Transmission of protease genes into a protease-deficient mutant of Aeromonas salmonicida in river sediments

Abstract. The transformation of Aeromonas salmonicida with DNA fragments from bacterial cell-free sonicates was investigated with intraspecific, interspecific band intergeneric fish pathogenic bacteria including Aeromonas salmonicida, Aeromonas hydrophila, Pseiidomonas fluorescens and Vibrio anguillarum strains as donor bacteria. A phenotypic marker for transformation was extracellular protease production since a protease-deficient mutant NTG-1 induced from pathogenic A. salmonicida strain A-7301 by mutagenesis was used as a recipient. This mutant was non-pathogenic to rainbow trout. The mutant was incubated with each sonicate at 20°C for 20 days with a nutrient-poor medium containing a trace (5 μg/ml each) of both humic acid and tryptone in the presence of clean river sand (100 g/100 ml medium) corresponding with an environment of rivers. During the incubation, the survival of mutant NTG-1 cells was observed and protease positive NTG-1 cells were isolated from each culture. The protease production of the isolates was due to the transmission of protease genes of the donor strains. The activity of proteases produced by the transformants extra-cellularly was determined. These transformants induced with the sonicates of the parent strain, intraspecific strain and with the sonicates of the interspecific A. hydrophila strain were pathogenic to rainbow trout, whereas the transformants derived with the sonicates of the intergeneric strains P. fluorescens and V. anguiUarum showed non-pathogenicity, although all the donor strains, with the exception of the P. fluorescens strain, were pathogenic. These findings are interesting since they demonstrate that trausformation in A. salmonicida occurs with considerable ease even intergenencally and interspecifically, as well as intraspecifically in river environments, and that there is a large difference in the lethal toxicity of extracellular protease produced by these bacteria.     

Genetic Effects for Response to Live Edwardsiella ictaluri, Killed E. ictaluri, and Stress in Juveniles from All Crosses Among USDA 103, USDA 102, and Norris Channel Catfish Ictalurus punctatus Strains

Juveniles from all possible crosses among USDA 102. USDA 103, and Norris channel catfish Ictalurus punctatus strains were compared for: 1) survival and mix-Edwardsiella ictaluri antibody after exposure to live E. ictaluri bacterium (isolate 597-458); 2) antibody level after injection with formalin-killed E. ictaluri (597-458); and 3) pre-stress. post-stress, and stress-recovery serum Cortisol levels. Purebred and crossbred USDA 102 strain fish had higher survival (mean of five genetic groups = 87%) and lower anti- E.ictaluri antibody (mean optical density (OD) of five genetic groups = 0.167) 30 d after live E. ictaluri challenge than purebred Norris and USDA 103 strains and their crosses (means of four genetic groups = 60% survival and 0.210 OD antibody level). Significant general combining ability, line effects, and heterosis indicated that the USDA 102 strain contributed additive and dominance genetic effects for increased survival and lower antibody level after live E. ictaluri challenge. Antibody response to formalin-killed, intra-peritoneally injected E. ictaluri was not different among genetic groups (overall mean = 0.198 OD). Serum Cortisol was measured prior to (pre-stress), immediately after (post-stress), and 2 h after (stress-recovery) a standard stressor. Serum Cortisol level was highest in post-stress fish (35.8 ng/mL), intermediate in stress-recovery fish (10.9 ng/mL), and lowest in pre-stress fish (6.5 ng/mL), but was not different among genetic groups within a stress time period. Results indicate diat differences exist among genetic groups of channel catfish for survival and antibody production after live E. ictaluri challenge, but these differences were not related to antibody response to killed E. ictaluri or serum Cortisol levels.     

Cross‐neutralization studies with salmonid alphavirus subtype 1–6 strains: results with sera from experimental studies and natural infections

The serological reactivity between strains of each of the six currently genetically defined subtypes of salmonid alphavirus (SAV) was examined by comparison of homologous and heterologous virus neutralization titres on sera from experimentally infected fish. With the exception of the level of SAV subtype 6 neutralization by heterologous sera, good cross‐neutralization was detected between all subtypes, albeit with variation in geometric mean titres when each subtype‐specific serum set was tested against the panel of virus subtypes. A similar pattern was evident with field sera, except that heterologous neutralization of the SAV6 strain was more evident. In only 23% of available pairwise comparisons was the homologous titre recorded with an experimentally derived serum fourfold or greater than the heterologous titre, and in only two instances was this difference demonstrated in both directions. No virus strains consistently met the old serology‐based criteria (Sub‐committee on Inter‐relationships Among Catalogued Alphaviruses) to be considered separate subtypes within an alphavirus species. Only when testing with an SAV subtype‐2‐specific monoclonal antibody was a major difference between homologous and heterologous neutralization capacity evident. These results provide new direct or indirect information in terms of SAV classification, vaccine efficacy and the selection and validation of reagents for serological and immunological diagnostic purposes.     

