浅析影响血凝和血凝抑制试验的因素

血凝和血凝抑制试验是兽医实验室检测禽流感、新城疫免疫抗体的最常用方法之一.它也是检查防疫质量的重要依据.但在实验操作过程中,经常受到各种因素的影响,造成实验结果误差.     

保存红细胞与现配红细胞在血凝与血凝抑制中的对比试验

随着实验室检测血清样本数量的增加,延长红细胞的保存时间已成为当前血凝和血凝抑制试验中困扰已久的问题。该试验以新配制的缓冲液稀释保存长达6个月的鸡红细胞不影响血凝和血凝抑制试验结果,这极大方便了实验室及现场血凝、血凝抑制试验的操作。     

浅谈影响禽流感血凝和血凝抑制试验结果的因素

禽流感血凝和血凝抑制试验是评价禽流感疫苗免疫效果最常用的方法,具有操作简单、结果判定快速且不需要特殊的仪器设备等优点,但该试验在实际操作中受多种因素的影响,笔者结合临床工作经验,初步探讨影响禽流感血凝和血凝抑制试验结果的因素。     

禽流感血凝和血凝抑制试验的影响因素分析

在进行禽流感血凝和血凝抑制试验时,要严格按照操作规程,考虑多方面的因素,尤其要注意各步骤操作的细节,认真细致地进行操作,尽量消除不利影响,减少误差,确保试验结果的准确性.     

浅析影响血凝和血凝抑制试验的因素

血凝和血凝抑制试验是化验室中进行动物疫病诊断和免疫监测最常用的试验方法之一，如禽流感、口蹄疫等疫病的化验室诊断或免疫监测在基层多使用这种试验方法。今年在我国其它省市发生多起禽流感等重大动物疫病威胁我省我市的情况下，省、市、县等各级畜牧兽医部门都对禽流感进行了大量的化验室监测，运用和准确掌握血凝和血凝抑制试验对禽流感等重大动物疫病的诊断和免疫监测就显得尤为重要。但血凝和血凝抑制试验方法在操作中常有较多的影响因素，容易造成试验结果偏差，甚至误判。现将这种实验方法操作中影响因素浅析如下。     

浅谈禽流感血凝和血凝抑制试验注意事项

禽流感血凝和血凝抑制试验可用于血清中抗体水平的监测,也可用于判断未使用疫苗群体的感染状态.这两种试验在实践中应用的比较多,但也容易出错,现对该试验过程中应注意的事项做一探讨.     

影响禽流感血凝-血凝抑制试验的主要因素

禽流感血凝-血凝抑制试验因其具有简便、快速、准确、实用的特点,在县级兽医实验室被广泛应用.但在试验过程中,人为因素的影响很大,常常因为操作不规范等,导致试验结果不准确,甚至失败.     

血凝和血凝抑制试验常见问题及解决方法

血凝和血凝抑制试验是目前我国各地开展疫病诊断、流行病学调查、免疫程序制定及免疫效果监测等的主要手段之一。由于其涉及红细胞凝集及抗原抗体的特异性反应,操作过程常受多种因素影响,容易造成偏差。文章针对血凝和血凝抑制试验中常见问题,从血凝和血凝抑制试验的缓冲体系、血凝板或微量振荡器、1%鸡红细胞悬液配制等方面进行分析,并总结经验和解决方法。     

血凝和血凝抑制试验的影响因素分析

血凝和血凝抑制试验在疫病防控中应用非常广泛,但影响试验结果的因素较多。针对试验中缓冲液、红细胞、抗原、样品、温度和时间、试验器材和耗材、结果判定等因素对试验的影响进行了分析。     

禽流感血凝和血凝抑制试验的影响因素分析

禽流感严重危害我国的养禽业,疫苗免疫是目前预防和控制禽流感发生的最有效手段,免疫后抗体水平的高低直接关系到实际的免疫效果,因而免疫抗体监测操作技术的准确性、有效性、可靠性对禽流感防控工作起着不可忽视的作用。禽流感免疫抗体水平监测一般采用血凝和血凝抑制试验(HA-HI试验),经济、操作简便和容易量化是该试验方法的优点,但影响试验结果的因素也较多,导致HA-HI试验结果失真,下面将就禽流感血凝和血凝抑制试验的影响因素浅析如下。     

