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1.
Akabane virus was shown to lyse as well as to agglutinate pigeon erythrocytes. The hemolytic activity of the virus was markedly enhanced by repeated freeze-thawing, but its hemagglutinating activity was not affected. Hemolysis (HL) with the virus, like its hemagglutination, was affected by the NaCl concentration as well as by the pH of the diluent. HL was markedly affected by the incubation temperature, but hemagglutination (HA) was not; HL activity was highest at 37°C, somewhat lower at 25°C, very low at 4°C, and did not occur at 0°C. While pigeon erythrocytes were positive for both HL and HA, goose erythrocytes were positive for HA but negative for HL. Erythrocytes from cattle, sheep, rabbits, guinea pigs, mice and day-old chickens were tested for HA as well as for HL activity with negative results. A linear relationship was shown, in a wide range of the virus concentrations, between the percent HL and the virus concentration, as expressed on a logarithmic scale. Based on these findings we developed an assay method for Akabane virus hemolysin. Analysis by CsCl equilibrium density gradient centrifugation indicated the hemolytic as well as the hemagglutinating activity to be structurally associated with the virion. Scanning electron microscopy of pigeon erythrocytes undergoing HL with the virus revealed the appearance of a depressed area with a hole on the cell surface. The hemolytic activity of the virus was specifically inhibited by antisera to the virus and an HL-inhibition test was developed.  相似文献   

2.
The hemagglutinating activity and serological properties of three strains of rabbit hemorrhagic disease virus, Chinese, Korean and Shizuoka, which was first isolated in Japan, were examined by hemagglutination (HA) and cross hemagglutination inhibition (HI) test with human erythrocytes. Similar results were observed between the Chinese and Korean strains, both of which gave positive HA at 4 degrees C with O, A, B and AB, and at 22 degrees C with B and AB blood groups. In the Shizuoka strain, positive HA was observed at 4 degrees C with O, A, B and AB, at 22 degrees C with A, B And AB, and at 37 degrees C with B blood group. In experimentally infected rabbits, HI antibody in these animals showed a titer of 16,384 or 32,768 at 4 weeks after inoculation. No serological difference was observed in three strains by cross HI test.  相似文献   

3.
从某一已免疫禽流感的种鹅场采取30份血样，分别以健康鸡红细胞悬液和健康皖西白鹅红细胞悬液为指示剂，对30份血样进行禽流感血凝和血凝抑制试验。结果：用鸡红细胞悬液作指示剂进行血凝试验，测出抗原4HAU为1：32；用鹅红细胞悬液作指示剂进行血凝试验，测出抗原4HAU为1：8以1：32倍数稀释抗原，分别用鸡红细胞和鹅红细胞悬液作指示剂进行血凝抑制试验，测出30份鹅血清禽流感H5免疫抗体效价的平均值分别为2^5.8和2^3.9；以1：8倍数稀释抗原，用鹅红细胞悬液作指示剂进行血凝抑制试验，测出30份鹅血清禽流感免疫抗体的平均效价为2^5.1。  相似文献   

4.
Seventy-two isolates of Haemophilus paragallinarum were serotyped according to the Page scheme, using a new hemagglutination-inhibition (HI) test. The results were compared with the plate agglutination method conventionally used in the Page scheme. The HI test used washed cells of H. paragallinarum, glutaraldehyde-fixed chicken erythrocytes, and rabbit antisera originally produced for the agglutination method. For 49 of the isolates, there was complete correlation between the results of the HI serotyping test and the previously performed agglutination test--23 were serovar A, two were serovar B, and 24 were serovar C. The other 23 isolates were nontypable by the agglutination test, but 21 of them could be serotyped by the HI method--six as serovar A, two as serovar B, and 13 as serovar C. Nine isolates required treatment of the bacterial cells with hyaluronidase for the expression of hemagglutination (HA) activity. Two isolates did not have HA activity despite hyaluronidase treatment and so could not be serotyped by the HI test.  相似文献   

5.
Chuzan virus agglutinated erythrocytes of several species of animals including bovine. The hemagglutinating (HA) activity against bovine erythrocytes was dependent on NaCl molarity and was expressed best at 0.6 M, but it was independent of pH and temperature. Three strains of Chuzan virus isolated from 2 cows and a pool of culicoides midges had indistinguishable HA antigenicity. All cattle infected with the virus developed high titers of hemagglutination inhibiting (HI) antibody which changed in parallel with neutralizing (NT) antibody titers. Correlation between HI and NT antibodies was very high and the antibodies persisted for one year or more. Therefore it was concluded that the HI test is applicable for survey of Chuzan virus infection among cattle in place of the NT test.  相似文献   