银鲫对嗜水气单胞菌灭活菌苗的免疫应答研究

以绵羊红细胞为载体,建立了检测银鲫血清抗体的间接血球凝集试验。用该方法研究了银鲫对嗜水气单胞菌灭活菌苗的免疫应答一般规律。研究结果表明,疫苗免疫组在免疫７天后可以测到血凝抗体,２１天达到高峰值４０９６,然后开始下降,３５天时抗体滴度降为１６。加弗氏不完全佐剂疫苗免疫组亦在７天时可以测到血凝抗体,２１天达到１０２４,３５天时为２０４８,抗体维持在较高的水平。对鱼体免疫后的保护力进行测定,结果表明,两个免疫组分别在７天左右和１４天左右开始产生保护力。免疫保护力在鱼体免疫初期随着抗体滴度的增加而加强,随后在一段时间内保持在较强的水平,并不随抗体滴度的下降而减弱。浸泡免疫试验的结果亦表明,银鲫可以通过浸泡免疫获得免疫保护力。     

Specific immunoglobulins in serum from Atlantic salmon, Salmo salar L., immunized with Vibrio salmonicida and infectious pancreatic necrosis virus

Abstract. Atlantic salmon, Salmo salar L., responded to intraperitoneal injection of formalin killed Vibrio salmonicida or live infectious pancreatic necrosis virus ( ipnv ) by producing specific antibodies. The antibody titre varied significantly within the group tested. Western blot analysis demonstrated that high-titre antisera recognized two major bacterial antigens with molecular weights of 12–15 kD and 22–27 kD. In addition, a few narrow bands with higher molecular weights were observed. An antiserum raised against IPNV recognised two major antigens corresponding to the structural proteins of the virus. E lisa and Western blot analysis showed that the immune serum raised against Vibrio salmonicida reacted slightly with Vibrio anguillarum , whereas no reaction to Yersinia ruckeri or Aeromonas salmonicida was detected. Indirect elisa and an elisa competition assay revealed that the immune serum raised against the N1 serotype was specific for this serotype of ipnv . The results demonstrate that Atlantic salmon has a humoral immune system capable of producing antibodies which discriminate between related bacterial antigens and between different serotypes of a virus.     

一株产低温碱性蛋白酶嗜冷海洋细菌YS-9412-130的分离和培养条件研究

自海水贝类中取样，经分离培养基和酪蛋白培养基复合培养，用检测蛋白酶产生水解圈和Folin-酚碱性蛋白酶活性测定相结合的方法从1000多份样品中初步筛到了产碱性蛋白酶活力高、性能优良的菌株YS－9412－130。对其初步研究结果表明，该菌只能利用有机氮源生长；在接近自然海水盐度、温度20℃、pH在7.0-9.0条件下，菌体生长和产酶较好。     

Immune responses of channel catfish, Ictalurus punctatus (Rafinesque), after oral or intraperitoneal vaccination with particulate or soluble Edwardsiella ictaluri antigen

Abstract. Groups of channel catfish, Ictalurus punctatus (Rafinesque). were administered Edwardsiella ictaluri twice in the form of whole outer membrane proteins (OMP) or heat-inactivated whole bacteria (IWB) orally or IWB intraperitoneally. Antibody titres and lysozyme concentrations were determined in serum, mucus, gut contents and gut washings taken 7, 14, 21 and 28 days after the second antigen administration. Bacterial killing by anterior kidney neutrophils was determined 7, 14 and 21 days after the second antigen administration. Enhanced killing of tumour targets by nonspecific cytotoxic cells (NCC) was determined 7 days after the second antigen administration. Serum antibody titres of all treatment groups were significantly increased above those of the control group throughout all sampling periods. Fish receiving oral administration of OMP or IWB exhibited maximum serum antibody titres on day 21 or 28. Antibody titres were also detected in mucus, gut washings and gut contents, but did not reach the level of those in the serum. Bacterial killing was significantly increased only on day 7, and could not be correlated to antibody titre or lysozyme concentration. Bacterial killing was found to be the result of a heat-labile serum factor. NCC activity of fish vaccinated with IWB orally was significantly higher than that of fish vaccinated with OMP orally or controls. Although intraperitoneal vaccination consistently produces higher titre antisera, the results of this study support the idea that oral vaccination can induce antibody systhesis.     

