Serological diagnosis of Neospora caninum infection

Since the first isolation of the apicomplexan parasite Neospora caninum, a range of serological assays have been developed for use in dogs, cattle and a variety of other potential host species. The tests include the indirect fluorescent antibody test, the direct agglutination test and different enzyme-linked immunosorbent assays. This article reviews the principles and properties of the available tests which are discussed in relation to different applications.     

Serological diagnosis of infection with human herpesvirus type 6.

OBJECTIVE--To identify clinical consequences of acute human herpesvirus type 6 infection by hypothesising that the virus will induce similar clinical syndromes to cytomegalovirus. DESIGN--Examination of consecutive serum samples from patients with illnesses compatible with acute cytomegalovirus infection or exanthem subitum by indirect immunofluorescence for the presence of antibodies to human herpesvirus type 6. An IgG absorption step was included to avoid false positive and negative results for IgM. The criterion standard for diagnosis of human herpesvirus type 6 infection was the presence of IgM human herpesvirus type 6 antibody (titre greater than 20) and a rising titre of IgG human herpesvirus type 6 antibody without serological evidence of alternative infection. SETTING--Routine viral diagnostic and reference laboratory in the largest teaching hospital in Sydney. PATIENTS--341 Consecutive serum samples were analysed from patients with hepatitis (147 samples); infectious mononucleosis-like illness (106); screens for toxoplasma, other viruses, rubella, cytomegalovirus, and herpesvirus (38); fever in an immunocompromised patient (eight); unusual neurological (nine) or haematological syndromes (14); splenomegaly (six); and rash in a child (13). RESULTS--Three cases of acute human herpesvirus type 6 infection were identified: in one patient aged 65 with a previous diagnosis of acute non-A non-B hepatitis, one aged 25 with a glandular fever-like illness, and one aged 6 with a glandular fever-like illness. All three illnesses resolved completely. 15 Further serum samples were positive for human herpesvirus type 6 antibody but were also diagnostic for acute infection with other viruses (cytomegalovirus (nine), Epstein-Barr virus (three), and HIV (one] or had a titre of IgM human herpesvirus type 6 antibody less than 20 (two). CONCLUSIONS--Acute human herpesvirus type 6 infection in immunocompetent patients may result in a mononucleosis-like illness or an acute but self limiting hepatitis.     

The immunological diagnosis of peptostreptococcal infection

The work deals with different methods for the diagnosis of anaerobic streptococcal infection, experimentally tested and clinically approved in the examination of children with acute pneumonia. The passive hemagglutination test, the immune rosette formation test and the specific lymphocyte blastogenesis test were used for diagnosis. As sensitin and antigen, the preparation of the peptostreptococcal bacterial mass was used. The diagnostic titer of antibodies to anaerobic streptococci was 1:160. A twofold and greater increase in the number of antigen-dependent rosette-forming lymphocytes and in specific blast transformation in the presence of the diagnostic antibody titer confirms the etiological role of anaerobic peptostreptococci in the development of pneumonia in children.     

Serodiagnosis and the immunological aspects of Proteus infection. IV. Serum antibody level and the pathomorphological and bacteriological indices in experimental mixed and monoinfections of the urinary tract

In developing the serodiagnosis of the Proteus infection of the urinary tract experimental hematogenic Proteus or Proteus-Escherichia pyelonephritis was reproduced. In this infection the time course, level and avidity of serum antibodies correlated with the isolation of the causative agents from urine samples used as seed material and with histological changes in the kidneys. The serological tests revealed high titres of H-antibodies and the presence of O-antibodies, while in cases of bacteriuria not accompanied by kidney lesions only H-antibodies in low titers were detected. The results obtained in the study of immune shifts can be used for etiological diagnosis and more exact localization of the pathological process in the urinary system.     

Parasitological and immunological aspects of Trypanosoma cruzi infection in nude rats

The role of the thymus on immunity of rats against Trypanosoma cruzi infection was investigated in vivo. The athymic (nu/nu) rats were shown to be significantly more susceptible to the acute phase of the infection than the control nu/+ rats, as measured by increased parasitemia and mortality. Specific anti-T. cruzi antibodies, complement, IgM and IgG2a serum levels were determined. The results would indicate the essential role of antibodies in immunity to acute Chagas' disease through T-dependent immune response.     

Antigenic and immunogenic activity of flagella and fimbriae preparations from uropathogenic Proteus mirabilis.

The antigenic and immunogenic activities of fimbriae and flagella from three uropathogenic strains of Proteus mirabilis were compared. Flagella were obtained by mechanical treatment and fimbriae were isolated from cells by heat shock, ammonium sulfate precipitation, sodium deoxycholate and urea treatment, and gel filtration. Both preparations inoculated to mice demonstrated high antigenicity. Titers up to 1:80,000 were determined by an enzyme-linked immunosorbent assay either against the homologous or heterologous strains. When immunized mice were challenged with homologous or heterologous hematogenous infecting doses, a good cross protection was achieved only when fimbriae were used as antigens. Cross-reactivity found between the three fimbriae antisera, and the presence of common proteins in sodium dodecyl sulfate polyacrylamide gel electrophoresis patterns of fimbriae, should validate the study of these proteins to determine the existence of a shared adhesin.     

Isolation and some properties of colicin V preparations.

E. coli strain CLI(V) produces colicin V which can exist in two chemically different forms. A heat-stable, liposaccharide-protein complex is present as a main component of the cell wash. An intracellular colicin is a heat-labile and seems to be a simple protein. Preliminary experiments have shown that colicin V inhibits simultaneously synthesis of protein, RNA and DNA. Its mode of action is similar to colicins: E1, B, K and A.     

Serological and immunological studies with a hexane extract of Babesia bovis-infected erythrocytes.

Antigenic and immunogenic activities of a hexane extract from Babesia bovis-infected erythrocytes were investigated. Positive ELISA and IFAT reactions were obtained with bovine antisera to B. bovis and B. bigemina produced by natural infection and rabbit antisera to the hexane extract, respectively. In contrast, negative ELISA reactions were obtained with Anaplasma marginale antisera indicating that the antigen(s) is specific for the genus Babesia. The IFAT clearly demonstrated that the antigen was associated with the parasite and the infected erythrocyte and not present in uninfected erythrocytes. Furthermore, cross-reactions with Babesia bigemina antisera suggested that serological cross-reactivity in bovine Babesia species is at least due in part to lipid or lipid-associated antigens.     

Clinical, parasitological and immunological aspects of experimental infection with Trypanosoma evansi in dogs

This research investigated the pattern of antibody response by means of enzyme linked immunosorbent assay (Elisa) and indirect fluorescent antibody test (IFAT) through the course of experimental Trypanosoma evansi infection in dogs. Clinical and parasitological features were also studied. The average prepatent period was 11.2 days and parasitaemia showed an undulating course. Biometrical study of parasites revealed a mean total length of 21.68mm. The disease was characterized by intermittent fever closely related to the degree of parasitaemia and main clinical signs consisted of pallor of mucous membrane, edema, progressive emaciation and enlargement of palpable lymph nodes. Diagnostic antibody was detected within 12 to 15 days and 15 to 19 days of infection by IFAT and Elisa, respectively. High and persistent antibody levels were detected by both tests and appeared not to correlate with control of parasitaemia