Association between average daily gain,faecal dry matter content and concentration of Lawsonia intracellularis in faeces

Background

The objective of this study was to investigate the association between average daily gain and the number of Lawsonia intracellularis bacteria in faeces of growing pigs with different levels of diarrhoea.

Methods

A longitudinal field study (n = 150 pigs) was performed in a Danish herd from day 29 to 47 post weaning. Every third day all pigs were weighed, subjected to a clinical examination and faecal samples were obtained. Faecal samples were subjected to dry matter determination and absolute quantification by PCR for L. intracellularis and porcine circovirus type 2 (PCV2). Association between average daily gain, faecal dry matter content, numbers of L. intracellularis bacteria and PCV2 genome copies in faeces was investigated in a multilevel mixed-effects linear model.

Results

Increasing numbers of L. intracellularis log₁₀ bacteria/g faeces were significantly associated with decreasing average daily gain (P < 0.001). The association was decreasing with increasing faecal dry matter content (P < 0.01). The number of PCV2 log₁₀ copies/g faeces was not significantly associated with average daily gain of the pigs (P > 0.5).

Conclusion

The results suggest a potential application of a PCR quantifying L. intracellularis in growing pigs. Faecal dry matter content must be taken into consideration in interpretation of such test results.     

坏死梭杆菌FN(A)p2001株小鼠感染模型的建立

将鹿源坏死梭杆菌FN(A)p2001分离株以3×108、3×107、3×106、3×105、3×104、3×103个/只等不同菌量,分别接种于6组小鼠,每组10只,逐日观察小鼠感染情况.结果表明,3×106、3×107、3×108个/只菌量感染组小鼠,在接种后3 d～8 d先后死亡,5 d后死亡小鼠的病理变化明显,并从死亡小鼠内脏及脓汁中均检到长丝状及小杆状等多形态典型的坏死梭杆菌;3×104个/只和3×105个/只菌量感染仅表现体重减轻,3×103个/只菌量感染无明显临床表现.由此表明,坏死梭杆菌FN(A)P2001分离株具有很强的感染毒力;对小鼠的最小致死量为106个/只菌量;腹腔接种是适宜的感染途径.从而建立了坏死梭杆菌分离株小鼠感染模型.     

Faecal shedding and serological cross‐sectional study of Lawsonia intracellularis in horses in the state of Minas Gerais,Brazil

Reason for performing the study: Proliferative enteropathy, caused by the intracellular bacterium Lawsonia intracellularis, has been described in horses in Australia, the USA, Canada and European countries but has not been reported in Latin America. The prevalence of the disease in horses worldwide is unknown. Objective: To evaluate the presence of subclinical L. intracellularis infection in horses in the state of Minas Gerais, Brazil. Methods: A longitudinal study using serology and PCR for detecting antibodies (IgG) and shedding of L. intracellularis in faecal samples, respectively, was conducted using a total of 223 horses from 14 different horse farms in Minas Gerais, and from the Veterinary School of UFMG equine herds in Minas Gerais. The immunoperoxidase technique in glass slides was used as the serological test. Results: Twenty‐one horse sera had immunoglobulin G titres of 1:60 and were considered positive. The PCR technique in faeces for L. intracellularis DNA identified 7 horses as faecal shedders. Horses shedding the organism appeared healthy, indicating that subclinical infection of L. intracellularis occurred in the horses. Conclusion: Seropositivity and detection of faecal shedding of L. intracellularis indicates the presence of the agent in the equine population in Minas Gerais. Potential relevance: Results of this study should alert clinicians in countries where proliferative enteropthy in horses has not been reported to consider this disease as a possible cause of enteric disease.     

