产气荚膜梭菌ε毒素突变体的表达及免疫保护力评价

为获得产气荚膜梭菌ε毒素(ETX)的重组突变体,并评价其毒力及免疫原性。对已知的D型产气荚膜梭菌ETX编码基因进行优化设计,并将第106位组氨酸突变为脯氨酸,经人工合成获得基因片段GETXH106P。将GETXH106P克隆至原核表达载体p ET30a(+),转染BL21(DE3)菌中进行表达与纯化,从而获得重组蛋白r ETXH106P。利用Western blot方法检测r ETXH106P与D型产气荚膜梭菌抗血清的反应性,并检测其对犬肾细胞系(MDCK细胞)以及小鼠的毒力。随后,将r ETXH106P与Montanide ISA 201佐剂混合乳化制备疫苗,免疫4只健康家兔,按照《中华人民共和国兽药典》(2015年版)规定的方法检测一免及二免后兔血清的中和抗体效价。结果表明,r ETXH106P为可溶性表达,通过灰度扫描,其可溶性表达量比例可达30%;该重组蛋白能与D型产气荚膜梭菌毒素抗血清反应;细胞毒性试验结果显示,100μg/m L的重组蛋白仍无细胞毒性;小鼠安全性实验结果显示,6.25×106ng/kg剂量的重组蛋白对小鼠仍无致死性;每毫升的一免抗血清可中和450~700个最小致死量(MLD)、二免抗血清可中和3000~4000个MLD的D型产气荚膜梭菌毒素;用1 MLD的D型产气荚膜梭菌毒素攻毒后,对照组家兔4/4死亡,免疫组家兔4/4保护。以上结果表明,产气荚膜梭菌r ETXH106P重组蛋白毒力基本消失,且保留了良好的免疫原性,是D型产气荚膜梭菌病基因工程亚单位疫苗的理想候选抗原蛋白。     

重组产气荚膜梭菌α毒素突变体的表达与免疫保护力评价

为获得产气荚膜梭菌α毒素(CPA)的重组突变体,并评价其毒力和免疫原性,对已知的产气荚膜梭菌CPA编码基因进行优化设计,同时引入包括第56位和第130位的天冬氨酸(D)突变为甘氨酸(G),及第275位的酪氨酸(Y)和第336位的天冬氨酸(D)突变为天冬酰胺(N)的4个氨基酸突变。此外,在该基因5'端添加Th细胞表位(T)和鞭毛蛋白(flagellin)N末端编码序列,经人工合成获得基因片段GTFNCPAm4。将GTFNCPAm4克隆至原核表达载体p ET-30a(+)中进行表达与纯化,获得重组蛋白rTF_NCPA_(m4)。利用Western blot方法检测rTF_NCPA_(m4)与产气荚膜梭菌A型毒素抗血清的反应性,并检测该蛋白的卵磷脂酶和溶血活性以及对小鼠的毒力。随后,将重组蛋白与Montanide ISA 201佐剂以1∶1(V/V)的比例混合乳化,免疫家兔,检测兔血清的中和抗体效价。二免后21 d,对家兔通过耳缘静脉注射1个MLD剂量的A型产气荚膜梭菌毒素,以检测rTF_NCPA_(m4)对家兔的免疫保护效果。结果表明,rTF_NCPA_(m4)主要以包涵体的形式表达,且能与A型产气荚膜梭菌毒素产生血清反应;体外实验显示,rTF_NCPA_(m4)无卵磷脂酶和溶血活性;小鼠安全性实验显示,5.5 mg/kg剂量的rTF_NCPA_(m4)对小鼠无致死性;免疫重组蛋白后,每毫升的一免抗血清可中和10个MLD、二免抗血清可中和40个MLD的A型产气荚膜梭菌毒素;1个MLD的A型产气荚膜梭菌毒素攻毒后,对照组家兔4/4死亡,免疫组家兔得到了100%(4/4)的保护。以上数据说明,表达的CPA重组突变体蛋白具有良好的安全性和免疫原性,为A型产气荚膜梭菌基因工程亚单位疫苗的研制提供了重要的实验数据。     

