Effect of Rous associated virus number 7 on lymphoid cells and tissues of the chicken

Infection of chicks or chick embryos with Rous associated virus number 7 (RAV-7) led to a decreased blastogenic response to Concanavalin A (Con A) by lymphocytes isolated from the spleen and thymus. Chicks infected with RAV-7 8 days after hatch manifested decreased Con A blastogenesis 5 weeks postinfection, while chicks infected in ovo at 10 days of incubation showed an unusual pattern of cell density dependent decreased blastogenesis two weeks post-hatch (three weeks post-infection). Histopathological examination of tissues from RAV-7 infected chicks revealed evidence of lymphoid organ involution and widespread lymphoproliferative lesions by 3 weeks of age. The combination of decreased in vitro lymphoid blastogenesis and in vivo lymphoproliferation suggests that RAV-7 interacts with lymphocytes in a fashion that has not previously been described in the chicken.     

Serotyping of Haemophilus pleuropneumoniae in the Netherlands: with emphasis on heterogeneity within serotype 1 and (proposed) serotype 9

Four hundred and forty-three Dutch field isolates of Haemophilus pleuropneumoniae were serotyped by rapid slide agglutination (RSA) using specific antisera against serotypes 1 to 5 and against the recently proposed types 6 to 9. The predominant serotypes were 9 (49%) and 2 (32%). Serotypes 1, 3, 5, 7 and 8 were isolated in small numbers: together they accounted for 3% of the total. Five percent of the isolates were not typable either due to autoagglutination or because they were not agglutinated by any of the available antisera. The remaining 49 strains (11%) agglutinated in more than one antiserum and could therefore not be properly classified. Forty-four of these 49 strains agglutinated in both anti type 1 and anti type 9 serum. Antigenic relationships between serotype 1, serotype 9 and isolates reacting with both antisera were studied using immunodiffusion and RSA with adsorbed sera. Serotype 9 strains appeared not to be a homogenous group. Isolates agglutinating exclusively in anti type 9 serum can be divided into two groups: one closely related and another hardly related to serotype 1. Serotype 9 reference strain 13261 belongs to the latter. Type 1 + 9 strains have antigens in common with serotypes 1 and 9, but they also have their own specific antigenic material. Such strains are proposed as a new serotype 10.     

Effect of intratesticular inoculation with Aujeszky's disease virus on genital organs of boars

Ten 8-10-month-old Belgian Landrace boars were intratesticularly inoculated with 500 TCID50 of a virulent Belgian Aujeszky's disease virus (ADV) isolate (75V19) in 0.1 ml volume. One control boar was similarly inoculated with phosphate-buffered saline solution. The genital organs of six inoculated boars were examined by virus isolation and immunofluorescence. In spite of high virus titers, the fluorescence in the testicles remained limited to a few small foci in the interstitial connective tissue and tunica albuginea at or close to the inoculation site. Neither virus replication, necrosis nor inflammatory lesions could be demonstrated in the epithelium of the seminiferous tubules. However, virus replication was regularly demonstrated in the serosa covering testicles, plexus pampiniformis, ductus deferens and tunica vaginalis. Virus was also isolated from the scrotal fluid. It is suggested that the serosa is the primary target tissue for ADV. The other four boars were inoculated to study the effect of ADV on semen. Severe morphologic alteration and lowered sperm cell concentrations were observed during several weeks after inoculation or until slaughter at 47, 53 and 58 days post inoculation. Virus was isolated from semen of only two out of four boars examined at 9 and 10 days post inoculation.     

A comparison of three rapid diagnostic methods for the detection of rotavirus infection in calves

Three techniques for the detection of rotavirus in faecal samples from calves with neonatal gastroenteritis were compared. A preliminary study indicated that reverse passive haemagglutination (RPHA) was at least as sensitive as the enzyme-linked immunosorbent assay (ELISA). These two immunoassays were compared with the detection of viral RNA by polyacrylamide gel electrophoresis (PAGE) on 209 field samples. Of the 77 samples in which at least one test gave a positive result, 69 were positive by both RPHA and PAGE, but only 49 were also positive by ELISA, indicating a lower sensitivity for the latter test. The overall agreement between RPHA and PAGE was 96%. The reasons for the discrepancies between the tests are discussed.     