鹿源坏死梭杆菌毒力菌株FN（AB）94实验动物感染模型的建立

将坏死梭杆菌FN（AB）94分离株以10^6,10^7,10^8,10^9 个/mL等不同菌量，于耳后根颈部皮下分别接种于4组的健康实验家兔，每组3只，逐日观察感染家兔的发病情况，结果，10^8,10^9个／mL，菌量感染组家兔，在接种后9－68 d内先后死亡，68d死亡家兔的病理变化明显，并从死亡家兔内脏及脓法叶，应用触片及分离培养均检到长丝状及小杆状等形态典型的坏死梭杆菌，10^7个/mL感染家兔仅表现体重减轻，10^6个／mL感染家兔无明显临床表现，由此表明，坏死梭杆菌FN（AB）94分离株具有很强的感染毒力，对家兔的最小致死量为10^8个／mL，耳后板颈部皮下接种是适宜的感染途径，从而建立了坏死梭杆菌分离株实验动物感染模型。     

Lawsonia intracellularis proliferative enteropathy in a weanling foal,with a tentative histological diagnosis of lymphocytic plasmacytic enteritis

This Case Report describes a weanling filly with protein-losing enteropathy associated with Lawsonia intracellularis infection. This was diagnosed on the basis of a significant antibody response and a positive faecal PCR result. The histopathological lesion observed in proliferative enteropathy is mucosal hyperplasia, commonly affecting the ileum and colon in foals. Duodenal biopsies obtained from this filly revealed a lymphocytic plasmacytic infiltrate. The filly recovered completely following treatment with erythromycin and no additional medication was administered to treat the lymphocytic plasmacytic infiltrate. This Case Report suggests that lymphocytic plasmacytic infiltrates observed on duodenal biopsies may represent a nonspecific intestinal immune response.     

Comparison of a commercial ELISA with an indirect fluorescent antibody test to detect antibodies to Lawsonia intracellularis in experimentally challenged pigs

Objective The ability of a new commercial ELISA to detect pigs with subclinical proliferative enteropathy (PE) was compared with the traditional indirect fluorescent antibody test (IFAT). Methods Serum samples were selected from pigs with known Lawsonia intracellularis infection status and clinical signs of PE, but the sample population consisted predominantly of pigs subclinically affected by PE. Results Significant association and agreement were shown between the ELISA and IFAT assays. ELISA results correlated well with the duration of L. intracellularis shedding as detected by polymerase chain reaction. Conclusion ELISA can be successfully used to monitor L. intracellularis infection in pigs.     

坏死梭杆菌QL03株绵羊感染模型的建立及免疫保护性试验

坏死梭杆菌是奶牛腐蹄病的重要致病菌。用奶牛源坏死梭杆菌QL03分离株以不同浓度菌量感染绵羊蹄部,通过观察绵羊蹄部感染情况、病理变化和动物回归试验,建立了坏死梭杆菌分离株绵羊感染模型。并通过绵羊免疫保护性试验验证了绵羊作为奶牛源坏死梭杆菌QL03分离株动物模型的可行性,为进一步研究坏死梭杆菌有效的疫苗奠定实验基础。     

Indirect ELISA for the detection of antibodies against Opisthorchis felineus (Rivolta, 1884) and Metorchis bilis (Braun, 1790) in foxes

Serological investigations focused on the detection of specific opisthorchiid liver fluke antibodies in silver foxes (Vulpes vulpes fulva). Animals were experimentally infected with Opisthorchis felineus (nos. 1 and 2) and Metorchis bilis (nos. 3–8) by feeding fish with a counted number of metacercariae. Four foxes remained as non-infected negative controls (nos. 9–12). For the indirect ELISA, an excretory–secretory antigen was produced by in vitro cultivation of O. felineus and M. bilis adults isolated from livers of experimentally infected hamsters.

Immunoglobulin G (IgG) seroconversion against homologous antigen took place between weeks 2 and 6 postinfection (p.i.) and foxes remained seropositive up to the end of the trial at week 41 p.i. In contrast, IgG titres against heterologous antigen remained significantly lower and stayed near the cut-off. All infected animals excreted opisthorchiid eggs, starting between weeks 2 and 4 p.i. The number of liver flukes found at necropsy was relatively low, except in one fox that was sacrificed at the week 11 p.i. These results suggest that the ELISA is a suitable tool for the detection of specific O. felineus and M. bilis antibodies in the fox.     