6.
Four field isolates (S4, S10, S15, and S17) of Haemophilus paragallinarum were recovered from chickens affected with infectious coryza in widely separated regions of Japan. Their hemagglutinating (HA) activity and immunological properties were compared with those of strain 221 of serovar A/1 and strains Modesto and S1 of serovar C/2. When treated with potassium thiocyanate or hyaluronidase, all the isolates showed HA activity against formaldehyde-fixed chicken erythrocytes but not against fresh chicken erythrocytes. In the hemagglutination-inhibition (HI) test, the isolates cross-reacted with strains Modesto and S1 but not with strain 221. The immunological properties of these isolates, as determined by cross-protection tests, were similar to those of strain S1 and, to a lesser degree, strain Modesto, but not to strain 221. Our results indicated that the four field isolates belong to serovar C/2 and that the HI test is a suitable method for serotyping H. paragallinarum.  相似文献   

7.
Cells infected with bovine coronavirus (BCV) were solubilized with Triton X-100 to yield a cell lysate (CL) antigen having high hemagglutinating (HA) titers. The antigen gave high HA titers using rat erythrocytes, suggesting that it contained large amounts of hemagglutinin esterase (HE) antigen. The CL antigen, combined with an oil adjuvant, was tested for protective and antibody-inducing activities in cattle. Four groups (2 cattle/group) of cattle were inoculated with CL antigen having HA titers of 16 000, 4000, 1000, and 250. Another group served as untreated controls. Two intramuscular inoculations were given at an interval of 3 wk. The animals were challenged with virus 1 wk after the second inoculation. The groups immunized with the CL antigen having an HA titer of 4000 or 16 000 produced hemagglutination inhibition (HI) antibody titers of > 320 and serum neutralizing (SN) antibody titers of > 1280. These groups of animals showed no clinical abnormalities after challenge. In the groups immunized with CL antigen at an HA titer of 1000 or 250, HI antibody titers were 40 to 160 and SN titers were 80 to 640. The cattle with HI antibody titers of > or = 160 and the SN titers of > or = 640 showed no clinical signs, but the cattle with the HI antibody titer < 80 and the SN antibody titer < 160 developed watery diarrhea and fever after challenge. These results indicate that CL antigen with high HA titer induces antibody production in cattle that provides effective protection against winter dysentery.  相似文献   

8.
Concentrated cell culture fluids of African horse sickness virus were shown to agglutinate erythrocytes from cattle, horses, sheep, goats, guinea pigs, rabbits, and poultry at 4°C, room temperature, and 37°C. The titres obtained were dependent on pH and NaCl molarity of the diluent, optimal titres being obtained at pH 7.5 and 0.6 M NaCl. The HA inhibiting antibodies to two AHS viruses were proven to be type specific.  相似文献   

9.
Rotavirus VP8*, the N-terminal trypsin cleavage product of VP4, has been shown to bind to MA-104 cells and human O type erythrocytes. To examine whether bacterially expressed VP8* binds to cellular components of MA-104 cells, the VP8* (aa 1-247) was expressed in E. coli and radiolabelled with 35S-methionine. The radiolabelled rVP8* was immunoprecipitated with antiserum to bovine rotavirus C486 (BRV). The rVP8* was found to bind to MA-104 cells and its binding was competed by BRV. To study the interaction between VP8* and receptors of erythrocytes, hemagglutination (HA) and hemagglutination inhibition (HI) assays were carried out using solubilized rVP8*. rVP8* showed HA which could be inhibited by antiserum to BRV. This interaction was also inhibited by gangliosides, demonstrating a sialic acid dependent interaction. To study the contribution of the C-terminal region of VP8* to HA, a number of approaches were used. First, a peptide spanning aa 230-247 was synthesized and antisera was raised against the peptide to see whether it could inhibit HA of rVP8*. Second, a truncated form of VP8* (tVP8*: aa 1-229) was expressed to examine its hemagglutinating activity. Third, the dimerization of rVP8* and tVP8* was compared by Western-blotting following electrophoresis using native SDS-PAGE. The results indicated that antibody to aa 230-247 inhibits hemagglutination by preventing dimerization of VP8* which in turn allows the molecule to cause HA. To characterize the interaction between the HA domain and sialic acid receptors, erythrocytes were treated with sialidases of different specificities. Arthrobacter ureafaciens, Clostridium perfringens and alpha 2-8 linkage-specific neuraminidase destroyed the ability of sialic acid of erythrocytes to interact with rVP8*, indicating that bovine rotavirus C486 binding requires an alpha 2-8 linkage but acetylation of the sialic acid is not necessary.  相似文献   

