Preliminary study of Porcine circovirus type 2 and Torque teno sus virus coinfection frequencies in Brazilian pig herds

Torque teno sus virus (TTSuV) is emergent in swine herds. Recent studies have shown an increased frequency of TTSuV2 in Porcine circovirus type 2 (PCV2)-associated diseases (PCVAD), which are endemic in many swine-producing countries, including Brazil. Coinfection with several other viral and bacterial agents results in an increased incidence of more severe PCVAD. Given the limited information on TTSuV and PCV2 coinfection, especially in Brazilian swine herds, this study made a preliminary estimation of the occurrence of coinfection in swine herds by testing samples from different categories. Between 2008 and 2009, 111 samples of feces and 23 serum samples from 5 swine herds were tested for PCV2 and TTSuVs and the results analyzed for associations between these agents. No significant differences in coinfection frequency were observed for PCV2 + TTSuV1 or for PCV2 + TTSuV2 between nursery piglets (P = 0.730), growing pigs (P = 0.331), or sows (P = 0.472). However, a significant difference was observed for PCV2 + TTSuV1 + TTSuV2 between nursery piglets and growing pigs (P = 0.004; Fisher’s exact test). Phylogenetic studies agreed with the grouping of TTSuV1 and TTSuV2 into 2 different clades, with no distinct pattern of clustering of these isolates with the animal categories.     

吉林部分地区TTSuVs与PCV2混合感染情况调查及其与PMWS相关性分析

为了解吉林地区猪细环病毒(TTSuVs)与Ⅱ型猪圆环病毒(PCV2)混合感染情况,分析TTSuVs感染与仔猪多系统衰竭征(PMWS)的相关性.试验通过PCR技术对2019年收集到的吉林部分地区的10家规模化猪场130份血清样本进行检测;并应用本实验已建立的PCV2、TTSuVs实时荧光定量PCR检测方法,对PCV2阳性...     

猪细环病毒和猪圆环病毒2型混合感染状况的调查

为分析我国猪细环病毒(TTSuV)和猪圆环病毒2型(PCV2)的共感染情况,利用所设计的TTSuV(TTSuV1、TTSuV2)和PCV2特异性引物对我国29个省市采集的猪群血清样品同时进行PCV2和TTSuV(TTSuV1、TTSuV2) PCR检测,分析混合感染情况.结果所检测的1898份样品中,TTSuV阳性为1103份(58％),PCV2阳性为435份(23％).阳性样品中呈混合感染的有275份(14％),其中TTSuV1和PCV2为249份(13％),TTSuV2和PCV2为200份(10％),均为阳性的有174份(9％).调查结果显示,我国猪群中TTSuV和PCV2混合感染现象较为普遍,对地区性分布特征和饲养模式等影响因素的分析表明TTSuV和PCV2混合感染情况存在地区性差异(P＜0.01),但饲养模式并不是共感染的关键因素.     

Lack of effect of piglet vaccination against Porcine circovirus type 2 (PCV2) on serum viral loads of Torque teno sus virus 2 (TTSuV2)

Anelloviruses are small, non-enveloped viruses with circular single stranded DNA, which infect a number of animal species as well as humans. In pigs, two distinct Torque teno sus virus (TTSuV) species have been described so far, being one of them linked to disease occurrence. Specifically, TTSuV2 loads in serum have been found increased in pigs suffering from postweaning multisystemic wasting syndrome (PMWS). Since this pathological condition is able to be controlled by means of porcine circovirus type 2 (PCV2) vaccination, it was hypothesized the possibility that such vaccination would have an impact on TTSuV2 prevalence and loads. A total of 150 pigs were divided in two study groups. Half of them received a PCV2 commercial vaccine, while the other half remained as non-vaccinated controls. PCV2 infection was monitored at 3-4, 8, 12, 16 and 21 weeks of age by means of an standard PCR, while TTSuV2 loads were determined at 8, 16 and 21 weeks of age by a quantitative PCR. No obvious PMWS clinical signs were observed among studied animals, although PCV2 infection was confirmed in both groups of pigs. Almost all pigs got TTSuV2 infection throughout the study period, independently of the PCV2 vaccination status of animals. Moreover, TTSuV2 load did not show significant differences between different pig groups at each sampling time, but mean viral load increased with age. Taking into account that previous results suggest that TTSuV2 load in serum is increased in the background of PMWS, the present study suggests that this is not the case in a PCV2 subclinical infection scenario. Therefore, vaccination of PCV2 subclinically infected pigs did not modify the outcome of TTSuV2 infection.     