OEPR法构建含不同破伤风毒素T细胞表位的CPB表达质粒及其产物的初步鉴定

为了提高产气荚膜梭菌β毒素(CPB)亚单位疫苗的免疫效果,试验将不同破伤风毒素辅助性T细胞表位引入该蛋白前,用OEPR(Overlap Extension PCR and Recombination)法构建了8个重组表达质粒(即p Cold-CPB、p Cold-P2-CPB、p Cold-P21-P30-P2-CPB、p Cold-P32-P23-P21-P30-P2-CPB和p ET22b-CPB、p ET22b-P2-CPB、p ET22b-P21-P30-P2-CPB、p ET22bP32-P23-P21-P30-P2-CPB)。将阳性重组质粒转入到大肠杆菌中,以自诱导培养基表达目的蛋白。SDS-PAGE分析结果表明,8个重组菌均成功表达出目的蛋白,且大小均与预期一致。Western Blotting检测结果表明,重组蛋白均可被C型产气荚膜梭菌阳性血清识别。毒性试验结果表明,重组蛋白均可致死小鼠。本研究首次用OEPR法成功构建了8个含不同破伤风毒素T细胞表位的产气荚膜梭菌β毒素表达质粒,并成功表达了目的蛋白,为探索破伤风毒素辅助性T细胞表位对产气荚膜梭菌β毒素免疫效果的影响及进一步开发亚单位疫苗奠定了基础。     

重组产气荚膜梭菌ε毒素三点突变体的融合表达及其免疫活性分析

为获得并评价重组产气荚膜梭菌ε毒素(ETX)三点突变体蛋白的毒力及免疫活性,对已知的D型产气荚膜梭菌ETX编码基因进行优化设计,同时引入包括第30和196位酪氨酸突变为丙氨酸,及第106位组氨酸突变为脯氨酸共3个氨基酸突变,并在该基因5'端添加Th细胞表位(T)和鞭毛蛋白(flagellin)N末端编码序列,经人工合成获得基因片段GTFNETXm3。随后,将该基因片段克隆至原核表达载体p ET30a-(+),转染BL21(DE3)菌诱导表达、纯化,从而获得重组蛋白,进而利用Western blot方法检测重组蛋白与D型产气荚膜梭菌抗血清的反应性,并检测其对犬肾细胞系(MDCK细胞)及小鼠的毒力。最后,将重组蛋白与Montanide ISA 201佐剂混合乳化制备疫苗,免疫4只健康家兔,根据《中华人民共和国兽药典》(2015年版)规定的方法检测一免及二免后兔血清的中和抗体效价。结果显示,重组蛋白主要以包涵体的形式存在,且能与D型产气荚膜梭菌毒素抗血清反应;100μg/m L的重组蛋白未显示细胞毒性;6.25 mg/kg剂量的重组蛋白对小鼠无致死性;每毫升的一免抗血清可中和80~120个最小致死量(MLD)、二免抗血清可中和750~1100个MLD的D型产气荚膜梭菌毒素;用1个MLD的D型产气荚膜梭菌毒素攻毒后,对照组家兔4/4死亡,免疫组家兔4/4保护。试验表明,产气荚膜梭菌ETX三点突变体的毒力基本消失,且保留了良好的免疫原性,是D型产气荚膜梭菌病基因工程亚单位疫苗的理想候选抗原蛋白。     

