The human T-lymphotropic viruses: bench and bedside progress

Human T-lymphotropic virus type 1 (HTLV-1) prevalence and quantitative detection of DNA proviral load in individuals with indeterminate/positive serological results

BACKGROUND

HTLV-1 infection is currently restricted to endemic areas. To define the prevalence of HTLV-1 infection in patients living in Italy, we first carried out a retrospective serological analysis in a group of people originating from African countries referred to our hospital from January 2003 to February 2005. We subsequently applied a real time PCR on peripheral blood mononuclear cells from subjects with positive or indeterminate serological results.

METHODS

All the sera were first analysed by serological methods (ELISA and/or Western Blotting) and then the peripheral blood mononuclear cells from subjects with positive or inconclusive serological results were analyzed for the presence of proviral DNA by a sensitive SYBR Green real time PCR. In addition, twenty HTLV-I ELISA negative samples were assayed by real time PCR approach as negative controls.

RESULTS

Serological results disclosed serum reactivity by ELISA (absorbance values equal or greater than the cut-off value) in 9 out of 3408 individuals attending the Sexually Transmitted Diseases Clinic and/or Oncology Department, and 2 out 534 blood donors enrolled as a control population. Irrespective of positive or inconclusive serological results, all these subjects were analyzed for the presence of proviral DNA in peripheral blood mononuclear cells by SYBR real time PCR. A clear-cut positive result for the presence of HTLV-1 DNA was obtained in two subjects from endemic areas.

CONCLUSION

SYBR real time PCR cut short inconclusive serological results. This rapid and inexpensive assay showed an excellent linear dynamic range, specificity and reproducibility readily revealing and quantifying the presence of virus in PBMCs. Our results highlight the need to monitor the presence of HTLV-1 in countries which have seen a large influx of immigrants in recent years. Epidemiological surveillance and correct diagnosis are recommended to verify the prevalence and incidence of a new undesirable phenomenon.

Human T-cell leukemia virus type I infection in various recipients of transplants from the same donor

BACKGROUND

The human T-cell lymphotrophic virus (HTLV) causes adult T-cell leukemia-lymphoma, tropical spastic paraparesis-HTLV type I, and associated myelopathy.

METHODS

An analysis was performed of serum samples from a multiorgan donor and the five recipients. Also studied was the donor's family and the partner of one of the renal recipients. Serologic detection of anti-HTLV antibodies was carried out by enzyme immunoassay and Western blot to confirm and discriminate between HTLV types. Analysis of proviral DNA was performed by polymerase chain reaction and sequenced in the long terminal repeat region and the env gene. Peripheral blood mononuclear cell samples from all the recipients of the HTLV-I-positive organs and the donor's mother were studied.

RESULTS

Two years after transplantation, three organ recipients positive for antibodies to HTLV-I were detected (two kidney transplants and one liver). All the recipients' serum samples were negative at the time of transplantation except those from the multiorgan donor. The donor's mother was born in Venezuela and was confirmed positive for antibodies to HTLV-I. The remaining family members were negative. HTLV-I DNA sequences were recovered, amplified, and sequenced from all the samples from the HTLV-I-positive recipients and the donor's mother. The homology of HTLV-I sequences was 100% in all cases.

CONCLUSIONS

The authors are reporting the first documented case of HTLV-I infection in several transplant recipients sharing the same donor. The donor was infected by vertical transmission. HTLV-I infection has devastating consequences for some immunocompromised organ recipients. This emphasizes the need for a systematic survey of HTLV antibodies in all potential donors.