Torque teno sus virus infection in suckling piglets from Brazilian pig herds

Torque teno sus virus (TTSuV) is responsible for the infection of pig herds around the world. The aim of this study was to analyse the presence of natural infection by both species of TTSuV in suckling piglets from major pig-producing regions of Brazil. Faecal samples (n?=?135) from 1 to 3-week-old suckling piglets from the Southern, Southeast and Midwest regions of Brazil were analysed by PCR assay to detect TTSuV1 and 2. TTSuV1 and 2 DNA was identified in 65 (48.1?%) and 23 (17?%) of piglet faecal samples, respectively. Co-infection by both species of TTSuV was detected in 17 (12.6?%) samples. Detection of TTSuV1 was significantly higher than that of TTSuV2 in the three Brazilian regions together (p?<?0.05). Based on age of animals, TTSuV1 infection was statistically higher than TTSuV2 in each age group (p?<?0.05). For all of the age groups together, no statistical difference was detected in the number of TTSuV1 and 2 positive results (p?>?0.05). These findings revealed that TTSuV infection has disseminated in pig herds from different geographic Brazilian regions, and the presence of TTSuV in suckling piglet faecal samples suggested the early infection by the virus and the potential of these animals in spreading the virus.     

The effects of transplacental porcine circovirus type 2 infection on porcine epidemic diarrhoea virus-induced enteritis in preweaning piglets

The effects of transplacental porcine circovirus type 2 (PCV2) infection on porcine epidemic diarrhoea virus (PEDV)-induced enteritis were examined in neonatal piglets. Six pregnant sows were randomly allocated to an infected (n=3) or control group (n=3). Three pregnant sows were inoculated intranasally with 6 mL of tissue culture fluid containing 1.2 x 10(5) tissue culture infective doses 50% (TCID(50))/mL of PCV2 strain SNUVR000470 three weeks before the expected farrowing date. Three control pregnant sows were similarly exposed to uninfected cell culture supernatants. Thirty piglets from PCV2-infected sows were randomly assigned to two groups (A and B) of 15 piglets each. Another 30 piglets from noninfected sows were randomly assigned to two groups (C and D) of 15 piglets each. The piglets in groups A and C were dosed orally at three days of age with 2mL of virus stock (1 x 10(6.5) TCID(50)/mL) of the PEDV strain, SNUVR971496, at the third passage. The mean villous height and crypt depth (VH:CD) ratio in PEDV-infected piglets from PCV2-infected sows (group A) were significantly different from those of the PEDV-infected piglets from PCV2 negative sows (group C) at 36, 48, and 72 h post-inoculation (hpi) (P<0.05). In PEDV-infected piglets from PCV2-infected sows (group A), significantly more PEDV nucleic acid was detected in the jejunal tissues (P<0.05) at 24 hpi than in the same tissues of the PEDV-infected piglets from PCV2 negative sows (group C). Thereafter, at 36, 48, 60, and 70 hpi significantly more PEDV nucleic acid (P<0.05) was detected in the jejunal tissues of the PEDV-infected piglets from PCV2 negative sows (group C) than those of the PEDV-infected piglets from the PCV2-infected sows (group A). It is concluded that the clinical course of PEDV disease was markedly affected by transplacental infection of PCV2.     

Detection of Torque teno sus virus types 1 and 2 by nested polymerase chain reaction in sera of sows at parturition and of their newborn piglets immediately after birth without suckling colostrum and at 24 hr after suckling colostrum

