (9 semanas de idade em diante) da região oeste do Paraná, Brasil, foram avaliadas pela técnica de 1 2 LaboratórioReceived on deFebruary Virologia 7, 2013.Animal, Departamento de Medicina Veteriná- ria Preventiva,Accepted for Universidade publication on Estadual April 11, de 2013. Londrina (UEL), Rodovia Celso PCR. Fragmentos da região 5’ UTR do DNA do TTSuV1 e/- 970, Brazil. *Corresponding author: ou TTSuVk2 foram identificados em 126 (66,3%) amostras Garcia Cid, Campus Universitário, Cx. Postal 10011, Londrina, PR 86057- fecais. Diferenças significativas foram encontradas em rela [email protected] ção às porcentagens de amostras positivas para o TTSuV1, 840 Torque teno sus virus (TTSuV) infection at different stages of pig production cycle
841 - - tra categorias. Amostras fecais provenientes de unidades Leme et deTTSuVk2 terminação e infecção apresentaram mista por taxasambos de os detecção gêneros deinter TTSuV e in systems). are specific research tools that are not well estab lishedStudies for this have virus demonstrated (Kekarainen the & Segaléspresence 2009, of TTSuV in que aquelas provenientes de unidades produtoras de leitão al. 2012 - (90.1%; 64/71) significativamente (p<0.05) mais altas do- increasesthe serum with and the organs age of of the pigs animals of different (Sibila ages et al. (Kekara 2009b, que(52.1%; nos 62/119).suínos de A outras detecção categorias. do TTSuV As emsequências animais de ternu- inen & Segalés 2012) and have shown that the prevalence cleotídeosminação foi da significativamente UTR deste estudo (p<0.05) apresentaram mais frequente maior simi do- - Aramouni et al. 2010). In Brazil, TTSuV infection has been identified in suckling piglets (Leme et al. 2012) and slaugh alaridade infecção com pelo cepas TTSuV da Noruegaencontra-se (96%, disseminada TTSuV1) e emArgentina suínos theseter-age studies, pigs (Leme no information et al. 2013), is available and in relative the reproductive to the age dee China todas (97,1%, as categorias TTSuVk2). de produção Estes resultados e que a taxasugerem da infec que- distributiontracts of boars of andTTSuV sows infection (Ritterbusch throughout et al. 2012). the Brazilian Despite pig production system. região oeste do estado do Paraná, infecções induzidas pelo The aims of this study were to evaluate natural infection ção viral aumenta de acordo com a idade dos animais. Na- das em leitões de maternidade e suínos de terminação, evaluate the frequency of TTSuV infection at different sta- TTSuV1 e TTSuVk2 foram mais frequentemente observa- gesby TTSuV of pig production.in 1 to 24 week-old pigs and in breeders, and to emrespectivamente. rebanhos suinícolas A análise brasileiros. filogenética indicou a possibili MATERIALS AND METHODS dade de diferentes cepas de TTSuV1 e TTSuVk2 circulando Torque teno sus virus, Iotatorquevirus, One hundred and ninety fecal samples of pigs from the western Kappatorquevirus region of Paraná state, Brazil, were included in this study. The PCR,TERMOS suínos. DE INDEXAÇÃO: samples were selected independent of their consistency (diar- , TTSuV1 e TTSuVk2, distribuição por idade, INTRODUCTION Six farrow-to-weaning farms, which include breeder sows and bo- rheic or not), collected between 2008 and 2011, and stored at 4°C. Torque teno virus (TTV) is a non-enveloped virus with a - ars, suckling piglets, and weaned pigs up to 8 weeks of age, and nine grower-to-finish farms, where 9-week-old pigs are housed circular negative-sense single-stranded DNA (ssDNA) ge and fed until they reach 24 weeks of age, were evaluated. A total of nome. This virus was first isolated from a Japanese man 119Fecal fecal samplessamples fromfor each farrow-to-weaning of the pig production farms and stages 71 samples were with non A-E post-transfusional hepatitis (Nishizawa et al. from grower-to-finish farms were selected. n - 1997). Since then, TTV has been shown to infect humans, n non-humanTorque teno primates, sus virus and farm(TTSuV) animals infection (Leary in et pigs al. 1999, was nanalyzed: suckling pigletsn (1 to 3 weeks old, =35), weaned pi Okamoto et al. 2000, 2001, 2002, Brassard et al. 2008). glets (4 to 8 weeks old, =43), finisher pigs (9 to 24 weeks old, =71), and breeders ( =41). 