Dietary levamisole modulates the immune response and disease resistance of Asian catfish Clarias batrachus (Linnaeus)

In order to determine the immunomodulatory effect of dietary levamisole in Asian catfish (Clarias batrachus), fish were fed four different diets for 10 days: a formulated diet as control and the same diet supplemented with 50, 150 or 450 mg levamisole kg^?1 feed. The serum bacterial agglutination titre against Aeromonas hydrophila as a measure of specific immunity, serum haemagglutination titre, natural haemolytic complement activity (ACH₅₀), myeloperoxidase and lysozyme activities, total protein level and oxidative radical production by neutrophils as a measure of non‐specific immunity as well as disease resistance against A. hydrophila challenge to separate vaccinated and non‐vaccinated groups were evaluated at 0, 1, 2 and 3 weeks after last administration of levamisole. Levamisole supplement at the lowest level (50 mg kg^?1) significantly enhanced oxidative radical production and serum myeloperoxidase (MPO) content immediately after 10 days of feeding, which reached peak values after 3 and 2 weeks of feeding respectively. Haemolytic complement and haemagglutination titre were significantly enhanced after 3 and 1 weeks respectively. Haemolytic complement activity and MPO activities were significantly raised to 150 mg kg^?1 after 3 and 2 weeks, respectively. At the highest level of levamisole feeding (450 mg kg^?1) significant decreases in superoxide production and complement activity were measured immediately after levamisole feeding, which returned to the normal level after 1 week post‐ feeding. Fish were challenged with a virulent strain of A. hydrophila at 0, 1, 2 and 3 weeks after levamisole feeding, and the cumulative per cent survival was recorded over 10 days. Feeding levamisole at 50, 150 or 450 mg kg^?1 increased per cent survival in vaccinated fish immediately after levamisole feeding, and survival was significantly higher at 450 mg kg^?1. There was no difference in mortality patterns in non‐vaccinated fish. The results support the use of levamisole at 50 mg kg^?1 feed for 10 days as an immunostimulant in Asian catfish farming.     

Infectious pancreatic necrosis virus of salmonids: biological and antigenic features of a pathogenic strain and of a non-pathogenic variant selected in RTG-2 cells

Abstract. A non-pathogenic cell culture adapted variant was obtained from a normally pathogenic strain of IPN virus (Sp type) after several passages in RTG-2 cells. This cell culture modified (CCA) strain was compared with the original wild (W) strain in various tests. Cross neutralization tests showed no obvious antigenic difference between the two. However the CCA strain was neutralized by a 1:5000 dilution of normal trout serum whereas the W strain was not. In RTG-2 cells, CCA strain gave both large and small plaques, whereas the W strain gave only small ones. Both virus strains were heat sensitive and labile to cyclic freezing and thawing. The CCA virus was more stable in storage at 4°C under different pH conditions and its growth in RTG-2 cells was more rapid. The rt (supraoptimal temperature at which viral yield is depressed by 90%) appeared to be 19-20°C for the CCA strain and 18-19°C for the W strain. Pre-treatment of RTG-2 cells with ultraviolet inactivated CCA virus could inhibit growth of W virus, but had no effect on replication of homologous virus.     

Effects of dietary pyridoxine on disease resistance,immune responses and intestinal microflora in juvenile Jian carp (Cyprinus carpio var. Jian)

