Comparing electron microscopy and a competitive blocking ELISA in the detection of rotaviruses in porcine faeces.

Analysis of 476 faecal samples from diarrhoeic piglets was performed using electron microscopy (EM) and a competitive blocking (CB)-ELISA based on monoclonal antibodies to the VP6 protein of group A rotavirus. Rotavirus was detected by EM and/or CB-ELISA in 111 (23.3%) samples. Of these, all groups of rotavirus were identified in 83 (74.8%) samples by EM (EM+), while group A rotavirus was identified in 90 (81.1%) samples by CB-ELISA (ELISA+). However, only 62 (55.9%) of samples were positive using both detection methods. The finding of 28 (25.2%) EM-/CB-ELISA+ samples illustrated the high sensitivity of the CB-ELISA method. On PCR analysis, groups B and C rotavirus was found in 3 and 16 of 19 EM+/CB-ELISA- samples, respectively. Although the study illustrates the high sensitivity of a CB-ELISA in rotavirus detection, the findings highlight the need to use a range of diagnostic methods in detecting these viruses in clinical samples.

Characterisation of immunosuppression in rabbits after infection with myxoma virus.

Myxoma virus (MXV) causes the systemic disease myxomatosis in the European rabbit. Despite many in vitro studies on the function of MXV immunomodulatory proteins and detailed molecular knowledge of virus, little is known about the dynamics of interaction of the virus with the integrated host-immune system during infection. In this study changes in haematological profile, changes in lymphocyte subset distribution and non-specific proliferation activity of lymphocytes from different lymphoid compartments on the 2nd, 4th, 6th, 9th and 11th day after experimental infection of rabbits with MXV strain Lausanne was characterised. The relationship between alterations of immune parameters and dynamic of virus dissemination through the body was investigated. Haematological changes included moderate leucopenia with significant lymphopenia, neutrophilia, monocytosis and eosinopenia. A decrease of T cells including CD4+ and CD8+ and increase of CD79alpha+ were observed in draining popliteal lymph node 4 days after virus inoculation. From day 6, comparable changes were seen in collateral popliteal lymph node, spleen and peripheral blood. From day 9, the mentioned lymphocyte subsets tended to reach their original state in all of these lymphocyte compartments except draining popliteal lymph node. In thymus, MXV infection affected mainly CD4+CD8+ double positive thymocytes. On the other hand, proliferation activity of lymphocytes determined by the proliferation assay with plant-derived mitogens was significantly reduced from day 4 or 6 and remained reduced until the end of experiment in all observed lymphoid organs. Presence of MXV in respective lymphoid compartments preceded changes in lymphocyte subset distribution or lymphocyte activity.

Development of direct ELISA for the determination of 4-nonylphenol and octylphenol.

Development of direct competitive enzyme-linked immunoadsorbent assays (ELISAs) based on polyclonal and monoclonal antibodies raised against 4-n-alkylphenol hapten mimics is described. A strong tendency to recognize 4-nonylphenol (NP) and 4-octylphenol (OP) as a total analyte amount was indicated by cross-reactivity pattern established for two polyclonal antibodies. These antibodies were employed for development of class-selective assays exhibiting IC(50) values around 40 microg.L(-1) for technical 4-NP. Specificity of the monoclonal antibody 4H6 and additional two polyclonal antibodies allowed sensitive detection of linear long-chain forms of 4-n-alkylphenols (4-n-AP). The assays incorporating these antibodies offer a potential for detecting the minor fraction of NP/OP isomer spectrum having IC(50) = 11.5 microg.L(-1) for 4-n-NP. No cross-reactivity interference was indicated for linear alkylbenzene sulfonates and phenolic compounds. To interpret the measured data in terms of analytical equivalents, a reliable relationship between the assay responses and AP content of contaminated samples should be verified and validated.