5,000Fecal x g suspensions were prepared at 10 to 20% (w/v) in 0.01- first described by Leary et al. (1999). The first full genome and the differentiation of TTSuV into separate species was tion.M phosphate-buffered saline (PBS), pH 7.2, and centrifuged at analysis of TTSuV was completed by Okamoto et al. (2002),- for 3 min. The supernatants were used for DNA extrac ly Anelloviridae performed by Niel et al. (2005). TTSuV belongs to the fami- To determine the frequency of TTSuV infection, viral ssDNA and is classified into theIotatorquevirus species TTSuV1a, and was extracted by using a combination of the phenol/chloroform/- (represented by Sd-TTV31 strain) and TTSuV1b (represen mediatelyisoamyl alcohol submitted (25:24:1) to a polymerase and silica/guanidinium chain reaction isothiocyanate (PCR) assay. Kappatorquevirusted by Sd-TTV1p strain) in the genus nucleic acid extraction methods (Alfieri et al. 2006) and was im TTSuVk2TTSuV (representedis widely distributed by Sd-TTV2p in pig strain) herds in thea number genus (Iotatorquevirus Kappatorquevirus) targeting the (ICTV 2012). non-codingSpecific PCRregion assays of the were viral performed genome, using and primersthe technique for TTSuV1 was of countries in Asia, Europe, and America (McKeown et al. ) and TTSuVk2 (
performed as described (Segalés et al. 2009), with modifications found2004, Nielin both et al. healthy 2005, andGallei diseased et al. 2010, pigs, Savicand a et number al. 2010, of (Leme et al. 2012). The amplification reaction was performed in studiesPérez et have al. 2011,been performed Leme et al. to 2012). determine TTSuV the infection importan is- a thermocycler (Swift™ MaxPro Thermal Cycler, Esco Healthcare ce of the virus and the role it plays in infectious diseases Pte, Singapore) at 94°C for 5 min for denaturation followed by 40 cycles of 94°C/1 min, 54°C/1 min, and 72°C/1 min and a final The detection of TTSuV infection is currently based on extensionFive at 72°C for 5 min. The expected sizes of the amplified- (Meng 2012). products were 305 and 252 bp for TTSuV1 and k2, respectively. positive samples for TTSuV1 and TTSuVk2 were ran Western blot and indirect ELISA assays to detect TTSuV2- the amplicons obtained in this study. The amplicons were puri- domly selected for sequence analysis to confirm the specificity of conventional and real-time PCR assays. Recently, the first Technologies,fied by using aEugene, QIAquick OR, PCR USA), purification and analyzed Kit by(Qiagen, electrophoresis Valencia, onspecific histopathological IgG antibodies technique in pig serum has werebeen developed discussed (Huang(Mei et CA, USA), quantified with a Qubit™ Fluorometer (Invitrogen™ Life- et al. 2011). The shortage of TTSuV infection studies based- cal and in situ hybridization techniques, and viral culture Fosteron a 2% City, agarose CA, USA) gel. were An ABI3500 used for Geneticsequencing, Analyzer with andforward the Bigand al. 2011). However, serological assays, immunohistochemi Dye™ Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems,
Pesq. Vet. Bras. 33(7):840-846, julho 2013 842
Raquel de A. Leme, Alice F. Alfieri and Amauri A. Alfieri Table 1. Detection rates of TTSuV1 and TTSuVk2 in single and mixed-infections by PCR assay in pig fecal samples according to stage of pig production cycle