This experiment was conducted to evaluate the effects of dietary pyridoxine on disease resistance, immune responses and intestinal microflora of fish. A total of 1050 Jian carp (11.71 ± 0.05 g) were randomly distributed into seven groups, feeding diets containing graded levels of pyridoxine (0.2, 1.7, 3.2, 5.0, 6.3, 8.6 and 12.4 mg kg^?1 diet). After 80 days of feeding, a challenge trial was conducted by injection of Aeromonas hydrophila for 17 days. Results indicated that with increasing dietary pyridoxine concentration up to 5.0 mg kg^?1 diet, survival rate after challenge with A.hydrophila and phagocytic activity of leukocyte were improved (P < 0.05), and plateaued thereafter (P > 0.05). Red blood cell and white blood cell counts were lowest when fed the diet containing 1.7 mg pyridoxine kg^?1 diet. Haemagglutination titre, lysozyme activity, acid phosphatase activity, total iron‐binding capacity, antibody titre and immunoglobulin M content followed the similar pattern to that observed with survival rate. Aeromonas hydrophila, Escherichia coli and Lactobacillus counts in intestine were not affected by dietary pyridoxine concentration (P > 0.05). These results suggested that pyridoxine could enhance immune response of fish.     

Influence of high dietary α-tocopherol intakes on specific immune response, nonspecific resistance factors and disease resistance of healthy and aflatoxin B1-induced immunocompromised Indian major carp, Labeo rohita (Hamilton)

The effect of aflatoxin treatment and/or feeding of a high level of α‐tocopherol on immune response and disease resistance was investigated in Indian major carp, Labeo rohita. Group A served as a healthy control, group B was treated with aflatoxin, group C was fed a high level of α‐tocopherol whereas group D was exposed both to aflatoxin and a high level of dietary α‐tocopherol for 60 days. Aflatoxin B₁ (AFB₁) was injected once intraperitoneally into fish on the first day of the experiment (groups B & D). High levels of DL‐α‐tocopherol (1000 mg kg^–1 feed) were provided to healthy as well as AFB₁‐treated immunocompromised fish for 60 days (groups C & D). At the end of the experiment blood samples were assayed for changes in nonspecific immunity and humoral protein levels. Disease resistance against two common bacterial pathogens viz., Aeromonas hydrophila and Edwardsiella tarda were evaluated in all groups. Significant (P < 0.05) suppression of specific immunity as measured through haemagglutination (HA) titre against sheep red blood cells (SRBCs) as well as bacterial (formalin‐killed E. tarda) agglutination titre; nonspecific resistance factors viz., globulin level, serum bactericidal and lysozyme activities, neutrophil activities, and disease resistance against two bacterial pathogens only in aflatoxin‐treated fish with respect to the control group, clearly indicated the immunosuppressive nature of aflatoxin. Feeding of a high level of α‐tocopherol to AFB₁‐treated immunocompromised fish significantly (P < 0.05) raised specific immunity, nonspecific resistance factors and disease resistance capacity when compared with aflatoxin‐exposed fish. Disease resistance and enhancement of immune status through feeding of high levels of α‐tocopherol to healthy as well as AFB₁‐treated immunocompromised fish confirmed the potential of α‐tocopherol in carp feed for prevention of disease and for combating natural/environmental immunosuppressants.     

Use of an ELISA-based assay for the detection of antibody-secreting cells in channel catfish, Ictalurus punctatus (Rafinesque)

Abstract. An ELISA-bascd plaque assay for the detection and quantification of antibody-secreting cells has been adapted for use in fish. The assay involves incubating catfish lymphocytes in 24-well plates previously coated with the antigen of interest. Cells producing antibody to the antigen leave an immunological fingerprint of bound antibody which is detected through the use of an ELISA technique to yield a colored plaque (Elisaplaque). Specificity of the assay was established by demonstrating that cells taken from fish vaccinated with an antigen exhibit the greatest response on plates coated with the given antigen. A strong positive correlation was also demonstrated between the number of Elisaplaques generated and serum agglutination titre. Using the ELISA plaque assay, it was found that antibody-secreting lymphocytes located at a different density interface and behaved differently from other lymphocyte populations when separated through discontinuous Percoll gradient centrifugation. Among the haematopoietic organs examined, the head kidney appeared to produce more antibody-secreting cells per million lymphocytes than did spleen or peripheral blood lymphocytes.     

