Inactivation of HIV in blood

Developing pathogen reduction technologies for RBC suspensions

Numerous studies have evaluated a wide variety of photosensitizers and alkylating agents as candidates for a pathogen reduction process to be used in RBC suspensions. The methodologies that produce robust inactivation of pathogens with maintenance of RBC properties during storage involve those that specifically target nucleic acids. This has been demonstrated through in vitro studies by flexible photosensitizers, which specifically target nucleic acid but do not engage in photochemistry when free in solution and nucleic acid alkylating agents in conjunction with extracellular quencher(s) to protect against RBC membrane alkylation. The flexible photosensitizer method must be scaled up to entire units, and toxicology studies would need to be performed for further development. Clinical trials will ultimately be necessary to further develop either flexible photosensitizers or nucleic acid alkylating methods with quenchers for use in Transfusion Medicine.

Deactivation of human immunodeficiency virus type 1 in medium by copper oxide-containing filters

Human immunodeficiency virus type 1 (HIV-1) can be transmitted through breast-feeding and through contaminated blood donations. Copper has potent biocidal properties and has been found to inactivate HIV-1 infectivity. The objective of this study was to determine the capacity of copper-based filters to inactivate HIV-1 in culture media. Medium spiked with high titers of HIV-1 was exposed to copper oxide powder or copper oxide-impregnated fibers or passed through copper-based filters, and the infectious viral titers before and after treatment were determined. Cell-free and cell-associated HIV-1 infectivity was inhibited when exposed to copper oxide in a dose-dependent manner, without cytotoxicity at the active antiviral copper concentrations. Similar dose-dependent inhibition occurred when HIV-1 was exposed to copper-impregnated fibers. Filtration of HIV-1 through filters containing the copper powder or copper-impregnated fibers resulted in viral deactivation of all 12 wild-type or drug-resistant laboratory or clinical, macrophage-tropic and T-cell-tropic, clade A, B, or C, HIV-1 isolates tested. Viral inactivation was not strain specific. Thus, a novel means to inactivate HIV-1 in medium has been developed. This inexpensive methodology may significantly reduce HIV-1 transmission from "mother to child" and/or through blood donations if proven to be effective in breast milk or plasma and safe for use. The successful application of this technology may impact HIV-1 transmission, especially in developing countries where HIV-1 is rampant.

Pathogen inactivation: the definitive safeguard for the blood supply

CONTEXT

Pathogen inactivation provides a proactive approach to cleansing the blood supply. In the plasma fractionation and manufacturing industry, pathogen inactivation technologies have been successfully implemented resulting in no transmission of human immunodeficiency, hepatitis C, or hepatitis B viruses by US-licensed plasma derivatives since 1985. However, these technologies cannot be used to pathogen inactivate cellular blood components. Although current blood donor screening and disease testing has drastically reduced the incidence of transfusion-transmitted diseases, there still looms the threat to the blood supply of a new or reemerging pathogen. Of particular concern is the silent emergence of a new agent with a prolonged latent period in which asymptomatic infected carriers would donate and spread infection.

OBJECTIVE

To review and summarize the principles, challenges, achievements, prospective technologies, and future goals of pathogen inactivation of the blood supply.

DATA SOURCES

The current published English-language literature from 1968 through 2006 and a historical landmark article from 1943 are integrated into a review of this subject.

CONCLUSIONS

The ultimate goal of pathogen inactivation is to maximally reduce the transmission of potential pathogens without significantly compromising the therapeutic efficacy of the cellular and protein constituents of blood. This must be accomplished without introducing toxicities into the blood supply and without causing neoantigen formation and subsequent antibody production. Several promising pathogen inactivation technologies are being developed and clinically tested, and others are currently in use. Pathogen inactivation offers additional layers of protection from infectious agents that threaten the blood supply and has the potential to impact the safety of blood transfusions worldwide.

Development of models and detection methods for different forms of cytomegalovirus for the evaluation of viral inactivation agents

BACKGROUND

Cytomegalovirus (CMV) is transmitted by transfusion of infected blood products and can cause serious diseases in specific risk groups. CMV can be present in infected blood as cell-free virus (CFV), cell-associated actively replicating virus (CAV), and cell-associated latent virus (LV).

STUDY DESIGN AND METHODS

In vitro models for all three infectious forms of CMV and virus detection assays based on both tissue culture and polymerase chain reaction (PCR) were developed. The utility of the CMV model systems and assays were tested by validation studies of a novel pathogen inactivation agent, PEN110, for red blood cells.

RESULTS

Reproducible high titers of CFV and CAV were obtained by optimized tissue culture techniques for CMV-infected MRC-5 cells. An LV model was obtained with CMV-infected THP-1 cells and reactivation of virus replication by phorbol ester treatment. The model systems showed that PEN110 treatment is effective against all three forms of CMV as measured by tissue culture-based infectivity assays and a long-range PCR method specific for detection of damage to CMV viral DNA.

CONCLUSION

This study describes model systems to the relevant forms of CMV in blood and detection assays that can be used to evaluate the efficacy of viral inactivation agents.