detection piglets piglets pigs (♂ ♀ n TTSuV Suckling Weaned Finisher nBreeders Total n n n =10/ =31) =190 (1 to 3 weeks) (4 to 8 weeks) (9 to 24 weeks) =41 (%) A, a A, a 4 (5.6)B, a A, a =35 (%) =43 (%) =71 (%) A, b C, a B, b A, C, a TTSuV1 10 (28.6)A , b 10 (23.3)A, B, a B, c 8 (19.5)A, a 32 (16.8) TTSuVk2Total Positive 3 (8.6) 12 (27.9) 39 (54.9) 5 (12.2) 59 (31) TTSuV1 + k2 3 (8.6) 8 (18.6) 21 (29.5) 3 (7.3) 35 (18.4) 16 (45.7) 30 (69.8) 64 (90.1) 16 (39) 126 (66.3) Capital letters (A, B and C) refer to comparisons between stages and lower case letters (a, b, and c) refer Total Negative 19 (54.3) 13 (30.2) 7 (9.9) 25 (61) 64 (33.7)
to comparisons within each of the stages. Different letters indicate statistically significant differences (p<0.05). reverse primers. Sequence quality analysis was performed using -
ted Allat significantlyfarms evaluated (p<0.05) had positive higher ratesresults than for singleboth TTSuV infec Phred and CAP3 software (http://asparagin.cenargen.embrapa. tions of TTSuV1. br/phph/). Similarity searches were done with similar sequences- condeposited of each in TTSuV GenBank genus by wasusing randomly the Basic selected Local Alignment for phylogenetic Search Tool - BLAST (http://blast.ncbi.nlm.nih.gov/Blast.cgi). One ampli genera. The rates of TTSuV detection were 52.1% (62/119) - and 90.1% (64/71) for samples from farrow-to-weaning analyses, which was performed by using MEGA package (version and grower-to-finish farms, respectively, and the difference 5.10). Two phylogenetic trees based on nucleotide (nt) were ob atbetween all farrow-to-weaning these rates was farmssignificant (n (p<0.05). TTSuV1 and- tained using maximum likelihood statistical method based on- TTSuVk2 were detected in both single and mixed infections- cates.kimura Sequence two-parameter identity (K2+G)matrix was and performed tamura-nei using models, the BioEdit which ms (n =6); for the single infec provided statistical support via bootstrapping with 1,000 repli- tions of TTSuV1 were detected at 4 of grower-to-finish far oedit.html). evaluated=9), whereas(Table 2). single infections of TTSuVk2 and mixed software version 7.1.11 (http://www.mbio.ncsu.edu/bioedit/biTM Statistical analysis was performed with Epi Info , using Chi- infectionsP of TTSuV1+TTSuVk2 were observed in all farms- -square (c²) or Fisher exact tests to compare the proportions of TTSuV-positive samples between and within the pig production tions with both genera were observed throughout the pe- stages and to compare the detection rates of TTSuV of the diffe- ositive results for TTSuV1, TTSuVk2, and mixed infec - riod evaluated (2008-2011). rent farm types (farrow-to-weaning vs. grower-to-finish). The The specificity of the amplicons obtained for each TT confidence limit for the statisticalRESULTS tests was set at 95% (p<0.05). SuV genus was confirmed during the sequence analyses.- The UTR nt sequences of the TTSuV1 (TTSuV1_BRA16/09) positive for TTSuV infection. The TTSuV presence was de- and TTSuVk2 (TTSuV2_BRA26/10) obtained herein con- tectedOf the 190in pigs pig of fecal all stages samples evaluated. evaluated, The 126 TTSuV (66.3%) detection were tain 311 and 252 bp, respectively. Comparisons of the nt- results for each stage of pig producing cycle are presented sequence of the TTSuV1 strain in this study to those avai- lable in GenBank revealed 96% and 95.6% of nt similari Among the pig production stages, single infections of ty to strains from Norway (TTV1_NOR02) and Brazil (TT in Table 1. - sequenceSuV1_BRA11/07), in this study respectively. and the others Slightly from smaller Brazil. similarities (91.3% to 93%) were observed between the TTSuV1 nt- TTSuV1 were significantly (p<0.05) more