Goats are susceptible to Bubaline alphaherpesvirus 1 infection: Results of an experimental study

Herpesvirus infections are generally subjected to strong host species restriction, although virological and serological investigations have revealed the possibility of cross-species infections in closely related animal species. In this study we evaluated susceptibility of goats to infection by Bubaline alphaherpesvirus 1 (BuHV-1). Four goats were inoculated intra-nasally with BuHV-1 and monitored clinically, virologically and serologically for 42 days. None of the goats displayed clinical signs although all the animals variably shed the virus by the nasal route during the first 12 days after infection. BuHV-1 was also detected in the white blood cells of two animals in the first week post infection. The results suggest that goats are susceptible to BuHV-1 infection and that they could play an epidemiological role in the circulation/transmission of the virus among domestic and wild ruminants and impact to some extent on the control plans for herpesviruses in cattle.     

猪链球菌2型四川分离株猪体回归试验

选用35~38日龄的健康断奶仔猪21头,分3组,用2005四川分离株SSsc0501分别经静脉、肌肉注射和口服3种途径感染,进行猪体回归试验。肌肉注射组(含菌0.6×108个/mL)16 h开始出现症状,至36 h全部死亡,发病率、病死率均为100%;静脉注射组(含菌0.2×108个/mL)25 h开始出现症状,48 h内全部死亡,发病率和病死率均为100%;口服攻毒组(含菌2×108个/mL)90 h后开始有发病症状,第9天有1头死亡,发病率75%,病死率33%。从感染病死猪的肝脏、脾脏、肾脏、心血、大脑、脑脊液、淋巴结、肺脏和关节液中均分离到链球菌,经鉴定为试验攻毒的目的菌,表明猪体能够很好地用于猪链球菌2型动物感染模型,同时说明该菌侵害器官广泛,为进一步探讨该病的综合防制提供了重要技术依据。     

Effect of an Immunosuppressor (Dexamethasone) on <Emphasis Type="Italic">Eperythrozoon</Emphasis> Infection

The aim was to study the relationship between the infection rate of Eperythrozoon suis and the status of the immune system. Four pigs with chronic eperythrozoonosis were divided into experimental and control groups. Immunosuppression of the experimental group was accomplished by injecting with high-dose glucocorticoid (dexamethasone) on 3 consecutive days. Microscopic examination of blood smears was performed to observe the change of infection rate after administration. The blood samples of each group were collected on day 7 after administration for half-nested PCR assay. The microscopic results showed that the infection rate of the experimental group rose distinctly by 40 h late and remained at 90% in the days following administration. No changes were observed in the control group. PCR results showed a single expected 250 bp fragment in each group, which validated the positive microscopic results. This study demonstrated the significant effect of dexamethasone (DEX) on Eperythrozoon infection.     

Experimental Infection with Mycobacterium Avium,Serotype 2, in Pigs: 3. Oral Infection with Small Doses of M. Avium*

Pigs were inoculated orally with Mycobacterium avium in doses ranging from 15.6 × 10² to 15.6 × 10⁶ viable units daily for 15 days (Table 1). The animals were necropsied 31–32 days after the last inoculation.Pigs given doses of 15.6 × 10⁶ and 15.6 × 10⁵ viable units showed delayed hypersensitivity to avian tuberculin 24 days after the last inoculation (Table 2). The pig inoculated with 15.6 × 10⁶ viable units showed macro- and/or microscopic lesions of the intestines and the liver, and of the mandibular, mesenteric and hepatic lymph nodes. Cultures showed growth of M. avium from the same tissues and from the spleen and the left tracheobronchial lymph node. The pig inoculated with 15.6 × 10⁵ viable units showed a pronounced granulomatous infiltration in the tonsils and the mesenteric lymph nodes. Growth of M. avium was obtained from the tonsils, the intestinal mucosa (Peyer patch) and the mandibular and mesenteric lymph nodes. Viable unit counts were high in the tonsils and in the mesenteric lymph nodes (Tables 3 and 4).Lower doses gave rise to a minimal tissue reaction and/or very low viable unit counts, and are not considered to be capable of producing a progressive tuberculosis.     

