Response of pups with maternal derived antibody to modified-live canine parvovirus vaccine

The AA reports the results of vaccination against canine parvovirus (CPV) of pups with maternal antibody, utilizing a modified-live virus (MLV) CPV vaccine having a titer of 10⁷ TCID₅₀/dose. This vaccine was shown to be effective also when HI antibody titers of pups were ≤ 1:80.     

Immunization of pups with maternally derived antibodies to canine parvovirus (CPV) using a modified-live variant (CPV-2b)

The results of vaccination trials carried out on pups with maternally derived antibodies (MDA) to canine parvovirus (CPV), using a modified-live CPV-2b variant vaccine (29-97/40 strain), are reported. The vaccine was able to overcome the obstacle of MDA, and to elicit protective immunity in 100% of the pups whose antibody titres were 1:10-1:40, 83% of the pups with titres of 1:80, 57% of the pups with titres of 1:160, and even in 60% of the pups with antibody titres of 1:320.     

Response of pups to modified-live canine parvovirus component in a combination vaccine

Twenty-eight pups from a general pet population were vaccinated for canine parvovirus (CPV) with a combination vaccine every 3 weeks until the pups were 11 to 16 weeks old. Canine parvovirus antibody titers were measured by serum neutralization before each vaccination and greater than or equal to 2 weeks after the final vaccination. Eighteen pups that initially were seronegative for CPV seroconverted after 1 to 3 doses of modified-live virus CPV vaccine administered when the pups were between 8 and 16 weeks old; 16 of 18 seroconverted after the 1st dose. Of 10 pups that were seropositive for CPV at initial examination, 7 did not develop protective titers after 3 doses of vaccine, with the last dose given when the pups were 14 to 16 weeks old. Maternally derived antibody was the primary cause of vaccination failure.     

犬细小病毒基因疫苗单克隆抗体的制备

为获得可用于犬细小病毒(CPV)感染的治疗和快速诊断的单克隆抗体,从病料中分离了1株犬细小病毒,经PCR扩增VP1全基因并进行序列分析,确定为CPV-2 a型。再将VP1基因克隆到真核表达质粒pc DNA3中,构建了基因疫苗pc DNA3-VP1。用该基因疫苗免疫BALB/c小鼠3次后,取抗体效价高的两只小鼠脾细胞与SP2/0细胞融合,经间接ELISA检测,结果获得了3株杂交瘤细胞株,该3株单抗与犬、猫细小病毒能发生反应,均不与犬瘟热病毒、流感病毒和犬腺病毒发生反应,诱生的腹水可体外中和犬细小病毒,其中两株单抗的中和效价为1∶256,1株单抗腹水的中和效价低于1∶128。结果表明,该CPV VP1基因疫苗可制备具有一定中和效价的CPV单克隆抗体。     

猪繁殖与呼吸综合征病毒弱毒株活疫苗抗体应答水平的观察

用本厂生产的猪繁殖与呼吸综合征(PRRS)活疫苗及病毒液分别以不同剂量给PRRS阴性猪注射，并在不同时间采血测其相应的抗体水平，比较不同剂量抗体水平维持时间。结果表明，猪注射该疫苗后14d即可产生较高的抗体水平，并在21—35d达到高峰，42d略有下降，70d时抗体水平仍为阳性，104d仍有85％以上的猪抗体水平阳性。     

Preliminary development of a live attenuated canine parvovirus vaccine from an isolate of British origin

Canine parvovirus isolated from a case of haemorrhagic enteritis in a breeding kennel in England was passaged and cloned in cultured feline and canine cells. No significant evidence of pathogenicity was found during six serial passages of the modified virus back through young dogs. The attenuated virus was excreted by inoculated animals and spread rapidly to uninoculated animals held in contact. When high titre attenuated virus was given to the six-week-old offspring of a seropositive dam a prompt seroconversion was observed. When the attenuated virus was used as an experimental vaccine in 108 pups in an infected breeding colony a highly significant improvement was obtained in the accumulated morbidity and mortality compared with a parallel group vaccinated with modified live feline panleucopenia virus.     

狐犬瘟热细小病毒性肠炎和脑炎三联活疫苗免疫效力试验

我国养狐业发展迅速,目前全国狐存栏数已达2 000多万只,形成了一新兴产业.据我们调查分析,目前危害养狐业主要的疫病有犬瘟热、细小病毒性肠炎和脑炎.     

First detection of canine parvovirus type 2c in pups with haemorrhagic enteritis in Spain

Canine parvovirus type 2 (CPV-2), the aetiological agent of haemorrhagic enteritis in dogs, includes three antigenic variants, types 2a, 2b and 2c. CPV-2c has been detected initially in Italy and subsequently in Vietnam. We report the first identification of this novel antigenic variant in Spain, where it caused an outbreak of fatal enteritis in basset hound pups in association with canine coronavirus type I and type II. We suggest that this new antigenic variant of CPV-2 could spread throughout Europe and that there is a subsequent need to update current CPV vaccines.     

猪细小病毒N株弱毒疫苗区域试验

用三批PPV-N株弱毒疫苗分别在三个规模化猪场进行了较大范围的区域试验,共免疫后备母猪32930头,观察其安全性和免疫效力.结果表明,三批苗均能使豚鼠产生良好的抗体反应.猪只注苗后食欲、体温均正常,无任何不良临床反应.平均每胎产健活仔10.96头,而死胎仅为0.52头,说明PPV-N株弱毒疫苗是预防猪细小病毒感染安全、有效的弱毒疫苗.     