frequent in su ckling piglets than finisher pigs, and in breeders relative to- Regarding the TTSuVk2 UTR nt sequence in this stu- finisher pigs. The rate of single infections of TTSuVk2 was dy, higher similarity (97.1%) was obtained to both the- significantly (p<0.05) higher in finisher pigs relative to su strains from Argentina (TTV2_ARG08) and China (SH/Chi ckling piglets and breeders. A significantly (p<0.05) higher na/2010/PTTV2/129). The similarities to the other Bra breeders.frequency of mixed infections due to TTSuV1 and TTSuVk2 zilianPhylogenetic TTSuVk2 ntanalyses sequences based varied on two between distinct 93.2% models and was found in finisher pigs relative to suckling piglets and- 94.9%. - tive samples within each stage were compared, no signi- When the proportions of TTSuV1- and TTSuVk2-posi topology(kimura two-parameterof the trees generated and tamura-nei) and the bootstrapof the same values me presentedthod (maximum minimal likelihood) and not relevant did not presentdifferences differences among the on ficant (p>0.05) differences were found for weaned piglets or breeders. However, the detection of TTSuV1 in suckling piglets was significantly (p<0.05) more frequent than the two phylogenetic trees. Of all the Brazilian TTSuV1 strains detection of TTSuVk2 or mixed infections of both genera. available, including that in this study, only one (TTSuV1_ When the results of finisher pigs were evaluated, TTSuVk2- BRA15/11) clustered together to the prototypes (Sd-TTV31 detection was significantly (p<0.05) more frequent than- Brazilianand Sd-TTV1p) strains in were the distributedphylogenetic in treedifferent (Fig.1), branches. while the the detection of TTSuV1 or mixed infections by both gene others clustered in two distinct branches. For TTSuVk2, all ra. Mixed infections by TTSuV1 and TTSuVk2 were detec Pesq. Vet. Bras. 33(7):840-846, julho 2013 Torque teno sus virus (TTSuV) infection at different stages of pig production cycle
843 Table 2. TTSuV1 and TTSuVk2 single and mixed-infections in pig fecal samples according to farm type Farms Pig herds TTSuV detection TOTAL (number of sam- ples evaluated) TTSuV1 TTSuVk2 TTSuV1 + (%) Farrow-to-weaning (breeder sows FW I (n TTSuVk2 n n=6 FW III (n=19) 6 2 3 11 (57.9) and boars, suckling piglets, and we- FWFW IVII ((n=24) 6 1 3 10 (41.7) aned pigs until 8 weeks of age) FW V (n =22) 6 4 1 11 (50) FW VI (n=16) 1 8 1 10 (62.5) =18) 2 3 4 9 (50) Subtotal n =20) 7 2 2 11 (55) a
=119n 28 (23.5%) 20 (16.8%) 14 (11.8%) 62 (52.1) n=9 GF II (n Grower-to-finish GFGF III I ( (n=7) - 4 3 7 (100) (9 to 24 weeks of age) GF IV (n=7) - 3 3 6 (85.7) GF V (n =9) 1 5 1 7 (77.8) GF VI (n =5) 1 2 2 5 (100) GF VII (n=6) 1 1 2 4 (66.7) GF VIII (=10)n - 7 3 10 (100) n =6) - 3 2 5 (83.3) =4) 1 1 2 4 (100) Subtotal GF IXn ( =17) - 13 3 16 (94.1)b
=71 4 (5.6%) 39 (54.9%) 21 (29.6%) 64 (90.1) TOTAL (n=190) 32 59 35 126 (66.3) Different letters indicate statistically significant differencesof pig (p<0.05). production in Brazil. These results indicate that TT- SuV infection has spread to pigs of all production stages. - tion than animals from the other stages, in agreement with previousFinisher pigsstudies had thatsignificantly have reported higher ratesthat TTSuV of TTSuV infection detec increases with the age of the animals (Sibila et al. 2009b,
In our study, the overall percentage of TTSuV-positive Aramouni et al. 2010). - formed with rectal swabs (Sibila et al. 2009b), which repor- pigs (66.3%) was higher than that described in a study per studies reported higher rates for TTSuV in fecal samples, suggestingted a low percentage that the fecal-oral (<20%) ofroute TTSuV is andetection. important Previous route of TTSuV transmission (Brassard et al. 2008, Leme et al.
