Biology of the group E streptococci: a review

Group E streptococci are identified by a group antigen consisting of a cell wall rhamnose-glucose polymer. Other specific cell wall polysaccharides separate the group into at least six serotypes (II, IV, V, VI, VII and VIII). No species name has been accepted for the group E Streptococcus, although the organism is often designated as Streptococcus infrequens or S. lentus. Recently, the name S. porcinus has been proposed for a species that would include streptococci of groups E, P, U and V. Group E streptococci are fairly widely distributed in animals, especially swine, and are occasionally isolated from bovine milk. They cause streptococcal lymphadenitis of swine, an economically important disease, particularly in the United States. They do not appear to be the primary cause of any other disease or condition. The organisms enter the swine host through the mucosa of the pharyngeal or tonsillar surfaces, and are carried to the lymph nodes, primarily of the head and neck region, where abscesses are formed. Cell wall antigens induce the formation of serum agglutinins; a microtitration agglutination test, based upon reactions involving the type IV antigen, is considered a reliable test for detection of infection in animals. Antigenic components include group and type antigens, extra-cellular enzymes, and an antiphagocytic factor which may be associated with virulence of the organism and with protective immunity to streptococcal lymphadenitis of swine. This factor, a surface protein, develops on cells cultured in media fortified with serum, rendering the cells resistant to phagocytosis by porcine leukocytes. The classification, morphology, physiology, biochemistry and nutrition of the group E streptococci, and methods for their isolation, cultivation, and identification are reviewed.     

Susceptibility of colostrum-deprived swine of various ages to streptococcic lymphadenitis

The effect of age on susceptibility of young pigs to streptococcic lymphadenitis was investigated. Twenty-nine cesarean-derived, colostrum-deprived pigs were allotted to 7 groups exposed to type IV group E Streptococcus (GES) at 5, 14, 28, 35, 56, 70, and 84 days of age. Four cesarean-derived, colostrum-deprived pigs were maintained as nonexposed controls. Six naturally farrowed, susceptible controls were exposed to GES at 63 to 84 days of age. All exposed pigs were killed and necropsied 28 days after exposure. Lesions of streptococcic lymphadenitis were not observed in pigs exposed at 5 or 14 days of age, except for 1 microabscess in a mandibular lymph node in a pig exposed at 14 days, but GES was recovered from 11% of lymph nodes examined from pigs of those age groups. Lesions and GES-positive lymph nodes were frequent in cesarean-derived, colostrum-deprived pigs exposed at 28 days and older and in susceptible controls. Serologic response to exposure, as determined by microtitration agglutination test and bactericidal test, was observed only in pigs exposed at 14 days and older. The absence of abscess development in pigs exposed at 5 or 14 days of age was not caused by antibody or failure of infecting organisms to reach the target organs.     

Humoral Antibody Responses of Swine Infected Experimentally with Group E Streptococcus I. Whole Cell Agglutinin Response

Reference streptococcal antisera and sera collected from swine infected experimentally (by intranasal inoculation or contact exposure) with group E Streptococcus (GES) were studied in a tube agglutination system using whole GES cells.

Specificity studies revealed common group specific antigen among GES serotypes I and III, GES strains devoid of type specific antigen (untypable by ring precipitin testing) and group P and group U Streptococcus. The group specific antigens were not agglutinated by GES type specific antisera or by group specific antisera against Streptococcus groups A, B, C, D, F, G, H, K, L, M, N, or O. Results of the study suggested that GES serotypes I and III are invalid; i.e., they are devoid of type specific antigen.

Groug E Streptococcus type specific antigens II, IV, and V were agglutinated significantly only by their homologous antisera.

Experimentally infected swine developed significant titers against both the group and type specific antigen of GES. Antibodies appeared from three to eight weeks postexposure and persisted for the duration of the experiment (six months). The potential utilization of the whole cell agglutination (WCA) test for detection of GES carrier swine is discussed.