This study was performed to clarify the sow-to-fetus transmission pathway of Torque teno sus virus (TTSuV) types 1 (TTSuV1) and 2 (TTSuV2). For this purpose, detection of TTSuV1 and TTSuV2 (TTSuVs) in sera of 6 sows (Sows 1-6) at parturition and in sera of their newborn piglets immediately after birth without suckling colostrum was performed by nested polymerase chain reaction (nPCR). These sows were bred using semen that had tested negative for TTSuVs. In a TTSuV1- and TTSuV2-positive sow (Sow 1), TTSuV1 and TTSuV2 were detected in 4 and 5 of 12 newborn littermates, respectively. In a TTSuV1-positive sow (Sow 2), TTSuV1 was detected in 1 of 8 newborn littermates. In 4 TTSuV1- and TTSuV2-negative sows (Sows 3-6), TTSuV1 was detected in 6 out of the 25 newborn piglets of 3 sows (Sows 3-5), while TTSuVs were not detected in all 13 piglets of 1 sow (Sow 6). In addition, to investigate the possibility of a sow-to-piglet transmission pathway of TTSuV via colostrum, TTSuV1 and TTSuV2 in sera of 12 newborn piglets from Sows 1-3 were examined by nPCR. Immediately after birth without suckling colostrum, TTSuV1 and TTSuV2 were not detected in 10 and 8 of 12 newborn piglets, respectively; however, at 24 hr after suckling colostrum, TTSuV1 was detected in 6 piglets, while TTSuV2 was not detected in any piglets. These results confirmed the existence of a sow-to-fetus transmission pathway of TTSuV during normal pregnancy and suggested a possibility of sow-to-piglet transmission of TTSuV via colostrum.     

Reproduction of postweaning multisystemic wasting syndrome in pigs by prenatal porcine circovirus 2 infection and postnatal porcine parvovirus infection or immunostimulation

Postweaning multisystemic wasting syndrome (PMWS) was reproduced in prenatally porcine circovirus 2 (PCV2)-infected pigs by either postnatal infection with porcine parvovirus (PPV) or by immunostimulation. Twenty-four randomly selected piglets from 3 sows, which had been experimentally infected during gestation with PCV2, were randomly divided into 3 groups; group 1 (prenatal PCV2 infection, with postnatal PPV infection), group 2 (prenatal PCV2 infection, with postnatal keyhole limpet hemocyanin, emulsified in incomplete Freund's adjuvant [KLH/ICFA] injection), and group 3 (prenatal PCV2 infection only). Twenty-four randomly selected piglets from 3 uninfected sows were randomly divided into 3 groups; group 4 (no prenatal infection, with postnatal PCV2 and PPV infection), group 5 (no prenatal infection, with postnatal PCV2 infection), and group 6 (negative control pigs). Body weight in negative control pigs (group 6) was increased significantly compared with pigs in groups 1, 2, and 4 at 49, 52, 56, 59, and 63 days of age. The granulomatous inflammatory reaction and lymphoid depletion that are typical lesions in pigs with PMWS were observed in the lymph node of piglets in groups 1, 2, and 4 at 63 days of age. Pigs in group 3 had significantly fewer PCV2-positive cells than those from groups 1, 2, 4, or 5. When the prenatally PCV2-infected pigs were infected with PPV or injected with immunostimulant in the postnatal period, they developed PMWS. Thus, factors that potentiate the progression of prenatal PCV2 infection to PMWS are postnatal infection with PPV or immune stimulation.     

Detection of Torque teno sus virus 1 and 2 in tissues from stillborn piglets delivered by sows via natural farrowing

We detected Torque teno sus virus 1 and 2 (TTSuV1 and TTSuV2) in tissue samples from 18 stillborn piglets using nested polymerase chain reaction. The detection rates of TTSuV1 and TTSuV2 were 78% and 50%, respectively, with 83% of the stillborn piglets positive for TTSuV1 or TTSuV2. TTSuV1 was detected highest in the liver (72%) followed by heart (56%), spleen (38%) and tonsils (38%) while TTSuV2 was detected highest in the tonsils (38%) followed by liver (33%), spleen (25%), and heart (17%). These results indicate that TTSuVs are commonly present but not equally distributed among the tissues of stillborn piglets.     

Temporal distribution of porcine circovirus 2 genogroups recovered from postweaning multisystemic wasting syndrome affected and nonaffected farms in Ireland and Northern Ireland.

Porcine circovirus type 2 (PCV2) is now recognized as the essential infectious component of porcine postweaning multisystemic wasting syndrome (PMWS). PMWS was first recognized in high-status, specific pathogen-free pigs in Canada in 1991 and is now an economically important disease that affects the swine industry around the world. Recently, reports of genomic studies on PCV2 viruses indicated that 2 distinctive genogroups of PCV2 exist.4,10 This report involves the results of a study on the distribution of predominant PCV2 genogroups recovered from samples taken from PMWS-affected and PMWS-nonaffected farms on the island of Ireland over a 9-year period and the results of a study on PCV2 genogroup recovery from fecal samples taken from a farm in Northern Ireland from 2003 to 2005 that was first diagnosed as PMWS positive in August 2005. The results indicate that, although at least 2 distinct genogroups of PCV2 have been circulating on pig farms on the island of Ireland, there does not appear to be a direct relationship between infection with these different genogroups of PCV2 and the development of PMWS.     