Virulence factors in Escherichia coli isolated from piglets with neonatal and post-weaning diarrhea in Japan

A total of 567 strains of Escherichia coli were isolated from piglets with neonatal diarrhea (ND) or post-weaning diarrhea (PWD) in Japan. They were investigated for enterotoxigenicity and possession of adhesins and O antigens. There were clear differences between the strains of ND origin and those of PWD origin in the occurrence of enterotoxigenic E. coli (ETEC) strains, type of enterotoxin and frequency of adhesins: ETEC was found in 77 (25.7%) of 300 strains of ND origin and in 137 (51.3%) of 267 strains of PWD origin. ETEC strains producing heat-labile enterotoxin (LT) or heat-stable enterotoxin (STa), alone or in combination were evenly distributed among the strains of PWD origin. In contrast most of the ETEC strains of ND origin produced LT alone. Adhesins appeared in 42 (54.5%) of 77 ETEC strains of ND origin and in 36 (26.3%) of 137 ETEC strains of PWD origin. Adhesins were less common in ETEC strains of PWD origin than in those of ND origin. Some K99-positive ETEC strains of PWD origin produced both LT and STa. There was a similarity in the distribution of O antigens, particularly O149 and O157, between the strains of ND origin and those of PWD origin.     

Antigenic variation of porcine transmissible gastroenteritis virus detected by monoclonal antibodies

Mouse myeloma cells (SP2/O) were fused with spleen cells from BALB/c mice immunized with detergent-solubilized antigen of purified virus, and 21 monoclonal (MC) antibodies reactive in enzyme-linked immunosorbent assay with the TO-163 strain of porcine transmissible gastroenteritis (TGE) virus were obtained. Of these MC antibodies, 14, 6 and 1 were IgG1, IgG2a and IgM, respectively. All of the MC antibodies contained light chains of the kappa type. Of these MC antibodies, 8 were found to have neutralization (NT) activity against the TO-163 strain. Comparison of 7 strains of TGE virus by NT tests using our panel of MC antibodies confirmed their close antigenic relationships, but also revealed the occurrence of distinct antigenic differences. These results suggest that there may be at least 6 different epitopes involved in NT reaction on the virion of the TO-163 strain. This notion was confirmed by the competitive binding assay.     

Characterisation of the outer membrane protein antigens of British field isolates of Moraxella bovis

Outer membranes of a single isolate of Moraxella bovis were prepared and their purity evaluated by a comparison of the iodinated proteins from whole cells and on outer membranes. The protein patterns of the outer membranes of 10 isolates were examined by SDS-polyacrylamide gel electrophoresis, and the antigenic relationship between proteins of different isolates determined by immunoblotting, using antiserum produced against the outer membrane of the single isolate of M. bovis. The overall protein pattern of the different isolates was similar although not identical, but, significantly, only three separate immunogenic proteins were common to all the isolates under examination.     

Exploration of the cellular mediated immunity by the blastogenesis test during chronic brucellosis in human

The diagnosis of the chronic, human brucellosis is frequently difficult and usually needs experimental methods. This paper describes a lymphocyte stimulation test with a Brucella antigen and the results of this test concerning 45 brucellic or not brucellic patients. It is concluded that this test is interesting, especially for the chronic and sero-negative Brucellosis diagnosis.     

Decrease in catalase activity of cultured cells by Mycoplasma gallisepticum infection

The effect of Mycoplasma gallisepticum infection on the host cell catalase activity was histochemically examined in cultured chicken embryo fibroblasts (CEF) and kidney cells. The activity in normal cells was detected as fine, brown granules in the cytoplasm, which appeared ultrastructurally to correspond to anucleoid microbodies. By infecting cultured cells with a CEF-passaged strain of M. gallisepticum, the catalase-positive granules clearly decreased in amount, whereas the UV light-killed mycoplasma and the original strain failed to decrease the granules. The cell-passaged strain was able to induce cytopathic effects and this appeared to be due to its enhanced adherent ability as compared with the original strain. These findings suggest that attachment of viable organisms to cells is crucial to decrease the catalase activity and that the decreased activity may be an important process for the subsequent development of cytopathic effects.