In vitro markers for virulence in Yersinia ruckeri

In this study, different traits that have been associated with bacterial virulence were studied in Yersinia ruckeri. Two isolates that had been shown to cause disease and mortality in experimentally infected rainbow trout were compared with five avirulent isolates. Both virulent isolates showed high adhesion to gill and intestinal mucus of rainbow trout, whereas the majority of non‐virulent strains demonstrated significantly lower adhesion. A decrease in adherence capability following bacterial treatment with sodium metaperiodate and proteolytic enzymes suggested the involvement of carbohydrates and proteins. All strains were able to adhere to and invade chinook salmon embryo cell line (CHSE‐214), fathead minnow epithelial cell line (FHM) and rainbow trout liver cell line (R1). One non‐virulent strain was highly adhesive and invasive in the three cell lines, whereas the virulent strains showed moderate adhesive and invasive capacity. The internalization of several isolates was inhibited by colchicine and cytochalasin‐D, suggesting that microtubules and microfilaments play a role. For all strains, intracellular survival assays showed a decrease of viable bacteria in the cells 6 h after inoculation, suggesting that Y. ruckeri is not able to multiply or survive inside cultured cells. Analysis of the susceptibility to the bactericidal effect of rainbow trout serum demonstrated that virulent Y. ruckeri strains were serum resistant, whereas non‐virulent strains were generally serum sensitive.     

Survival and humoral antibody response of Atlantic salmon, Salmo salar L., vaccinated against Aeromonas salmonicida ssp. achromogenes

Atlantic salmon were vaccinated against Aeromonas salmonicida ssp. achromogenes (Asa) by injection with three vaccines developed in our laboratory and an autogenous bacterin (IcelandBiojec.OO, IBOO) produced by a commercial vaccine producer. The humoral antibody responses to bacterial antigens were monitored by ELISA and Western blotting. The fish were challenged by infection with Asa 6 and 12 weeks post-vaccination. Protection was induced in all groups of vaccinated fish. The protection achieved was time-dependent. The autogenous bacterin, IBOO, induced a protective immune response later than our experimental vaccines. All the vaccines tested induced specific antibody response that increased between 6 and 12 weeks after vaccination. The antibody response was mainly directed against the A-layer protein, but antibodies to other bacterial components were also detected. Significant correlation was obtained between the antibody titre to extracellular Asa antigens, induced by the different vaccine preparations, and survival of vaccinated fish challenged by a virulent Asa strain. Furthermore, the detection of antibodies directed against an extracellular toxic metallo-caseinase, AsaP1, in fish sera correlated with protection.     

Vaccination of rainbow trout, Oncorhynchus mykiss (Walbaum), against cryptobiosis: efficacy of the vaccine in fresh and sea water

Adult rainbow trout, Oncorhynchus mykiss (Walbaum), maintained in either fresh or sea water were vaccinated with a live Cryptobia salmositica vaccine. All vaccinated fish were protected 4 weeks later against the cryptobiosis, while unvaccinated rainbow trout developed the disease (e.g. high parasitaemia and severe anaemia) after challenge with virulent C. salmositica . There was also no disease in vaccinated fish when they were transferred from fresh to sea water immediately after vaccination. Complement fixing antibodies (CFAbs) were detected in vaccinated fish and the CFAbs lysed parasites under in vitro conditions. The antibody titres increased rapidly at one week post-challenge in vaccinated fish in fresh water and vaccinated fish transferred from fresh water to sea water after vaccination. However, the production of CFAbs was delayed by one week in vaccinated fish in sea water and the antibody titre was significantly lower than that in fish maintained in fresh water.     

Immune response, growth and survival of Labeo rohita fingerlings fed with levamisole supplemented diets for longer duration

The study was to determine the effect of long-term administration of different dosages of levamisole on growth, immune response and disease resistance against Aeromonas hydrophila & Edwardsiella tarda in Labeo rohita fingerlings. Fish were fed with four different dosages of levamisole (0, 125, 250 and 500 mg kg⁻¹ diet) for 56 days. Different serum biochemical and haematological parameters such as serum total protein content, albumin content, globulin content, albumin/globulin ratio, glucose content, leucocytes count; cellular immune parameters including superoxide anion production, phagocytic activities, lymphokine production index; humoural immune parameters including lysozyme, complement and serum bactericidal activities were evaluated after 14 days interval. After 56 days, fish were divided into two subgroups under each treatment group for challenge with pathogens A. hydrophila and E. tarda . The cumulative mortality (%) and agglutinating antibody titre was recorded on 28th day postchallenge. WBC count, phagocytic ratio, lymphokine production index, lysozyme activity and serum bactericidal activity were increased upon administration of levamisole dosages for long term. However, the growth performance and survival against pathogens was not significantly changed over 56 days administration of levamisole. But incorporation of moderate dosage of levamisole for 42 days results better immune response without effect on growth and survival of L. rohita fingerlings.     