Seroprevalence of Torque teno sus virus types 1 and 2 in postweaning multisystemic wasting syndrome-suspected pigs and porcine circovirus type 2-vaccinated normal pigs in southern Japan

We investigated the seroprevalence rate of Torque teno sus virus types 1 (TTSuV1) and 2 (TTSuV2) in the sera of 38 post weaning multisystemic wasting syndrome (PMWS)-suspected pigs and 43 porcine circovirus type 2 (PCV2)-vaccinated normal pigs on 3 commercial pig farms in southern Japan by using nested polymerase chain reaction. High seroprevalence rate of TTSuVs was observed in both PMWS-suspected pigs (100%) and PCV2-vaccinated normal pigs (90.7%). The seroprevalence rate of TTSuV2 was significantly higher in the PMWS-suspected pigs than in PCV2-vaccinated normal pigs (97.4% versus 81.4%, P<0.05), whereas no such difference was observed for TTSuV1 between the 2 groups of pigs. In both pig groups, the seroprevalence rate of TTSuV2 was significantly higher than that of TTSuV1 (P<0.01-0.05). These results show that TTSuVs are highly seroprevalent in both PMWS-suspected pigs and PCV2-vaccinated normal pigs with TTSuV2 being more seroprevalent in the former than in the latter.     

Type I restriction-modification system and its resistance in electroporation efficiency in Flavobacterium columnare

The role of swine torque teno sus viruses (TTSuVs) as co-factors in disease syndromes involving porcine circovirus strain 2 (PCV2) and porcine reproductive and respiratory disease syndrome virus (PRRSV) has been a debatable subject. In this study, the prevalence of TTSuVs in Iowa, the leading pork producing state in the U.S., was estimated by a duplex PCR. The PCR is capable of simultaneously detecting both teno sus viruses 1 and 2 (TTSuV1 and 2). Based on an analysis of 300 random samples representing six major geographical regions of the state, the overall prevalence rates for TTSuV1 and 2 were 47.34% and 24.67% respectively while the combined prevalence rate was 52.33%. The epidemiological association of TTSuV1 and 2 with the common etiological agents of the porcine respiratory disease complex (PRDC) namely porcine PRRSV, PCV2, Mycoplasma hyopneumoniae and swine influenza virus (SIV) was estimated in lung tissue derived from 45 pigs showing clinical signs of PRDC. Notably, 86.67% of the PRDC-suspect samples were positive for TTSuV1 in comparison to the baseline population prevalence rate of 47.34%. However, the prevalence of TTSuV2 (26.67%) was not significantly different. TTSuV1 was detected in 80.00%, 81.81%, 75.00% and 77.78% of the PRRSV, SIV, M. hyopneumoniae and PCV2 positive PRDC-suspect samples respectively. Our results indicate that TTSuV1 is strongly associated with clinical PRDC and support the hypothesis that TTSuVs might function as co-factors in PRDC. Further studies to define their possible role in the pathogenesis of swine respiratory diseases are warranted.     

A proposal on porcine circovirus type 2 (PCV2) genotype definition and their relation with postweaning multisystemic wasting syndrome (PMWS) occurrence

Porcine circovirus type 2 (PCV2) is the essential infectious agent of postweaning multisystemic wasting syndrome (PMWS). Despite first sequencing studies did not find any association between PCV2 sequences and PMWS occurrence, recent works have suggested the opposite. In the present study, 87 open reading frame 2 (ORF2) sequences obtained from pigs with different clinical conditions and coming from farms with different PMWS status were analyzed. Results further confirmed the existence of two genogroups and the definition of two PCV2 genotypes (1 and 2) is proposed. All sequences included in genotype 1 came from pigs from PMWS affected farms, while all sequences obtained from non-PMWS affected farms corresponded to genotype 2. Moreover, infection of single pigs from PMWS affected farms harbouring both genotypes is described. Present results suggest that PCV2 genotype 1 may potentially be more pathogenic than PCV2 genotype 2.     

