Pathogen inactivation of Leishmania donovani infantum in plasma and platelet concentrates using riboflavin and ultraviolet light

BACKGROUND AND OBJECTIVES

Leishmania is transmitted by the bite of the phlebotomine sandfly or by transfusion of infected blood products. Leishmaniasis currently poses a significant problem in several parts of the world, and is an emerging problem in others. The Mirasol PRT technology is based on the use of riboflavin and ultraviolet light to generate chemical reactions in the nucleic acids of pathogens, which prevents replication and leads to inactivation. The intent of this study was to examine the ability of the Mirasol PRT System to kill the Leishmania parasite in human plasma and platelet concentrates.

MATERIALS AND METHODS

In visceral Leishmaniasis, amastigotes are present in the blood and in the reticuloendothelial system within monocytes. For each unit of plasma or platelets treated, isolated mononuclear cells obtained from 100 ml of normal donor whole blood were incubated with 1.0 x 10(8) Leishmania donovani infantum promastigotes to produce amastigote-laden macrophages. The infected macrophages were added to 250 ml of human plasma or to 250 ml of platelet concentrates. Infected units were cultured pretreatment in 10-fold serial dilutions to determine the limits of detection. Thirty millilitres of 500 microM riboflavin was added to each unit, which was then illuminated with 5.9 J/cm2 of ultraviolet light (6.24 J/ml). After treatment and after 2 months of frozen storage, plasma units were cultured in 10-fold serial dilutions. Platelets were cultured on the day of treatment and on day 5 of storage post-illumination.

RESULTS

A 5 log reduction of Leishmania was demonstrated in five of six units of plasma, and a 7 log reduction of Leishmania was demonstrated in one plasma unit. A 5 log reduction of Leishmania was demonstrated in five of six units of platelets, and a 6 log reduction of Leishmania was demonstrated in one unit.

CONCLUSIONS

There is no donor screen for Leishmania and other pathogens constantly emerging in our blood supply. The Mirasol PRT System for Platelets and Plasma is an effective means of killing Leishmania and other emerging pathogens in these blood products.

Serial quantitation of HPV-16 in the smears of women with mild and moderate dyskaryosis

The aim of this study was to examine the efficacy of semi-quantitative polymerase chain reaction (PCR) testing in cervical smears as an adjunct to cytological surveillance in a cohort of women with mild or moderate dyskaryosis. The study population comprised a group of 62 women who underwent twelve months of cytological and colposcopic surveillance as part of a larger randomised prospective study of women with mild and moderate dyskaryosis. Semi-quantitative PCR for HPV-16 DNA was carried out on the initial and twelve month study smears before a large loop excision of the transformation zone (LLETZ) was carried out. Smears from a control population which comprised 167 women without a history of abnormal cervical cytology who were attending family planning and general practitioner clinics for routine cervical smears were tested similarly. The presence of high or intermediate levels of HPV-16 DNA on both the initial and twelve month study smear was positively associated with the identification of cervical intraepithelial neoplasia (CIN) grades II or III in the LLETZ specimen (P = 0.01). While the combination of HPV-16 DNA testing with cytology on a repeat cervical smear improved the selection of women with underlying CIN II/III, there was still a false negative rate of 53%. Twenty-nine women had 'low risk' levels of HPV-16 DNA and mild dyskaryosis or less on both repeat smears indicating suitability for surveillance, but in fact 34% of them had CIN II/III. This study supports the finding reported previously of an association between high and intermediate levels of HPV-16 DNA and CIN II/III.(ABSTRACT TRUNCATED AT 250 WORDS)