An inversion in the frequencies of infection with the two TTSuV2012). genera relative to the age of pigs within the produc- - - tion cycle was observed during this study. TTSuV1 detec - pigs,tion waswhereas higher the (p<0.05) detection in rates suckling of single piglets infections and progres of TT- Fig.1. Maximum likelihood phylogenetic tree construction using the sively less frequent with the increasing age up to finisher tamura-nei model based on partial (261 nt: 53-314 bp) untrans lated region. Bootstrap values (1,000 replicates) higher than 65% are shown. GenBank accession number of prototypes (Sd-TTV31, SuVk2 and mixed infections increased proportionally with Sd-TTV1p, Sd-TTV2p), Brazilian (TTSuV1_BRA11/07, TTSuV1_ the age of the animals; with finisher pigs presenting higher- BRA12/11, TTSuV1_BRA13/11, TTSuV1_BRA14/11, TTSuV1_ (p<0.05) rates of TTSuVk2 infection than the animals of the BRA15/11, TTSuV2_BRA21/11, TTSuV2_BRA22/11, TTSuV2_- other stages. These findings are corroborated by the re BRA23/11, TTSuV2_BRA24/11, and TTSuV2_BRA25/11), other Asults similar at the result farm waslevel; obtained 5 of the 9in grower-to-finish a longitudinal study farms per did- preference sequences (PTTV1a-VA, PTTV1b-VA, PTTV2b-VA, PT- not present positive results for single infections of TTSuV1. queTV2c-VA), teno felis and virus this wasstudy used TTSuV as out strains group. (• TTSuV1_BRA16/09, presence of TTSuV in different biological samples (Sibila et TTSuV2_BRA26/10) are indicated between parentheses. Tor formed with 1 to 15 week-old animals, which evaluated the DISCUSSION more frequently than TTSuV2 from the nasal swabs of ani- - al. 2009b). Specifically, in that study TTSuV1 was detected- vestigated the rates of TTSuV detection at different stages As far as the authors are aware, this is first study that in mals up to 7 weeks of age, but the rate of TTSuV2 detec tion was higher (p<0.05) than the rate of TTSuV1 in pigs Pesq. Vet. Bras. 33(7):840-846, julho 2013 844
Raquel de A. Leme, Alice F. Alfieri and Amauri A. Alfieri se to TTSuV infection later. The occurrence of immunolo- the rectal swabs demonstrated that the percentage of TT- gical tolerance to the virus due to the infection before the that were at 11 and 15 weeks of age. Moreover, analysis of immunocompetence age may be responsible for persistent TTSuV infection throughout the pig productive life (Ara- pigsSuV2-positive was fairly pigsconstant increased throughout progressively the study from (Sibila 7 weeks et al. 2009b).of age onwards, Although whereas the data the from detection both studies of TTSuV1-positive show similar TTSuV2-induced infections have been demonstrated to trends, there is no clear explanation for the inversion in the bemouni more et al.frequent 2010). in porcine circovirus associated disea- rates of infection by TTSuV species. - A study performed within Czech pig population de- monstrated the increasing frequency of TTSuV infection se (PCVAD)-affected pigs than in non-affected pigs (Keka with ageing, although has revealed no differences between rainen et al. 2006, Blomström et al. 2010, Aramouni et al. 2011), although no association between TTSuV species infection and PCVAD has been identified (Lee et al. 2010). ofthe TTSuV TTSuV1 infection and 2 detection in pigs of rates different for piglets, ages also weaned has beenpigs, In Brazil, Ritterbusch et al. (2012) found TTSuV2 infection evaluatedand adult animalsin the United (Jarosova States et al.and 2011). it was The demonstrated prevalence adultmore pigs,frequently primarily than in TTSuV1 the context infection of co-infection in the reproductive with por- cineorgans, circovirus semen, 2ovarian (PCV2). follicular fluid and lymph nodes of - that both TTSuV1 and TTSuV2 infections increased with ples were