Characterization of a monoclonal antibody against the 47- kDa antigen of Cryptobia salmositica Katz and its use in an antigen-capture enzyme-linked immunosorbent assay for detection of parasite antigen in infected rainbow trout, Oncorhynchus mykiss (Walbaum)

A monoclonal antibody (designated MAb-007) was produced against the pathogenic haemoflagellate Cryptobia salmositica Katz. This IgG3 antibody recognized the 47-kDa antigenic polypeptide of C. salmositica (SDS-PAGE and Western immuno-blotting). The antibody did not agglutinate live parasites, and there was no change in the staining intensity of the 47-kDa band on Western immunoblots after immunoabsorption of MAb-007 with live intact parasites. The 47-kDa antigen recognized by MAb-007 was localized in the cytoplasm of the parasite (immunogold labelling and electron microscopy). The monoclonal antibody cross- reacted with the 47-kDa polypeptides of C. bullocki Srrout and C. catostomi Bower & Woo. It was used in an antigen-capture ELISA for the detection of parasite antigen in the plasma of rainbow trout inoculated with the parasite, or with an attenuated vaccine strain of C. salmositica. All pre-infection plasma were negative while all infected fish with detectable parasitaemias were positive for antigen at 1–9 weeks after infection. Parasite antigen was even detected in vaccinated fish that were negative for parasites using the wet mount microscopic technique. The antigen-capture ELISA detected C, salmositica antigen in whole cell lysate preparations at concentrations as low as 0.5 μg ml^-1. Fifty microlitres of fish plasma was required in the antigen-capture ELISA, and the use of a plate reader and 96-well plates facilitated rapid analysis of a large number of plasma samples. The sensitivity of the assay makes it a potentially useful tool for detection of Cryptobia infections.     

Comparative analysis of the phenotypic characteristics of high- and low-virulent strains of Edwardsiella tarda

Edwardsiella tarda is a causative agent of edwardsiellosis in freshwater and marine fish. Extracellular enzymic, haemolytic, hydrophobic and serum resistance activities, haemagglutination, autoagglutination and siderophores of high‐ and low‐ virulent E. tarda strains were examined. The results revealed different haemagglutination, autoagglutination, haemolytic, hydrophobic and serum resistance activities in different strains. Analysis of extracellular proteins (ECPs) and outer membrane proteins (OMPs) demonstrated several major, low molecular weight, virulent‐strain‐specific proteins, which could be virulence‐related. Based on the database search with MALDI‐TOF MS data, the closest homologies of the three protein bands Ed1, Ed2 and Ed3 were phosphotransferase enzyme family protein, nitrite reductase [NAD(P)H], large subunit and ATP‐dependent Lon protease, respectively. A comparison of pathogenicity of purified lipopolysaccharide (LPS) and lipid A from virulent and avirulent strains demonstrated that LPS was one of the virulence factors of the E. tarda isolates, and lipid A was a biologically active determinant of LPS.     

蟹源致病性拟态弧菌的粘附及侵袭特性

病原菌对机体的致病作用是由其产生的各种毒力因子共同作用的结果,其中病原菌对组织细胞或粘膜的表面粘附是造成机体感染的首要条件。病原菌的粘附因子主要包括菌毛粘附素和其它非菌毛粘附素(如鞭毛、外膜蛋白和血凝素等),其中以菌毛介导的病原菌对组织细胞的粘附是细菌在体内定居、增殖释放毒力因子发挥致病作用的关键。为了揭示拟态弧菌HX 4的致病机理,以经典粘附模式细胞HEp 2细胞作为体外细胞模型,探讨蟹源致病性拟态弧菌HX 4株的粘附特性以及受体物质和抗全菌抗体对细菌粘附作用的影响,同时采用庆大霉素清洗裂解培养法测定该菌对HEp 2细胞的侵袭力。结果显示,HX 4菌株能粘附HEp 2细胞,对HEp 2细胞具有侵袭力。细菌对HEp 2细胞的粘附方式为集聚性粘附,最佳粘附时间为1h,甘露糖和抗体能显著抑制该菌的粘附,表明HEp 2细胞上含有甘露糖样受体。该菌的粘附素除了主要是菌毛外,可能还含有鞭毛、外膜蛋白、血凝素等多种成分。