10.
The serological response of chickens either vaccinated or artificially infected with Haemophilus paragallinarum (Hpg) serovar A or C was investigated using both a specific hemagglutinin (HA) antigen and a common HA antigen. With Hpg serovar A, both vaccinated and artificially infected chickens produced hemagglutination-inhibition (HI) antibodies to Hpg serovar-specific and Hpg common HA antigens. Most chickens vaccinated with Hpg serovar C had detectable HI antibodies to both types of HA antigen by 3 weeks postvaccination, after which titers gradually declined. In contrast, most chickens artificially infected with serovar C produced HI antibodies to only the common HA antigen; very few of these chickens produced HI antibodies to the serovar-specific HA antigen.  相似文献   

11.
Basic variables of the haemagglutination inhibition (HI) test for porcine parvovirus antibody were investigated. Nonspecific serum inhibitors were satisfactorily removed without loss of specific antibody when undiluted serum was adsorbed with 25 percent kaolin in borate saline at pH 9.0. Natural haemagglutinins in test serums could be completely removed using 0.1 ml of packed erythrocytes to 0.6 ml of kaolin treated serums. Adsorption of prediluted serum resulted in a depression of specific antibody titres. Highest HI titres were obtained using guinea pig erythrocytes, following incubation of virus-serum mixtures for 18 hours at 4 degrees C, 3 hours at 25 degrees C or 2 hours at 37 degrees C. Micro- and macro-tests gave comparable HI titres.  相似文献   

12.
An improved hemagglutination test for study of canine parvovirus   总被引：2，自引：0，他引：2  
Optimal conditions for hemagglutination (HA) by canine parvovirus (CPV) strains were investigated using several buffers. Porcine erythrocytes often agglutinated spontaneously in phosphate-buffered salt solution, isotonic saline solution or barbitone-complement-fixation buffer. Results were reproducible when borate-buffered saline (BBS) was used as the diluent for antigen, and "virus adjusting diluent" (VAD), containing 0.15 M NaCl and 0.3 M phosphate was used as the diluent for erythrocytes. Highest HA titers were obtained at pH 6.0 using BBS and VAD. Specific HA with CPV was observed not only at 4 degrees C but at 37 degrees C, and erythrocytes from horse, shrew mouse, hamster, cat, sheep and dog, as well as pig and African green monkey were agglutinated by CPV using the improved method.  相似文献   

13.
Abstract

Herbage intake (HI), milk production and sward utilization of Norwegian Red Cattle dairy cows in mid-lactation, rotationally grazing grass/white clover swards at low, medium and high allowances (HA), were examined in three experiments (I, II and III). The daily target allowances per cow were 18 and 36 kg DM in Experiment I and 12, 18, and 24 kg DM in Experiments II and III. The cows were grazing in groups of seven (Experiments II and III) to ten (I) individuals. The proportions of white clover in the swards averaged 12%, 40% and 46% in Experiments I, II and III, respectively. In addition to pasture, the cows were fed concentrate mixtures in varying amounts (0–6.8 kg) with the highest amounts offered to the highest yielding cows. HI was estimated using the n-alkane technique. No effect of HA on HI was obtained in Experiment I. In Experiment II, and for II and III combined, there was a significant positive effect of HA on HI. The average increase in HI was 0.24 kg DM per extra kg DM on offer. The utilization of the sward (measured at 3 cm above ground level) decreased from 72% at the lowest HA to 51% at the highest HA in Experiment II and III. HA did not affect milk yield or milk composition significantly (P>0.05).  相似文献   

14.
Sheep complement (C) is haemolytic for sheep erythrocytes sensitized with rabbit antibody (sheep E-rabbit A) provided serum is used as soon as possible after collection. If left at 4 °C to separate from the clot, serum C activity for sheep E-rabbit A is markedly reduced. Heparinized plasma retains its haemolytic titre for at least 24 h at 4 °C. Plasma from Mg2+-ethyleneglycoltetraacetic acid (EGTA) blood is non-haemolytic, but addition of Ca2+ partially restores the titre. A high concentration of rabbit A is necessary to sensitize sheep E.Sheep C is haemolytic for human erythrocytes sensitized with sheep antibody (human E-sheep A) in the presence of Mg2+-EGTA. This C activity is stable at 4 °C for 24 h in serum, Mg2+-EGTA plasma and heparinized plasma. Haemolytic activity of serum heated at 50 °C for 30 min was restored by a factor B containing CM-cellulose fraction of foetal lamb serum in the presence of Mg2+-EGTA for human E-sheep A but not sheep E-rabbit A.These findings show that sheep C haemolysis of sheep E-rabbit A requires a Ca2+-Mg2+-dependent pathway that is labile in vitro for 24 h at 4 °C.  相似文献   

15.
A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 213 per 25 µL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4℃. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays.  相似文献   