     

Immunity to Lancefield's group E Streptococcus: passive protection of swine

Healthy swine from one source were randomly allotted to 3 groups of 3 pigs each. Troup I and II pigs were parenterally dosed with serum obtained from swine in the convalescent stage of streptococcic lymphadenitis of swine. Group III pigs were contact controls. The swine of all groups were orally exposed to Lancefield's group E Streptococcus sp. During the next 3 weeks, the controls evidenced little resistance to the development of streptococcic lymphadenitis of swine, whereas the principals evidenced considerable resistance to development of the disease.     

Comparison of the microtitration agglutination test and the enzyme-linked immunosorbent assay for the detection of herds affected with swine dysentery

A method was designed to evaluate and compare the microtitration agglutination test (MAT) and the enzyme-linked immunosorbent assay (ELISA) to detect antibodies in swine sera to Treponema hyodysenteriae and thereby establish a method for determining the prevalence of swine dysentery (SD) in herds. According to sampling criteria based on the hypergeometric distribution, sera were collected from 3 age groups of swine from farms having a history of SD on the premises (SD+) recently or being free of the disease (SD-). The highest degree of test sensitivity was obtained when sera from market age swine were evaluated with the ELISA. Of 14 SD+ herds from which sera were obtained from market-age swine, 13 were positive with the ELISA (93%); none of the 8 SD- herds was positive. The detection rates of individual swine in the SD+ herds for the 2 tests by age group were as follows: MAT--adult swine 1.4%, market-age swine 6%, and weaned pigs 0.8%; ELISA--adult swine 16%, market swine 31%, and weaned pigs 0.5%.     

Separation of a Soluble Antigen and Infectious Particles of Bovine Viral Diarrhea Viruses and their Relationship to Hog Cholera

A soluble antigen present in infectious tissue culture fluids was separated from the infective virus particle by ultracentrifugation of two serologically related strains of bovine viral diarrhea viruses, NADL-MD and Oregon C24V.

Neutralizing antibodies against the two viruses were absent in four hog cholera antisera, but present in significant titer in the commercially prepared antiserum. Precipitin tests utilizing the agar double diffusion technique formed a single line of identity between the concentrated soluble antigen of both viruses and NADL-MD and hog cholera antisera. No lines were observed using concentrated virus pellet and noninfected BEK cell antigens or control SPF calf and swine sera.

     

Serological cross-reactivity of porcine reference antisera to Mycoplasma hyopneumoniae, M. flocculare, M. hyorhinis and M. hyosynoviae indicated by the enzyme-linked immunosorbent assay, complement fixation and indirect hemagglutination tests.

The enzyme-linked immunosorbent assay (ELISA) indicated significant cross-reactivity between the antigens of Mycoplasma hyopneumoniae ( HyoP ) and M. flocculare (Floc), another porcine mycoplasma of wide distribution but uncertain pathogenic significance, when porcine antisera of each specificity were tested against HyoP antigen. The titers of the anti-Floc sera ranged from threefold to 13-fold less than the titer of the anti- HyoP reference serum at different times after immunization. These values ranged from onefold less than to fourfold greater than the minimal positive titer of 80. The antisera to the other porcine mycoplasmal antigens [i.e. M. hyorhinis ( HyoR ) and M. hyosynoviae ( HyoS )] reacted less strongly to HyoP antigen but titers only slightly less than to slightly greater than the minimal positive titer were noted for some sera. Cross-reactivity was also detected by the complement fixation test, although the titers for this test were generally lower than for the ELISA, presumably reflecting lower sensitivity of the complement fixation test. Positive indirect hemagglutination titers to HyoP antigen were also observed for both anti-Floc sera obtained at one or more times during the immune response. With two exceptions (one anti- HyoR serum with a complement fixation titer of 16 and one anti- HyoR serum with an indirect hemagglutination titer of 10), none of the anti- HyoR or anti- HyoS sera had detectable indirect hemagglutination or complement fixation titers to HyoP antigen at any time after immunization. The levels of cross-reactivity detected by the complement fixation test and indirect hemagglutination and, especially, the ELISA would be of significance for the development of any practical sero-diagnostic test for mycoplasmal pneumonia of swine.     