影响血凝试验和血凝抑制试验的因素分析

血凝试验和血凝抑制试验是检验新城疫、禽流感等疫病抗体效价的一种常用方法,该方法具有所需器材简单、操作方便、试验结果判定快速等优点,对保护动物健康和减少养殖损失有重要的临床指导意义。但该试验影响因素很多,常导致试验结果不准确。文章从试验器材、稀释液、抗原和阳性血清、待检血清、红细胞及其他影响因素进行综合分析,旨在避免或减少不利因素的影响,提高试验的准确性。     

Specificity of purified protein derivative extracts from ten species of Mycobacteria killed with phenol in the haemagglutination and haemagglutination inhibition test

The specificity of purified protein derivative (PPD) extracts from 10 species of Mycobacteria killed with phenol was evaluated using the haemagglutinin (HA) and haemagglutination inhibition (HI) tests. The HA test showed many cross-reactions with homologous and heterologous antisera. In the HI test, many antisera cross-reacted with most PPD extracts. The PPD extracts from Mycobacterium foruitum and M. smegmatis were the most specific. It was concluded that PPD extracted from unheated bacilli was not sufficiently specific for use in HI tests.     

The Development and Application of the Latex Agglutination Test to Detect Serum Antibodies against Japanese Encephalitis Virus

The attenuated SA14-14-2 strain of Japanese encephalitis virus (JEV) was cultured in BHK-21 cells. The viral supernatant was purified and concentrated with PEG (MW 20 000). A suitable concentration of JEV antigen was used to sensitize latex to prepare the latex antigen. The specificity, sensitivity and stability of the antigen were assessed. A latex agglutination test (LAT) was developed for rapidly detecting antibody against JEV infection. The LAT and haemagglutination inhibition (HI) assay were compared by simultaneously testing 35 porcine serum samples from five farms. Ninety per cent (20/23) of the samples were seropositive by both assays. No significant difference was found between the two methods (p > 0.05). Furthermore, when 1613 porcine sera from 120 farms were tested by LAT, the number of positive sera was 652, while that of negative sera was 961, ranging from 20% to 50% positive throughout the year. These results indicate that LAT is an appropriate candidate method for epidemiological surveys for and diagnosis of Japanese encephalitis.     

Evaluation of enzyme-linked immunosorbent assays based on monoclonal antibodies for the serology and antigen detection in canine parvovirus infections

An enzyme-linked immunosorbent assay (ELISA) system was developed for the detection of canine parvovirus (CPV) or CPV antigen in dog faeces and two other ELISA systems were developed for the detection of CPV-specific antibodies in dog sera. The ELISA's were based on the use of CPV-specific mouse monoclonal antibodies, which recognise different epitopes of the haemagglutinin of CPV and which also neutralise the virus. A double antibody sandwich (DAS) ELISA for the detection of CPV in dog faeces was compared with the haemagglutination (HA) test. The DAS-ELISA proved to be more specific, sensitive and easier to perform than the HA assay. An indirect ELISA and a competitive ELISA for the detection of CPV-specific antibodies in dog sera were compared with the haemagglutination inhibition (HI) test. Both ELISA systems proved to be specific and easy-to-use methods for the detection of CPV-specific antibodies. The indirect ELISA, specially, proved to be more sensitive than the HI test. The higher sensitivity and specificity of the ELISA's as compared to HA and HI tests, and their ease of use, make them suitable for routine use in the serology and diagnosis of CPV infections.     

Detection of challenge virus in fetal tissues by nested PCR as a test of the potency of a porcine parvovirus vaccine

To estimate the potency of a porcine parvovirus (PPV) vaccine, three vaccinated and three non-vaccinated pregnant gilts were infected with PPV and the distribution of the virus was studied in the tissues of their 51 fetuses. Virus detection was attempted using haemagglutination (HA) and immunofluorescence (IF) assays, as well as by standard (single) and nested polymerase chain reactions (PCR). None of the detection methods yielded positive results when used to test for the presence of virus in suspensions of organs from the fetuses from the vaccinated gilts. However, the virus was detected in the fetuses from non-vaccinated gilts as follows: HA was positive in 14 cases out of 23 (60.8%), IF in 16/23 (69.5%), standard PCR in 12/20 (60%), and the nested PCR in 19/23 (82.6%). Although the correlation among the results of various methods of virus detection was rather close (r<0.83), the sensitivity of the nested PCR was the highest, both when testing dilutions of PPV and when analysing the fetal organs. The nested PCR therefore provides a reliable approach for studies of virus distribution in fetal organs, with special reference to potency tests on vaccines.     