猪圆环病毒2型感染对猪瘟弱毒疫苗接种猪免疫应答的影响

为探索猪圆环病毒2型(PCV2)感染对猪瘟(CSF)弱毒疫苗接种猪免疫应答的影响,将20头28 d断奶仔猪随机分为V-I、I-V、V和C4组,5头·组-1.V-I组在接种CSF弱毒疫苗后2d感染PCV2;I-V组在感染PCV2 后2d接种CSF弱毒疫苗;V组只接种CSF弱毒疫苗;C组为空白对照组.共免疫2次,间隔21 d.免疫后定期检测血清CSFV特异性抗体水平、外周血淋巴细胞(PBLC)增殖活性和PBLC中IFN-γ、IL-2、IL-4和IL-10 mRNA的表达水平.结果显示:在CSF弱毒疫苗免疫前或免疫后感染PCV2,均会导致CSFV抗体水平低下,血清抗体阳转率下降,PBLC增殖活性降低.初次免疫后,V-I与I-V组的PBLC内IFN-γ、IL-2、IL-4和IL-10 mRNA的表达量严重不足,其中V-I组的表达量最低.加强免疫后V-I与I-V组的PBLC内IFN-γ与IL-10的表达失衡,IL-2和IL-4的表达缺乏,其中I-V组的细胞因子表达失衡和缺乏更严重.上述研究表明,CSF弱毒疫苗免疫前或免疫后感染PCV2均会影响机体的体液和细胞免疫应答水平,导致PBLC内细胞因子的表达严重抑制和紊乱.     

High prevalence of porcine circovirus viremia in newborn piglets in five clinically normal swine breeding herds in North America

Porcine circovirus type 2 (PCV2) can be vertically transmitted resulting in fetal infection with or without clinical signs and lesions. The primary objective of this study was to assess the prevalence of intrauterine PCV2 infection in clinically normal newborn piglets in conventional pork production facilities. Five commercial breeding herds located in the U.S. and Mexico were included in the study. A total of 125 sows and 3-5 neonatal piglets per sow were arbitrarily selected. Blood and colostrum samples were collected from sows. Blood was collected from piglets prior to suckling. All samples were analyzed for the presence of anti-PCV2 IgG antibodies and presence and amount of PCV2 DNA. In addition, PCV2 DNA positive samples were further subtyped into PCV2a and PCV2b. All (125/125) sow colostrum samples and 96.8% (121/125) of the sow serum samples and 21.4% (107/499) of the piglet pre-suckle serum samples were positive for anti-PCV2 IgG antibody. The overall PCV2 DNA prevalence was 47.2% (59/125) in sow serum, 40.8% (51/125) in sow colostrum, and 39.9% (199/499) in pre-suckle piglet serum. In the PCV2 DNA positive samples, PCV2b was detected at a higher frequency (69.5% for sow serum, 84.3% for sow colostrum, and 74.4% for piglet serum) compared to PCV2a (18.6% for sow serum, 9.8% for sow colostrum, and 15.6% for piglet serum). Concurrent PCV2a and PCV2b infection was detected in 11.9% of the sow serum, in 5.9% of the colostrum samples, and in 10.0% of the piglet serum samples. In conclusion, an unexpectedly high prevalence of PCV2 viremia was detected in healthy sows (serum and colostrum) and their pre-suckle piglets in the five breeding herds investigated and PCV2b was more prevalent than PCV2a. This information adds to the knowledge of PCV2 infection in breeding herds.     

Reproduction of postweaning multisystemic wasting syndrome (PMWS) in immunostimulated and non-immunostimulated 3-week-old piglets experimentally infected with porcine circovirus type 2 (PCV2)

Postweaning multisystemic wasting syndrome (PMWS) in swine is causally associated with the newly recognised pathogen, porcine circovirus type 2 (PCV2). In this study, 3-week-old SPF PCV2-seronegative piglets were inoculated intranasally with PCV2. The effect of immunostimulation on the induction of PMWS was investigated by immunisation with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freunds adjuvant. The study was terminated 5 weeks after inoculation. While disease was not observed in the age-matched controls, two out of five non-immunised PCV2-infected piglets died on postinoculation day (PID) 21, and one was euthanized on PID 25 in moribund condition. These animals had appeared lethargic with persistent fever from PID 12 onwards. The euthanized pig appeared smaller than littermates and suffered from jaundice. At postmortem examination, gastric ulceration, icterus, and liver and thymus atrophy were observed. Furthermore, histological lesions of degenerating hepatocytes and hepatitis in combination with lymphoid depletion and syncytial cells in lymph nodes were consistent with the diagnosis of PMWS. One out of five immunostimulated PCV2-infected piglets was euthanized on PID 22 with convulsions after a period with wasting. This pig was lethargic from PID 14 onwards with persistent fever from PID 8 and transient dyspnoea. No differences in clinical signs, gross pathologic or histological findings were observed for the remaining non-immunostimulated and immunostimulated PCV2-infected piglets. All 10 PCV2-inoculated piglets seroconverted to PCV2 within 14 days after inoculation. By virus isolation, quantitative polymerase chain reaction (Q-PCR), and immunostaining of cryostat sections, it was demonstrated that lymphoid tissue contained abundant PCV2 antigen. Viral DNA load in serum samples was assessed by Q-PCR. All four PMWS-affected piglets had high levels of PCV2 DNA in serum, suggesting that there was a correlation between high levels of viral DNA in serum and the development of PMWS. In conclusion, infection with PCV2 caused PMWS in SPF piglets, however, the immunostimulation did not seem to play a critical role.     