Evaluation of an enzyme-linked immunosorbent assay for detection of Eperythrozoon suis antibodies in swine.

An ELISA was developed and tested to detect antibodies to Eperythrozoon suis in swine. Results were compared with those of the indirect hemagglutination (IHA) test. Antigen isolated from swine heavily infected with E suis was used for both tests. Comparison of the ELISA with the IHA test revealed a significant (P less than 0.001) correlation between results. Of 114 samples obtained from 9 swine infected with E suis, 87.7% were seropositive (titer greater than or equal to 200) via the ELISA, and 80.7% were seropositive (titer greater than or equal to 20) via the IHA test. The sensitivity of the ELISA was greater than that of the IHA test. All blood samples obtained from specific-pathogen-free swine tested negative for E suis antibody. Cross-reactions were not observed between E suis antigen and antisera against various swine and cattle disease agents using ELISA. We concluded that the ELISA may be used for rapid and effective diagnosis of infection with E suis in swine.     

Communications: Specificity of the Channel Catfish Antibody to Edwardsiella ictaluri

Abstract

The specificity of channel catfish Ictalurus punctatus serum antibody to Edwardsiella ictaluri was characterized by microtiter agglutination assay. There was no correlation between antibody titer to Aeromonas hydrophila and antibody titer to E. ictaluri in wild or feral channel catfish. Anti-E. ictaluri antibodies in naturally infected channel catfish were not removed by adsorption by nine other species of bacteria found in the channel catfish intestine and fish ponds. Channel catfish immunized with nine other species of bacteria did not develop substantial antibody titer to E. ictaluri. The antibody response of channel catfish to E. ictaluri is highly specific, and the microtiter agglutination test is a specific indicator of previous exposure to E. ictaluri     

Immunity to Lancefield's group E. streptococcus: flank inoculation of susceptible and immune swine

Healthy swine flank inoculated with Lancefield's group E Streptococcus sp developed characteristic signs of streptococcal lymphadenitis of swine; however, abscesses were found in prefemoral lymph nodes rather than in cervical lymph nodes. After 6 months, swine (recovered from the cervical form of streptococcal lymphadenitis of swine caused by oral exposure to group E Streptococcus) were flank inoculated with group E Streptococcus sp. Only transitory signs of diseases developed and abscesses did not develop in the prefemoral lymph nodes.     

A rapid microtitration serum agglutination test for the detection of contagious equine metritis antibodies

A microtitration serum agglutination test, based on that used for brucellosis, has been developed to detect antibodies in the sera of horses exposed to the contagious equine metritis (CEM) organism. Two known positive sera were tested 100 times in 15 separate tests. The results were reproducible to within a twofold range. The test is capable of being carried out within 100 min.     

Identification of Bordetella avium antigens recognized after experimental inoculation in turkeys

Sera and tracheal washings (TW) were used to identify antigens of Bordetella avium recognized during experimentally induced bordetellosis in young turkeys. Pooled sera and TW were examined for antibody by a microtitration agglutination test and by western immunoblotting. In addition, comparable samples collected from 1-day-old turkeys and uninoculated control turkeys also were examined. At least 8 outer membrane proteins of B avium were recognized in immunoblots of sera and TW from infected turkeys. Reactivity of TW in immunoblots was qualitatively similar but less intense, compared with reactivity of corresponding sera collected on postinoculation (PI) weeks 2, 3, and 4. Molecular weights of the major outer membrane proteins of B avium recognized by sera and TW at PI week 4 were 100,000, 97,000, 36,000, 31,000, 21,000, 18,000, 14,000, and less than 14,000. A protein with a molecular weight of 55,000 reacted nonspecifically in all samples tested. Antibody, detectable by microtitration agglutination, was in sera of 1-day-old turkeys and in sera and TW of B avium-infected turkeys during PI weeks 2 to 4.     