3种犬细小病毒感染诊断方法比较

本研究应用犬细小病毒抗原快速检测试剂盒、血凝/血凝抑制试验和PCR方法对120份具有腹泻/呕吐症状的患犬粪便样本进行了犬细小病毒检测。结果显示,3种方法检测阳性份数分别为60,49,68。犬细小病毒抗原快速检测试剂盒与血凝/血凝抑制(HA/HI)试验相比较,敏感性、特异性及总符合率分别为100.0%,84.5%,90.8%;与PCR法相比较,敏感性、特异性及总符合率分别为85.3%,96.2%,90.0%。从试验结果看,HA/HI法具有较高的特异性,但敏感性较低;PCR具有高度敏感性和特异性,但不适合临床推广;细小病毒抗原快速检测试剂盒,在正确操作下结果可靠,是临床诊断犬细小病毒感染的首选方法。     

The sensitivities of various erythrocytes in a haemagglutination assay for the detection of psittacine beak and feather disease virus

The erythrocytes of various species were tested in psittacine beak and feather disease (PBFD) virus haemagglutination (HA) and haemagglutination inhibition assays to determine which are suitable for use in these assays. HA activity was observed for erythrocytes of the salmon-crested cockatoo, the sulphur-crested cockatoo, the umbrella cockatoo, the goffin's cockatoo and the cockatiel, with differences amongst individuals within species, but not for erythrocytes of humans, the pig, the guinea pig, the chicken, the goose, the rose-ringed parakeet or the budgerigar. Anti-PBFD virus rabbit sera inhibited the virus-induced agglutination of erythrocytes, confirming the specificity of HA activity. This suggests that selection of suitable psittacine species as well as suitable individuals within a species is necessary when obtaining erythrocytes for the PBFD virus HA assay.     

Dot-enzyme linked immunosorbent assay for demonstration of Newcastle disease virus infection

Dot-enzyme linked immunosorbent assay (ELISA) was standardised to detect Newcastle disease virus (NDV) specific antigen in chicken tissues, embryos and allantoic fluid samples. Samples positive by virus isolation were also found positive by haemagglutination (HA) and haemagglutination inhibition (HI) tests and by dot-ELISA but negative samples were found negative by all the serological tests used. Dot-ELISA was able to detect 0.25-0.50 HA units of virus. The emerging utility of dot-ELISA for diagnosis of Newcastle disease virus infection has been discussed.     

In vitro adhesion of K88ab-, K88ac- and K88ad-positive Escherichia coli to intestinal villi, to buccal cells and to erythrocytes of weaned piglets

The phenotype of 21 weaned piglets, concerning adhesion of Escherichia coli possessing K88ab, K88ac or K88ad fimbriae to pig cells, was determined in an in vitro assay. Comparison was made with adhesion of these three K88 variant strains to buccal mucosal epithelial cells and to erythrocytes (haemagglutination) in the same piglets. Whereas adhesion of the three K88 variant strains to intestinal villi was piglet specific, buccal cell adhesion (BCA) and haemagglutination (HA) were not. The K88ab strain was weakly adhesive or non-adhesive in the BCA and negative in the HA test. K88ac strains consistently gave negative and K88ad consistently gave positive results in both assays. After washing the bacteria with phosphate-buffered saline, the K88ab strain revealed a positive HA test. Neither the BCA, nor HA test can be used to determine the pig intestinal adhesive phenotype.     

Bovine rotavirus diagnosis: comparison of various antigens and serological tests

Agar gel immunodiffusion (AGID) and counter-immunoelectrophoresis (CIEP), complement fixation (CF), radio-immunoassay (RIA), haemagglutination (HA) and haemagglutination inhibition (HI) tests were compared in their efficiency for the detection of bovine rotavirus antigens and antibodies. As a test for antigen using hyperimmune serum, CIEP was found to have advantages over AGID by being more rapid as well as approximately four times more sensitive regardless of whether the antigen was of faecal or tissue culture origin. The CF test was more sensitive than either of the immunodiffusion procedures studied for antigen detection, but was more tedious to perform and of limited use as some faecal samples exhibited anti-complementary activity. For measurement of rotavirus antibody the radio-immunoassay (RIA) was the most sensitive technique and the CIEP least sensitive. Using the RIA a limited survey of cattle demonstrated that approximately 75% of the animals tested possessed specific antibody to rotavirus.