番鸭细小病毒和鹅细小病毒二联弱毒细胞苗的研究

应用适应于番鸭胚成纤维细胞(MDEFC)上繁殖,并产生细胞病变的鹅细小病毒(GPV)弱毒疫苗株与番鸭细小病毒(MPV)弱毒疫苗,按适当比例混合,试制了MPV-GPV二联弱毒细胞苗,并测定了各项免疫指标.结果显示试制出的二联苗对1日龄雏番鸭具有良好的安全性和遗传稳定性;免疫后5 d和7 d攻击GPV强毒,保护率分别为75%和100%,同时免疫后7 d血清中MPV-胶乳凝集抑制(LPAI)抗体效价均大于21,21～28 d抗体达高峰,有效免疫期超过60 d.疫苗于-20℃保存期大于12个月.上述结果表明,二联弱毒细胞苗安全有效.     

Observations on the use of an inactivated canine parvovirus vaccine

Data are presented on studies of field and experimental use of a formalin-inactivated canine parvovirus vaccine. There was an absolute correlation between a single successful vaccination and subsequent protection against clinical disease. Unsuccessful vaccinations were consistently associated with the presence of maternal antibody at the time of vaccination. The vaccine induced an antibody response within two days and anamnestic responses within 24 hours. It is suggested that a single successful vaccination probably protects against clinical parvovirus disease for life.     

犬细小病毒抗体间接ELISA检测方法的建立

利用本实验室建立的昆虫细胞/杆状病毒表达系统表达犬细小病毒病毒样颗粒（CPV-VLPs）,采用硫酸铵沉淀、蔗糖密度梯度离心对表达的CPV-VLPs进行纯化,用电子显微镜、SDS-PAGE及Western-blotting方法检测纯化效果。以纯化的CPV-VLPs作为包被抗原建立CPV间接ELISA检测方法,对各反应条件进行优化并分析其特异性、敏感性、重复性。结果显示,CPV-VLPs经过纯化后纯度可达到95%以上;优化的ELISA最佳工作条件为：纯化抗原包被浓度为5.0mg/L,4℃包被过夜;1%BSA,37℃封闭2h;待检血清1∶40稀释,37℃孵育1.5h;HRP标记的酶标二抗1∶20 000稀释,37℃孵育1h;TMB室温避光显色30min;确定的血清阴性阳性临界值D450nm值为0.264。该方法可特异性检测犬细小病毒阳性血清,与犬瘟热、犬传染性肝炎、犬冠状病毒病、狂犬病阳性血清均不发生反应。该方法的敏感性为1∶640,批内重复试验变异系数小于6%,批间重复试验变异系数小于8%。42份临床血清样本的检测结果表明,与血凝抑制试验的符合率为90.48%。     

Experiments with a homologous,inactivated canine parvovirus vaccine in vaccination programmes for dogs

Summary

The significance of canine parvovirus (CPV) infections as a permanent threat to susceptible dogs, in particular pups, made the authors develop three liquid homologous inactivated adjuvant CPV vaccines that were compatible with existing canine vaccines and could he incorporated in current vaccination programmes. One vaccine (Kavak Parvo) contained only the CPV component, the second product (Kavak i‐LP) also contained two inactivated leptospiral antigens, and the third vaccine (Kavak i‐HLP) contained in addition an inactivated canine hepatitis virus.

This paper reports on the studies conducted to test the safety and efficacy of the three products. They were used as such and as diluents for freeze dried vaccines containing live attenuated measles, distemper, and hepatitis viruses. The study was performed in a breeding kennel where all dogs were free from CPV antibodies and the nonvaccinated sentinels remained so for the course of the study. All vaccines proved to be safe in dogs of all ages, including pregnant bitches. The efficacy of the CPV component was studied both by monitoring antibody titres for more than a year and by challenge exposure of some dogs to virulent CPV. The results obtained from these studies prove that the CPV component used in the three vaccines can be incorporated as indicated in the recommended canine vaccination programmes. The observations that both the inactivated CPV and hepatitis components do induce an active immunity in pups that are still protected by low levels of maternally derived antibodies against these viruses, make those vaccines very suitable in breeding kennels. Additional studies on a comparative basis are being continued in endemically CPV infected breeding kennels to quantify the significance of these observations in these special conditions.     

Three-year serologic immunity against canine parvovirus type 2 and canine adenovirus type 2 in dogs vaccinated with a canine combination vaccine

A group of client-owned dogs and a group of dogs at a commercial kennel were evaluated for duration of antibody responses against canine parvovirus type 2 (CPV-2) and canine adenovirus type 1 (CAV-1) after receiving a combination vaccine containing recombinant canarypox-vectored canine distemper virus (CDV) and modified-live CPV-2, CAV-2, and canine parainfluenza virus, with (C6) or without (C4) two serovars of Leptospira (Recombitek C4 or C6, Merial). Duration of antibody, which correlates with protective immunity, was found to be at least 36 months in both groups. Recombitek combination vaccines can confidently be given every 3 years with assurance of protection in immunocompetent dogs against CPV-2 and CAV-1 as well as CDV. This allows this combination vaccine, like other, similar modified- live virus combination products containing CDV, CAV-2, and CPV-2, to be administered in accordance with the recommendations of the American Animal Hospital Association Canine Vaccine Task Force.