A Study of Complement-fixation and Serum Agglutination Tests on Vibrio fetus Infected and Immunized Cattle

Complement-fixation (CF) and tube agglutination (TA) tests for demonstration of Vibrio fetus antibodies were conducted on the sera of three groups of ten heifers. One group was vaccinated subcutaneously with a commercial V. fetus var venerealis bacterin and challenged intra-utero, at the external os cervicus one month later; the second was infected only and the third vaccinated only.

The vaccinated cattle developed high CF serum titers, but no such increase was observed in animals infected only. A moderate increase in serum antibody titers was demonstrated by the TA test following either infection or vaccination; although titers observed were not higher than those observed in the sera of some apparently normal uninfected animals. The group receiving both vaccine and challenge was the only one in which significant serum antibody titers were demonstrable by the TA test. The sera of these animals also had significant titers in the CF tests.

The CF and TA tests detected serum antibodies produced by the parenteral inoculation of V. fetus antigen. These two tests were of limited value in detecting serum antibodies from animals with genital V. fetus var venerealis infection, although the formation of local antibodies was demonstrable by the vaginal mucus agglutination test.

     

The detection of transmissible gastroenteritis viral antibodies by immunodiffusion.

Precipitating antibodies against transmissible gastroenteritis viral antigens were detected by the immunodiffusion test in two transmissible gastroenteritis viral hyperimmune antisera and in antiserum prepared against haemagglutinating encephalomyelitis virus but not in sera from several species of normal animals, in antisera prepared against a variety of othet viruses and bacteria or sera from swine with bacterial enteritis. When the immunodiffusion test was compared with the virus neutralization test for the detection of transmissible gastroeneritis viral antibodies in 20 swine sera certain samples which contained high titres of virus neutralizing antibodies failed to produce precipitation while other sera were positive in the immunodiffusion test although their virus neutralizing antibody titres were relatively low. Precipitating antibodies were also detected by immunodiffusion in several samples of milk whey from a sow which had been vaccinated with inactivated transmissible gastroenteritis virus.     

Evaluation of ELISA for the detection of Toxoplasma antibodies in swine sera

Enzyme-linked immunosorbent assay (ELISA) is compared with the indirect fluorescent antibody test (IFAT), the indirect haemagglutination test (IHAT) and the latex agglutination (LA) test for the detection of toxoplasma antibodies in swine sera. The 100 swine sera examined represent ELISA values from greater than 0 to 154 EIU. The agreement was highest (0.67) between ELISA and IFAT with an ELISA cut-off value of 30 EIU, and between ELISA and the LA test with an ELISA cut-off value of 50 EIU (0.74). All sera giving less than 10 EIU were negative in the other tests, and all those with greater than 70 EIU were positive in 1, 2 or all of the reference tests. In order to avoid false positive results with ELISA, all sera giving 10-70 EIU should be confirmed with a test which has a good specificity, e.g. IFAT. ELISA is a sensitive test and is highly suitable for the screening of large amounts of samples, but it may be too complicated for screening toxoplasma antibodies in the laboratories of abattoirs.     

Is canine leptospirosis underdiagnosed in southern Ontario? A case report and serological survey

An eight-year-old city-dwelling Cairn Terrier was presented to a veterinary hospital in acute renal failure with evidence of hepatic insufficiency. The dog was treated symptomatically over three days, during which time vomiting was largely controlled, but it became jaundiced as hepatic insufficiency worsened. Leptospira pomona was demonstrated in large numbers by immunofluorescent staining of urinary sediment. It was isolated and its identity confirmed as L. pomona genotype kennewicki. The source of the infection was thought to be raccoons.

Sera from 474 blood samples submitted for diagnostic purposes to two clinical pathology laboratories in southern Ontario were examined with the microscopic agglutination test for antibodies to selected leptospiral serovars. Of the sera tested, 39.2% reacted at titers ≥1:100 with one or more serovars, the majority of all sera (26.2%) reacting at low titers to canicola or icterohaemorrhagiae, or both. These reactions likely resulted from vaccination. A smaller proportion reacted to other serovars tested: autumnalis (3.8%), bratislava (8.2%), grippotyphosa (1.9%), hardjo (3.0%), and pomona (3.2%). Among dogs reacting to these latter serovars (other than bratislava), many had broadly cross-reacting and relatively high titers. One dog with a titer of 1:800 to pomona had had a disease typical of leptospirosis two years previously. Three other dogs with high titers to autumnalis, bratislava, or mixed serovars had clinical histories compatible with leptospirosis.