产气荚膜梭菌α毒素突变体的表达及免疫保护力评价

对已知的产气荚膜梭菌CPA编码基因进行优化设计,同时引入包括第56和130位的天冬氨酸(D)突变为甘氨酸(G),及第275位的酪氨酸(Y)和第336位的天冬氨酸(D)突变为天冬酰胺(N)的4个氨基酸突变,经人工合成获得基因片段Gcpam4。将Gcpam4克隆至原核表达载体pET-30a(+)中进行表达与纯化,获得重组蛋白rCPAm4。利用Western blot方法检测rCPAm4与产气荚膜梭菌A型毒素抗血清的反应性,并采用小鼠检测纯化蛋白的毒力。随后,将rCPAm4与Montanide ISA 201佐剂以1∶1的比例混合乳化制备疫苗,免疫家兔,按照《中华人民共和国兽药典》(2015年版)规定的方法检测兔血清的中和抗体效价。二免后21d,对家兔通过耳缘静脉注射1个家兔MLD剂量的A型产气荚膜梭菌毒素,以检测rCPAm4对家兔的免疫保护效果。结果表明,rCPAm4主要以包涵体的形式表达,且能与产气荚膜梭菌A型毒素抗血清反应;小鼠安全性试验显示,5.5mg/kg剂量的rCPAm4对小鼠仍无致死性;免疫rCPAm4后,每毫升的一免抗血清可中和10～20个小鼠MLD、二免抗血清可中和30～50个小鼠MLD的A型产气荚膜梭菌毒素;1个家兔MLD的A型产气荚膜梭菌毒素攻毒后,对照组家兔100%死亡,免疫组家兔得到了100%的保护。以上结果表明,rCPAm4具有良好的安全性和免疫原性,从而为A型产气荚膜梭菌基因工程亚单位疫苗的研制提供了重要的试验数据。     

产气荚膜梭菌重组ε毒素突变体的免疫保护力评价

旨在获得产气荚膜梭菌ε毒素的重组突变体,并评价其毒力及免疫原性。对已知的D型产气荚膜梭菌ε毒素编码基因进行了优化设计和人工合成,同时引入3个氨基酸点突变:第30和196位酪氨酸突变为丙氨酸,第106位组氨酸突变为脯氨酸。将该基因片段克隆至原核表达载体pET30a-(+)中进行表达,并纯化。利用Western blot方法检测纯化蛋白质与D型产气荚膜梭菌ε毒素抗血清的反应性,并检测其对小鼠的毒力。随后,以纯化的重组蛋白质免疫兔,根据《中华人民共和国兽药典》(2015年版)规定的方法检测兔血清的中和抗体效价。结果表明,ε毒素的重组突变体为可溶性表达,通过灰度扫描,其表达量比例可达40%;该蛋白质能与D型产气荚膜梭菌ε毒素抗血清反应,小鼠安全试验显示,6.25×106 ng·kg-1的蛋白质仍无毒力;免疫兔血清对D型产气荚膜梭菌ε毒素的中和效价在一免后可达50~60最小致死量(MLD),二免后可达400~450 MLD;用1个MLD的D型产气荚膜梭菌毒素攻毒后,对照组4/4死亡,免疫组得到保护。由此表明,产气荚膜梭菌重组ε毒素突变体无毒力且保留了良好的免疫原性,为D型产气荚膜梭菌病新型疫苗的研制提供了重要的实验数据。     

腐败梭菌α毒素和产气荚膜梭菌ε毒素的 共表达及其免疫效力评价

为获得腐败梭菌α毒素和D型产气荚膜梭菌ε毒素的共表达产物,并鉴定其致死活性和反应原性,评价其免疫保护效力,利用PCR扩增腐败梭菌α毒素和产气荚膜梭菌ε毒素基因Gcsa和Gcpe并克隆至pETDuet-1质粒,转化E.coli BL21(DE3),自诱导培养基诱导这2段基因共表达;用SDS-PAGE和Western-blot以及小鼠毒性试验、抗毒素血清中和试验对表达产物进行鉴定;将诱导后的大肠杆菌灭活,制成铝佐剂疫苗1 m L/只皮下注射免疫家兔2次,测定免疫血清中和抗体效价,用1 MLD的腐败梭菌毒素和D型产气荚膜梭菌毒素分别攻击。结果显示,所构建的E.coli BL21(pETDuet-Gcsa-Gcpe)可以同时表达Gcsa和Gcpe,表达产物能够与腐败梭菌和D型产气荚膜抗毒素血清反应;且具有小鼠致死毒性,只有用2种抗毒素一同作用,才能将其毒性中和;制成灭活疫苗免疫家兔,免疫血清对腐败梭菌毒素的中和抗体效价为2 MLD/0.1 m L,对D型产气荚膜梭菌毒素的中和抗体效价≥50 MLD/0.1 m L;用2种毒素攻击,免疫组家兔全部保护,对照组全部死亡,达到《中华人民共和国兽药典》(2015版)效力检验标准。结果表明,所构建的表达载体可以实现α毒素和ε毒素的活性共表达,本研究为腐败梭菌和产气荚膜梭菌的多联基因工程灭活疫苗的研究提供了实验基础。     