Pathogenicity of experimental infection with 'pneumotropic' porcine coronavirus

Virus localisation and lesions were studied in 14-one-week-old piglets following combined intranasal-oral inoculation with a British isolate of 'pneumotropic' porcine coronavirus (PCV) and were compared with the effects of transmissible gastroenteritis virus (TGEV) infection in five piglets. Unlike TGEV-infected piglets, all PCV-inoculated piglets remained clinically healthy. Seroconversion was detected at seven days after inoculation. Mild bronchointerstitial pneumonia involving terminal airways was consistently present at two days after infection and thereafter. Both PCV and TGEV infected bronchiolar epithelium and alveolar macrophages but, unlike TGEV, replication by PCV in villous enterocytes was limited and did not cause villous atrophy.     

PCV2感染对仔猪NO-NOS系统的动态影响

将19头PCV2和PRRSV血清抗体阴性的普通断奶仔猪分为对照组(4头)和攻毒组(15头),攻毒组每头仔猪滴鼻接种PCV2病毒悬液4mL(5×105 TCID50/mL)并用KLH刺激,分别在攻毒后14、21、35d各扑杀5头仔猪采集血清和脾脏、淋巴结、胸腺(对照组4头在攻毒当天扑杀)。检测各种组织中NO、TNOS和iNOS的含量。结果显示,攻毒猪各组织中NO含量均在攻毒后14d显著升高(P<0.05),然后缓慢下降;血清和3种免疫器官中NOS(包括TNOS和iNOS)活性的变化趋势比较一致,均表现出先升高然后再逐渐降低的特点。此外,iNOS活性变化与其相应的组织中NO含量呈显著正相关(P<0.01)。结果表明,PCV2在感染早期(1～14d)可激活仔猪多种组织中NO-NOS系统,中后期逐渐恢复,这种变化与PCV2所致的组织损伤密切相关,因此,NO-NOS系统可能是PCV2相关疾病发生发展的重要信号。     

上海地区出现猪繁殖与呼吸综合征和2型猪圆环病毒混合感染

上海地区6个规模化猪场断奶后仔猪出现全身消耗性综合征，剖检的18头病仔猪都表现肺脏严重病变和淋巴结肿大出血。分别设计针对猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus，PRRSV)N蛋白和2型猪圆环病毒(porcine circovirus type2，PCV-2)部分基因的特异性PCR引物，通过RT—PCR和PCR技术从患病猪肺脏组织均扩增出PRRSV和PCV-2的特异基因片段。结合临床症状和流行病学调查，证实上海地区出现PRRSV和PCV-2的混合感染。     

Development of Loop-mediated Isothermal Amplification Assay for Detection of Torque teno sus Virus Type 2

In order to develop a loop-mediated isothermal amplification (LAMP) assay for rapid and specific detection of Torque teno sus virus type 2 (TTSuV2), two pairs of primers were designed according to the untranslated regions and the part of open reading frame 1 of TTSuV2.The LAMP system was optimized by adjusting the concentrations of some components and reaction conditions.The optimized amplification conditions of LAMP assay was at 64 ℃ for 90 min.The results showed the LAMP assay was specific for TTSuV2 detection, which could achieve a detection limit of 100 copies/μL viral nucleic acid, and no cross-reaction with TTSuV1, PCV2, CSFV, PRRSV and PBoV.In conclusion, this assay was a rapid, specific and sensitive detection technique which could provide a assistance for the rapid detection of TTSuV2.