We suggest that leptospiral bacterins for dogs in Ontario be broadened to include at least serovars autumnalis and pomona.

     

Studies of Escherichia Coli in Gnotobiotic Pigs: II. The Immune Response*

The immune response of orally infected and parenterally vaccinated (E. COLI 08:K.:H21) gnotobiotic pigs was studied by bactericidal and indirect hemagglutination test methods. The bacterial agglutination test proved to be of no value in this study.

The results demonstrated that antibody was detectable within 8 days following oral infection, but the titers remained very low until after the pigs were vaccinated intravenously. The titers of the sera were markedly increased following intravenous vaccination.

There was no detectable absorption of antibody from the gut of gnotobiotic pigs fed immune serum at 4 to 6 days of age and no detectable difference between the immune response of these pigs and those not fed serum.

     

II. Detection of the Virus in Swine Tissues by Means of the Modified Direct Complement-Fixation Test

The modified direct complement-fixation test, supplemented with unheated normal calf serum, was used to demonstrate antibodies in sera of swine immunized to African swine fever virus. These antibodies did not react in the ordinary direct non-supplemented complement-fixation test.

African swine fever complement-fixing antigen in infected swine tissue is not denatured by extraction with fat solvents. Consequently, good antigens devoid of non-specific reactivity were obtained by extraction with a mixture of acetone and ether.

The virus was detected in infected swine tissue harvested one day after beginning of pyrexia. The modified direct complement-fixation test demonstrated cross-reactions between the six strains of virus studied.

     

凝集试验检测兰氏D群链球菌血清抗体方法的建立

建立凝集试验,用于检测兰氏D群链球菌血清抗体.采用兰氏D群链球菌C55914株制成凝集试验抗原,制备的抗原与兰氏D群链球菌兔高免阳性血清、猪正常免疫阳性血清发生凝集反应,不与健康兔阴性血清及健康猪阴性血清发生凝集反应,与链球菌兰氏C群、兰氏E群、巴氏杆菌A群、B群阳性血清呈阴性反应.试验证明,凝集试验能够快速地检验出兰...     

Response of Gnotobiotic Pigs to Escherichia coli

In a study of the response of gnotobiotic pigs to coliform infections, 45 one-week-old germfree pigs were divided into five groups and each group was inoculated orally with a different strain of Escherichia coli. Three of these were enteropathogenic swine strains, P307[08:K87(B), K88 a,b (L):H19]; P570 [0138:K81]; P568[0141:K85a,b(B), K88a,b(L):H4], one was a virulent human strain, H224, [026:K60(B6)], and one was a non-enteropathogenic swine strain, P581[OX13:K68]. It was attempted to protect a portion of the pigs with orally administered specific antisera and sera from non-immunized specific pathogenfree (SPF) pigs. Observations were made on the clinical response, bacterial counts of feces and intestinal contents, gross pathological changes, distribution of the organisms in organs and serum hemagglutinin titers.

Infection with E. coli P307 resulted in diarrhea, dehydration and death, unless the pig was protected with specific antiserum. The pigs infected with E. coli P570 had a transient diarrhea but retained their appetites and recovered. Those infected with the other three strains remained healthy throughout. No circulating hemagglutinating antibody against the test strains of E. coli could be detected in any of the pigs seven days or earlier post-inoculation.

Relationship could not be established between the numbers of viable E. coli in the feces and the presence of clinical colibacillosis. Orally administered specific antiserum afforded protection against strain P307, but did not reduce the number of E. coli in the gut or alter their distribution in the internal organs. This suggested that the protective effect of specific antibody in the intestine was due to its action on a metabolite (enterotoxin) produced by E. coli P307 rather than the organism itself.