产气荚膜梭菌α毒素C末端与中和抗原表位的串联表达及免疫保护性分析

为获得产气荚膜梭菌α毒素(CPA)的C末端(CPAC)与中和抗原表位NE(ARGFAK)的串联融合蛋白并评价其免疫原性,对已知的A型产气荚膜梭菌CPAC及NE的编码基因进行优化设计,并将两个基因的三拷贝序列串联,经人工合成获得基因片段GCPAC3NE3。将该片段克隆至原核表达载体p ET30a(+)中进行表达与纯化,获得重组蛋白。利用Western blot方法检测重组蛋白与A型产气荚膜梭菌毒素抗血清的反应性。随后,以纯化的重组蛋白免疫家兔,根据《中华人民共和国兽药典》(2015年版)规定的方法检测家兔血清的中和抗体效价。在二免后21 d,以1个MLD的A型产气荚膜梭菌毒素对家兔进行攻毒。结果表明重组蛋白主要以包涵体的形式存在表达且能与A型产气荚膜梭菌毒素抗血清反应。每毫升的一免抗血清可中和40个最小致死量(MLD)、二免抗血清可中和80个MLD的A型产气荚膜梭菌毒素;1个MLD的A型产气荚膜梭菌毒素攻毒后,对照组4/4死亡,免疫组得到了100%(4/4)的保护。以上结果说明,重组蛋白具有良好的免疫原性,从而为A型产气荚膜梭菌病基因工程疫苗的研制提供了重要的实验数据。     

产气荚膜梭菌α毒素C末端的三拷贝串联表达与免疫原性分析

本研究旨在获得产气荚膜梭菌α毒素（CPA） C末端（第247－370位氨基酸,CPA_C）三拷贝串联融合蛋白,并评价其免疫原性。对已知的A型产气荚膜梭菌CPA_C编码基因（GenBank登录号：AY823400.1）进行优化设计,以同向串连的方式串联成三拷贝基因（GCPA_C3）,片段之间用柔性氨基酸linker （GGGS）连接,经人工合成后克隆至原核表达载体pET-30a （＋）中进行表达与纯化,获得CPA_C的三拷贝重组蛋白（rCPA_C3）。利用Western blotting方法检测rCPA_C3与A型产气荚膜梭菌毒素抗血清的反应性。将rCPA_C3与Montanide ISA 201佐剂混合乳化制备疫苗,免疫4只健康家兔,检测一免及二免后兔血清的中和抗体效价。在二免21 d后,对家兔经耳缘静脉注射1个家兔最低致死剂量（MLD）的A型产气荚膜梭菌毒素,检测rCPA_C3对家兔的免疫保护效果。结果显示,rCPA_C3主要以包涵体的形式表达,且能与A型产气荚膜梭菌毒素抗血清反应;每毫升的一免抗血清可中和30~50个、二免抗血清可中和70~100个小鼠MLD的A型产气荚膜梭菌毒素。采用1个家兔MLD的A型产气荚膜梭菌毒素攻毒后,对照组家兔100%（4/4）死亡,免疫组得到了100%（4/4）的保护。以上结果说明,rCPA_C3具有良好的免疫原性,为A型产气荚膜梭菌病基因工程疫苗的研制提供了重要的试验数据。     