16.
Psittacine beak and feather disease (PBFD) is a common viral disease of wild and captive psittacine birds characterized by symmetric feather loss and beak deformities. The causative agent, beak and feather disease virus (BFDV), is a small, circular single-stranded DNA virus that belongs to the genus Circovirus. BFDV can be detected by PCR or the use of haemagglutination (HA) and haemagglutination inhibition (HI) assays that detect antigen and antibodies respectively. Erythrocytes from a limited number of psittacine species of Australian origin can be used in these tests. In South Africa, the high cost of these birds makes them difficult to obtain for experimental purposes. Investigation into the use of erythrocytes from African Grey parrots and Brown-headed parrots yielded positive results showing the haemagglutinating activity of their erythrocytes with purified BFDV obtained from confirmed clinical cases of the disease. The HA activity was further confirmed by the demonstration of HI using BFDV antiserum from three different African Grey parrots previously exposed to the virus and not showing clinical signs of the disease.  相似文献   

17.
Two serovar-specific monoclonal antibodies (MAbs) to Haemophilus paragallinarum serovars A/1 and C/2 strains, respectively, were developed and characterized by hemagglutination-inhibition (HI) and dot-blotting tests using representative H. paragallinarum serovars A/1, B, and C/2 strains. In both the HI and dot-blotting tests, one MAb (E5C12D10), raised against strain 221, serovar A/1, reacted only with serovar A/1 strains, while the other MAb (F2E6), raised against strain S1 of serovar C/2, reacted with only serovar C/2 strains examined. In both tests, the two MAbs did not react with two serovar B strains. These results indicated that the two MAbs recognize serovar-specific hemagglutinating (HA) antigens of H. paragallinarum serovars A/1 and C/2 strains, respectively, and that a dot-blotting test using these MAbs is a practical alternative to the HI test for serotyping H. paragallinarum. Strains 0222 and Spross of serovar B, which did not react with these two MAbs, were found to possess serovar-specific HA antigen in cross-HI tests.  相似文献   

18.
Eleven Salmonella strains known to produce enterotoxin under aerobic culture conditions in deferrated (DF) medium at 37°C were shown to produce enterotoxin with and without aeration at 22, 28, 37 and 42°C. Heat-labile enterotoxin was generally produced with growth temperatures up to 37°C irrespective of aeration. Heat-stable enterotoxin was produced up to 42°C, mainly aerobically, as indicated by infant mouse assay (IMA), by six of the eleven strains tested. Nine strains produced heat-stable rapid permeability factor (RPF) in rabbit skin.Cholera anti-toxin neutralized reactivities of Salmonella heat-labile enterotoxin in four different biological assays. Mixed gangliosides also neutralized this activity in the cell—test systems.With guinea-pig erythrocytes, all strains underwent mannose-resistant hemagglutination (MRHA) irrespective of growth temperatures, i.e. 22 and 37°C or medium, i.e., DF, tryptose soy broth (TSB) and colonization factor antigen (CFA) agar. At both growth temperatures, CFA agar-grown cells of each strain caused MRHA of bovine erythrocytes. Excepting three Salmonella typhimurium strains, DF broth-grown cells gave MRHA of bovine, chicken and human group A erythrocytes, CFA agar-grown cells caused MRHA of chicken and human blood, whereas TSB-grown cells caused few MRHA reactions.Salmonellae producing both heat-stable, (ST) and heat-labile, (LT) enterotoxins adsorbed to Phenyl Sepharose whereas salmonellae that produced only LT enterotoxin did not.The presence of MRHA adhesions did not correlate with cell-surface hydrophobicity. However, mannose-resistant hemagglutinins may occur more commonly among salmonellae than has been previously recognized.  相似文献   

19.
I–2 is an avirulent strain of Newcastle disease virus. During establishment of the I-2 strain master vaccine seed, a series of selection procedures was carried out at 56°C in order to enhance heat resistance. This master seed is used to produce a working seed, which is then employed to produce the vaccine. These two passages are done without further heat selection; however, it is not known how rapidly and to what extent thermostable variants would be lost during further passage. The study was therefore conducted to determine the effect of passage on thermostability of strain I-2. The virus was serially passaged and at various passage levels samples were subjected to heat treatment at 56°C for 120 min. The inactivation rates for infectivity and haemagglutinin (HA) titres were assayed by use of chicken embryonated eggs and HA test, respectively. Thermostability of HA and infectivity of I-2 virus were reduced after 10 and 5 passages, respectively, without heat selection at 56°C. These results suggest that 5 more passages could be carried out between the working seed and vaccine levels without excessive loss of thermostability. This would result in increased vaccine production from a single batch of a working seed.  相似文献   

20.
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