positive for both genera of TTSuV. A study per- the age of the animals, with the prevalence of TTSuV1 DNA- formedIn the by present our group study, evaluated 18.4% (35/190) paired organs of the and fecal serum sam diagnosticbeing higher technique (p<0.05) was than used that in of the TTSuV2 American in each study, of the samples from clinically healthy slaughter-age pigs for TT- differentage groups geographical analyzed (Xiao regions et al.used 2012). in these Although studies a might sero SuV infection, where it was demonstrated co-infection due explain the divergence in the results obtained, suggesting that the behavior of the virus may vary between distinct geographical locations. to both TTSuV genera in 87.9% (102/116) of the samples,- It has been demonstrated that a single pig can be infec- whereas single infections of TTSuV1 and TTSuVk2 were ratefound of in TTSuV-induced only 2 and 9 of mixed the 116 infections samples betweenanalyzed, our respec two - studiestively (Leme may be et due al. 2013).to the type The of difference samples inevaluated the detection (fecal bablyted with because more thanmolecular one strain variation of the in TTSuV the TTSuV genera genomic (Huang vs. serum vs. organs). Based on the results obtained from sequenceset al. 2010, couldGallei leadet al. to 2010, antigenic Leme differenceset al. 2013). as This a mecha is pro- the fecal samples, it can be suggested that mixed infections nism to avoid the host immune response. due to TTSuV genera may interfere with viral shedding, leading to lower rates of detection in feces. In the study been shown to be associated with a decrease in the viral An increasing level of anti-TTSuV2-ORF1 antibodies has not possible to determine whether action of the two gene- rabased of TTSuV on the is systemic competitive infection or synergetic. (Leme et al.Thus, 2013) it is it clear was DNA load within the serum (Huang et al. 2011). Although- that TTSuV genera co-infection is not an unusual event, but the result refers to TTSuVk2, and considering the previous- understanding the implications of this result has not been results that TTSuV1 species more frequently infects su ckling piglets from Brazil (Leme et al. 2012), the progres one of the genus limits or favors infection by the other or atsive least production partially ofresponsible anti-TTSuV1 for antibodies decreases in virusresponse excre to- elucidated since it is not known whether the presence of tionearly via exposure feces and is likely. in the Such frequency antibody of production positive results might forbe In this study, the frequency of TTSuV infection for bre- this species of the virus in older animals, since piglets are affects the level of fecal viral shedding (Leme et al. 2012). - - immunological response could not lead to the clearance of tioneders of was TTSuV not insignificantly sows in a study different performed for that in of Spain suckling (Sibila pi typically exposed to TTSuV1 earlier in life. However, the glets (p>0.05). The results are in agreement with the detec results of a study in Czech Republic, which detected TT- co-infectionTTSuV1 infection, rates. and the increasing incidence of infection SuVet al. infection 2009a). However,in higher ourfrequencies results differ in gilts from and the sows reported than by TTSuVk2Age has been with suggested ageing might to be also an explainimportant the factor increase affec in- been found to have higher prevalences of viremia and anti- alsoin piglets, differ withfrom no the significant results obtained differences from according wild boar to serum each ting the profile of TTSuV2 infection because older pigs have- samples,TTSuV genus which (Jarosova showed et that al. 2011).TTSuV2 The infection results presentedwas more nity as the animals become exposed and