A Randomized Blinded Crossover Clinical Trial to Determine the Effect of an Oral Joint Supplement on Equine Limb Kinematics,Orthopedic, Physiotherapy,and Handler Evaluation Scores

Despite the range of oral joint supplements available, there has been very limited research into their efficacy. The study aimed to determine the effect of an oral joint supplement on limb kinematics, orthopedic, physiotherapy, and handler evaluation in horses. Supplement S or placebo P was fed to 24 horses for 21 days each in a random order. Horses were evaluated at days 0 (baseline), 21 (after first treatment), and 42 (after second treatment). Assessments included the following: clinical orthopedic evaluation for straight line/lunging circle in walk and trot; high-speed motion capture determined hindlimb kinematics for straight-line trotting; grading of limb range of motion (ROM) and muscle tone based on standardized physiotherapy criteria; handler grading of specific criteria during pasture, groundwork, and ridden exercise. Effect of treatment, sequence, limb, and interactions were investigated using linear-mixed models. S was associated with significantly lower lameness grade in a straight line (P = .001) and circle (P = .010), with individual horses improving up to 2/10 grades over P/baseline. S was associated with significantly improved ROM and muscle tone. Ridden/groundwork scores were significantly higher with S compared to P/baseline. With S, horses were graded significantly higher for “ease of movement” at pasture compared with P/baseline. For horses with hindlimb lameness, S was associated with significantly greater tarsal flexion than baseline (4.2% greater, P < .020) or P (2.7% greater, P < .037). S was associated with less lameness and improved physiotherapy scores, ridden/groundwork scores, and pasture “ease of movement.” Increased midstance tarsal flexion of lame limbs may indicate improved mobility/comfort during peak loading, supporting a positive effect of S.     

猪细环病毒的检测及与多种病原混合感染的调查分析

为了解细环病毒(Torque teno virus,TTV)在广西猪群中的感染情况,本研究运用Nest-PCR方法,对2009—2011年采自广西140个规模猪场的156份血液、流产胎儿及肺脏、脾脏、肾脏、肝脏、淋巴结等组织样品进行检测,并对阳性样品的非编码区(UTR)进行克隆测序及遗传进化分析;同时对部分样品进行猪圆环病毒2型(PCV2)、猪繁殖与呼吸综合征病毒(PRRSV)、典型猪瘟病毒(CSFV)、伪狂犬病病毒(PRV)检测及细菌的分离鉴定。结果发现,广西猪群中TTV总感染率达到93.6%,TTV2的感染率(76.9%)不仅明显高于TTV1(16.7%),且毒株间遗传变异较大。TTV多与PCV2和PRRSV混合感染,且以与PRRSV混合感染率更高(64.29%)。猪群中存在2重、3重,甚至4重TTV与其他病毒的混合感染。临床上TTV与细菌的混合感染(或细菌继发感染)以链球菌和副猪嗜血杆菌多见。本研究证实在广西猪群中存在TTV感染,且存在普遍的TTV与PRRSV、PCV2和CSFV混合感染。     

