Monoclonal anti-idiotypes for the rapid detection of human cytomegalovirus

Human fibroblasts are permissive for porcine cytomegalovirus in vitro

BACKGROUND

Xenotransplantation with pig organs is being considered to alleviate donor organ shortages; however, the risk of introducing porcine viruses into humans is heightened in this setting. The goal of this study was to determine the infectious potential of porcine cytomegalovirus (PCMV), a xenozoonotic virus of interest, in human fibroblasts in vitro.

METHODS

Confluent human cells were incubated with live PCMV, heat-killed PCMV, or medium alone. Infection was investigated by testing for viral-induced cytopathic effect, assaying viral transcription by nested RT-PCR and subsequent sequencing, and detecting viral protein expression by Western blotting. Plaque neutralization experiments were also performed.

RESULTS

Cells incubated with PCMV demonstrated significant cytopathic effect by 7 days postinfection, and reverse-transcriptase polymerase chain reaction sequencing identified PCMV DNA polymerase in these infected cells. In Western blots, monoclonal antibodies (mAbs) to human CMV glycoprotein B and pig serum presumed to contain anti-PCMV antibodies detected characteristic proteins in experimentally infected human cells and positive controls but not in negative controls. Furthermore, one of these mAbs and the pig serum neutralized PCMV infection in vitro.

CONCLUSIONS

These results are a first demonstration that PCMV can infect human fibroblasts in vitro.

Internal image rabbit anti-idiotypic antibody detects sheep antibodies to the bluetongue virus core protein VP7

BACKGROUND

Rabbit polyclonal anti-idiotypic antibodies (anti-Id) were generated against three murine monoclonal antibodies (MAbs) specific for the group-specific antigen VP7 of bluetongue virus (BTV) by the sequential immunization method. It was demonstrated by serological tests that part of the anti-Id possesses the characteristics of internal image anti-Id. By affinity purification against the individual MAbs, the internal image anti-Id, designated RAb2-A, was isolated and identified as specific for the MAb, M1875.

OBJECTIVES

To examine the ability of RAb2-A to detect sheep anti-VP7 antibodies by recognition of the common idiotype (Idx).

STUDY DESIGN

Affinity-purified RAb2-A IgG, along with VP7, was applied on the solid-phase of ELISA plate and the membrane for Western blot analysis to detect anti-VP7 antibodies from sheep that were immunized with VP7 or were experimentally infected with BTV. An inhibition ELISA was employed to determine whether sheep anti-VP7 and M1875 recognize the same or similar epitope(s).

RESULTS

RAb2-A recognised the Idx on anti-VP7 antibodies from sheep that were either immunized with VP7 or experimentally infected with BTV. Specificity of the reaction was confirmed by the observation that RAb2-A did not react with normal sheep serum or sheep antibodies against epizootic haemorrhagic disease of deer virus, a bluetongue-related disease virus in the Orbivirus genus.

CONCLUSION

The ability of RAb2-A to detect anti-VP7 antibodies through recognition of the Idx suggests that RAb2-A can be used as a probe to detect anti-BTV antibodies.

Anti-idiotypic mimicry of a neutralizing epitope on the glycoprotein B complex of human cytomegalovirus

Experiments were carried out to investigate the ability of rabbit anti-idiotype antibodies (Ab2), directed against an anti-human cytomegalovirus monoclonal antibody (Ab1), to induce neutralizing antibodies specific for the immunodominant glycoprotein B viral complex. Mice immunized with Ab2 produced anti-Ab2 (Ab3) that was both antigen and idiotype specific with regard to Ab1. We conclude that the Ab2 antibodies mimicked a neutralizing epitope and acted as a network antigen for inducing a specific anti-human cytomegalovirus antibody response in this experimental system.

A novel approach to the laboratory diagnosis of Chlamydia trachomatis infections using monoclonal anti-idiotypic antibodies

We have developed a novel enzyme immunoassay (EIA) for the specific detection of Chlamydia trachomatis utilizing a monoclonal anti-idiotypic antibody to an antibody directed against a chlamydia specific epitope on 60 kDa heat-shock protein (HSP60). The basis of the assay is the inhibition of the binding of idiotype to anti-idiotype by antigen present in test samples. Two configurations of the assay were developed: a blocking EIA and a competition EIA. Greater sensitivity was observed using the competition EIA, with the assay detecting purified recombinant HSP60 and purified chlamydia in a concentration-dependent manner from 0.01 to 10 micrograms protein and from 0.5 to 12 micrograms total protein, respectively. The assay is highly specific and offers several potential advantages over currently available EIAs for the detection of this pathogen.