产气荚膜梭菌α毒素C末端的三拷贝串联表达与免疫原性分析

本研究旨在获得产气荚膜梭菌α毒素(CPA)C末端(第247-370位氨基酸,CPA_C)三拷贝串联融合蛋白,并评价其免疫原性。对已知的A型产气荚膜梭菌CPAC编码基因(GenBank登录号:AY823400.1)进行优化设计,以同向串连的方式串联成三拷贝基因(GCPA_(C3)),片段之间用柔性氨基酸linker(GGGS)连接,经人工合成后克隆至原核表达载体pET-30a(+)中进行表达与纯化,获得CPA_C的三拷贝重组蛋白(rCPA_(C3))。利用Western blotting方法检测rCPA_(C3)与A型产气荚膜梭菌毒素抗血清的反应性。将rCPA_(C3)与Montanide ISA 201佐剂混合乳化制备疫苗,免疫4只健康家兔,检测一免及二免后兔血清的中和抗体效价。在二免21d后,对家兔经耳缘静脉注射1个家兔最低致死剂量(MLD)的A型产气荚膜梭菌毒素,检测rCPA_(C3)对家兔的免疫保护效果。结果显示,rCPA_(C3)主要以包涵体的形式表达,且能与A型产气荚膜梭菌毒素抗血清反应;每毫升的一免抗血清可中和30～50个、二免抗血清可中和70～100个小鼠MLD的A型产气荚膜梭菌毒素。采用1个家兔MLD的A型产气荚膜梭菌毒素攻毒后,对照组家兔100%(4/4)死亡,免疫组得到了100%(4/4)的保护。以上结果说明,rCPA_(C3)具有良好的免疫原性,为A型产气荚膜梭菌病基因工程疫苗的研制提供了重要的试验数据。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

乳酸杆菌作为益生菌广泛用于人和动物。本文综述了乳酸杆菌改善宿主健康的机制。乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道。文章重点讨论了乳酸杆菌表面成分（表面蛋白、脂磷壁酸和肽聚糖）与肠道受体（Ｃ型凝集素受体、Ｔｏｌｌ样受体和 Ｎｏｄ样受体）,阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.     

Mechanism of Action of Probiotic Function of Lactobacilli

乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制.     

Evaluation of serum concentrations of biomarkers of skeletal metabolism and results of radiography as indicators of severity of osteochondrosis in foals

OBJECTIVE: To determine whether serum concentrations of biomarkers of skeletal metabolism can, in conjunction with radiographic evaluation, indicate severity of osteochondrosis in developing horses. ANIMALS: 43 Dutch Warmblood foals with varying severity of osteochondrosis. PROCEDURE: 24 foals were monitored for 5 months and 19 foals were monitored for 11 months. Monthly radiographs of femoropatellar-femorotibial and tibio-tarsal joints were graded for osteochondral abnormalities. Serial blood samples were assayed for 8 cartilage and bone biomarkers. At the end of the monitoring period, foals were examined for macroscopic osteochondrosis lesions. RESULTS: Temporal relationships were evident between certain serum biomarkers and osteochondrosis severity in foals during their first year. Biomarkers of collagen degradation (collagenase-generated neoepitopes of type-II collagen fragments, type-I and -II collagen fragments [COL2-3/4C(short)], and cross-linked telopeptide fragments of type-I collagen) and bone mineralization (osteocalcin) were positive indicators of osteochondrosis severity at 5 months of age. In foals with lesions at 11 months of age, osteochondrosis severity correlated negatively with COL2-3/4C(short) and osteocalcin and positively with C-propeptide of type-II procollagen (CPII), a collagen synthesis marker. Radiographic grading of osteochondrosis lesions significantly correlated with macroscopic osteochondrosis severity score at both ages and was strongest when combined with osteocalcin at 5 months and CPII at 11 months. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of serum biomarkers to indicate osteochondrosis severity appears to depend on stage of disease and is strengthened with radiography. In older foals with more permanent lesions, osteochondrosis severity is significantly related to biomarker concentrations of decreased bone formation and increased cartilage synthesis.