matures, sugges- bodies (Huang et al. 2011). The slow development of immu Two studies evaluated the TTSuV infection in female breederscommon (p<0.05)and in both than the TTSuV1 frequencies (Martínez of detection et al. 2006). were hi- ted by Xiao et al. (2012), and the progressive increase in the gher in young parity relative to old parity sows (Sibila et frequency of TTSuVk2 infection with age could explain the high frequency of TTSuVk2-positive animals of this study. evaluation could not be done, since we have no information of CzechJarosova Republic. et al. (2011)The lower reported rates of higher TTSuV frequencies detection in of aboutal. 2009a, the ageJarosova of the etfemale al. 2011). breeders In the analyzed. present Anyway, study such pa- serumboth TTSuV1 samples and from TTSuV2 newborn viremia piglets in weaned in that andstudy adult suggest pigs rity number has not been associated with TTSuV infection that young animals developed their immunological respon- in sows (Sibila et al. 2009a).
Pesq. Vet. Bras. 33(7):840-846, julho 2013 Torque teno sus virus (TTSuV) infection at different stages of pig production cycle 845
The breeders included in this study had a higher rate - pectively,Infections in Brazil. due to TTSuV1 and TTSuVk2 were found infections,of TTSuV1 thisdetection. result Althoughreinforces this the ratehypothesis was not that different bree- moreThe frequently observation in sucklingof inversion piglets of TTSuV and finisher genera pigs,infection res ders(p>0.05) may be from a source the detection of TTSuV ratesinfection of TTSuVk2 for piglets. or Studies mixed with the age of infected pigs, and the variation in the num- ber of TTSuV genera-induced mixed infections detected mi- infection and suggested that sow-to-piglet transmission ght be related to the different biological samples used, and reported piglets at first week of age as positive for TTSuV highlights the biological properties of this virus. is mostThere likely are fewto occur Brazilian (Sibila TTSuV et al. nt 2009a, sequences Jarosova available et al. Brazilian pig herds. for2011). phylogenetic studies. The UTR nt sequences similari- StudiesDistinct basedstrains onof TTSuV1the immune and TTSuVk2 response are to presentTTSuV in ties of the TTSuV strains in this study and other Brazilian hosts may help to elucidate the dynamics of TTSuV genera strains revealed discrete genetic variability within each TT- infection and the pathogenicity of these viruses. higher similarities with foreign TTSuV strains (Argentina, Acknowledgments.- - - SuV genus. However, both the TTSuV amplicons presented We would like to thank the following Brazilian Ins viral spread. andtitutes Evaluation for financial of Graduate support: Education the National (CAPES), Counsel Financing of Scientific of Studies and Tech and China, and Norway), indicating the absence of barriers for- nological Development (CNPq), the Brazilian Federal Agency for Support blished based on the complete genome sequences of the Projects (FINEP), and the Araucária Foundation (FAP/PR). Alfieri A.A. and Recently, a new classification for this virus was esta Alfieri, A.F. are recipients of CNPq fellowships. The UTR is the most conserved region among anelloviruses REFERENCES and,known even prototypes belonging (Sd-TTV31, to different Sd-TTV1p, virus species and in Sd-TTV2p). the same A A.A., Parazzi M.E., T E., Médici A A.F. 2006. Fre- quency of group A rotavirus in diarrhoeic calves in Brazilian cattle lfieri akiuchi K.C. & lfieri similar and they both grouped at same branch of the phylo- Age-related tis- geneticgenus, the tree TTSuV1 presented UTR herein.nt sequences Two of of the the Brazilian prototypes nt arese- herds, 1998-2002. Trop. Anim. Health Prod. 38:521-526.
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