猪繁殖与呼吸综合征、猪圆环病毒2型、猪伪 狂犬病病毒混合感染的检测分析

本研究采用RT-PCR方法对2010年12月至2011年11月采集于豫西地区的170份疑似PRRSV感染猪病料进行病原检测,得到102份高致病性PRRSV阳性样本,在此基础上应用PCR方法检测PCV2和PRV的感染情况,并计算混合感染率。试验结果显示,豫西地区PRRS发病猪主要疫病的总混合感染率为58.52%,二重混合感染率为39.21%,三重混合感染率为19.61%,其中PRRSV/PCV2型二重混合感染最严重,混合感染率达33.33%;春夏和秋冬总混合感染率分别为48.57%、81.25%,而且不管是二重还是三重混合感染,秋冬均比春夏更严重,尤其是PRRSV/PCV2/PRV型三重混合感染,秋冬与春夏季节的混合感染率相差较大,分别为37.50%、11.43%;PRRS发病猪从哺乳期到育肥期都有混合感染,混合感染率分别为42.10%、50.00%、100.00%,混合感染程度逐渐加重,主要集中在育肥期;不同发病时期的最高混合感染型也有所不同,其中哺乳期最高混合感染型为PRRSV/PCV2,混合感染率为42.10%,保育期最高混合感染型为PRRSV/PCV2、PRRSV/PCV2/PRV,混合感染率均为22.73%,育肥期最高混合感染型为PRRSV/PCV2/PRV,混合感染率为50.00%。本研究反映了豫西地区PRRS发病猪群与猪圆环2型及猪伪狂犬病的混合感染情况和规律,为该地区PRRS及其混合感染的临床诊治和区域性防控工作的进行提供了理论依据和指导。     

Nucleotide Sequencing and Analysis of 16S rDNA and 16S-23S rDNA Internal Spacer Region (ISR) of Taylorella equigenitalis, as an Important Pathogen for Contagious Equine Metritis (CEM)

The primer set for 16S rDNA amplified an amplicon of about 1500 bp in length for three strains of Taylorella equigenitalis (NCTC11184^T, Kentucky188 and EQ59). Sequence differences of the 16S rDNA among the six sequences, including three reference sequences, occurred at only a few nucleotide positions and thus, an extremely high sequence similarity of the 16S rDNA was first demonstrated among the six sequences. In addition, the primer set for 16S-23S rDNA internal spacer region (ISR) amplified two amplicons about 1300 bp and 1200 bp in length for the three strains. The ISRs were estimated to be about 920 bp in length for large ISR-A and about 830 bp for small ISR-B. Sequence alignment of the ISR-A and ISR-B demonstrated about 10 base differences between NCTC11184^T and EQ59 and between Kentucky188 and EQ59. However, only minor sequence differences were demonstrated between the ISR-A and ISR-B from NCTC11184^T and Kentucky188, respectively. A typical order of the intercistronic tRNAs with the 29 nucleotide spacer of 5'-16S rDNA-tRNA^Ile-tRNA^Ala-23S rDNA-3' was demonstrated in the all ISRs. The ISRs may be useful for the discrimination amongst isolates of T. equigenitalis if sequencing is employed.     

Design,optimization, and application of a conventional PCR assay with an internal control for detection of ‘Candidatus Mycoplasma turicensis’ 16S rDNA in domestic cats from Brazil

Background: ‘Candidatus Mycoplasma turicensis’ (CMtc) is a hemotrophic bacterial species that can, alone or in combination, induce anemia in cats. The diagnostic test of choice for hemoplasma infections is PCR. Conventional PCR assays have been developed for the detection of Mycoplasma haemofelis (Mhf) and ‘Candidatus M. haemominutum’ (CMhm) but not for CMtc. Although real‐time PCR assays have been reported for all of the feline hemoplasmas, the expense of necessary instrumentation precludes its use in Brazil and many other countries. Objectives: The goals of this study were to develop and optimize a conventional PCR assay to diagnose CMtc using an internal control to detect false‐negative results, and to evaluate the occurrence of CMtc infection in domestic cats from Brazil. Methods: Species‐specific primers were designed and a PCR assay was developed for the detection of CMtc 16S rDNA in cat blood. Sensitivity was determined by serial 10‐fold dilutions of plasmid and DNA extracted from blood from an experimentally infected cat. EDTA blood samples from 373 cats were collected. DNA was extracted using a silica‐based protocol and tested using the PCR assay. Results: Primer concentration, annealing temperature, and MgCl₂ concentration were optimized in the presence and absence of the internal control. Two samples negative for the internal control were excluded. Of the remaining 371 samples (117 healthy and 254 unhealthy cats), 17 (4.6%) were positive for CMtc. Conclusion: These results demonstrate the utility of an optimized PCR assay to detect CMtc in feline blood samples. We also report for the first time the prevalence of CMtc infection in domestic cats in Brazil.