Pathogen inactivation techniques

The desire to rid the blood supply of pathogens of all types has led to the development of many technologies aimed at the same goal--eradication of the pathogen(s) without harming the blood cells or generating toxic chemical agents. This is a very ambitious goal, and one that has yet to be achieved. One approach is to shun the 'one size fits all' concept and to target pathogen-reduction agents at the Individual component types. This permits the development of technologies that might be compatible with, for example, plasma products but that would be cytocidal and thus incompatible with platelet concentrates or red blood cell units. The technologies to be discussed include solvent detergent and methylene blue treatments--designed to inactivate plasma components and derivatives; psoralens (S-59--amotosalen) designed to pathogen-reduce units of platelets; and two products aimed at red blood cells, S-303 (a Frale--frangible anchor-linker effector compound) and Inactine (a binary ethyleneimine). A final pathogen-reduction material that might actually allow one material to inactivate all three blood components--riboflavin (vitamin B2)--is also under development. The sites of action of the amotosalen (S-59), the S-303 Frale, Inactine, and riboflavin are all localized in the nucleic acid part of the pathogen. Solvent detergent materials act by dissolving the plasma envelope, thus compromising the integrity of the pathogen membrane and rendering it non-infectious. By disrupting the pathogen's ability to replicate or survive, its infectivity is removed. The degree to which bacteria and viruses are affected by a particular pathogen-reducing technology relates to its Gram-positive or Gram-negative status, to the sporulation characteristics for bacteria, and the presence of lipid or protein envelopes for viruses. Concerns related to photoproducts and other breakdown products of these technologies remain, and the toxicology of pathogen-reduction treatments is a major ongoing area of investigation. Clearly, regulatory agencies have a major role to play in the evaluation of these new technologies. This chapter will cover the several types of pathogen-reduction systems, mechanisms of action, the inactivation efficacy for specific types of pathogens, toxicology of the various systems and the published research and clinical trial data supporting their potential usefulness. Due to the nature of the field, pathogen reduction is a work in progress and this review should be considered as a snapshot in time rather than a clear picture of what the future will bring.

Protecting the blood supply from emerging pathogens: the role of pathogen inactivation

Although the risk of infection by blood transfusion is relatively low, breakthrough infections still occur, Transfusion-related fatalities caused by infections continue to be reported, and blood is not tested for many potentially dangerous pathogens. The current paradigm for increasing the safety of the blood supply is the development and implementation of laboratory screening methods and restrictive donor criteria. When considering the large number of known pathogens and the fact that pathogens continue to emerge, it is clear that the utility of new tests and donor restrictions will continue to be a challenge when considering the cost of developing and implementing new screening assays, the loss of potential donors, and the risk of testing errors. Despite improving the safety of blood components, testing remains a reactive approach to blood safety. The contaminating organisms must be identified before sensitive tests can be developed. In contrast, pathogen inactivation is a proactive strategy designed to inactivate a pathogen before it enters the blood supply. Almost all pathogen inactivation technologies target nucleic acids, allowing for the inactivation of a variety of nucleic acid-containing pathogens within plasma, platelets, or red blood cells thus providing the potential to reduce transfusion-transmitted diseases. However, widespread use of a pathogen inactivation technology can only be realized when proven safe and efficacious and not cost-prohibitive.

Erythrocytes-the 'house elves' of photodynamic therapy

Photodynamic therapy (PDT) and fluorescence diagnosis (FD) are being developed for a number of clinical applications. Since fluorophores and photosensitising drugs are usually given systemically their effect on blood elements are of significant importance. Photodynamic effects on erythrocytes occur naturally in patients with erythropoietic protoporphyria (EPP). Exposure to small fluences, as obtained by the erythrocytes when they pass capillaries in the skin, leads to transfer of the photosensitiser protoporphyrin IX (PP IX), from EPP erythrocytes to endothelial cells. Thus, the erythrocytes are partly protected while the endothelial cells suffer photodamage. During photodynamic therapy in vivo erythrocytes are regularly photosensitised. This side effect is partly intended but mostly unwanted, and a summary of this topic is given. Furthermore, the effect of UV-A on erythrocytes that is accompanied with the formation of bilirubin is reviewed. Erythrocytes serve as convenient model cells for experimental research. Such use of erythrocytes to screen new photosensitisers may be of limited value. A combination of photohaemolysis and haemoglobin oxygenation may become the basis for an assay for in vitro phototoxicity. Erythrocytes from birds are good model cells for exploration of physiological and molecular mechanisms involved in PDT. A potential mechanism of PDT induced behaviour resembling apoptosis in erythrocytes is provided.PDT for sterilisation of erythrocyte concentrates has a potential for medical use. Photodynamic effects on the erythrocytes themselves should be avoided. This is realised by choosing a virus-selective photosensitiser, low fluences and treatment of the concentrates with agents like dipyridamole and antioxidants. Future aspects of applications of photosensitisation of red blood cells are discussed.

Induction of latent human cytomegalovirus by conventional gamma irradiation and prevention by treatment with INACTINE PEN110

BACKGROUND AND OBJECTIVES

Two different leucocyte-inactivation technologies--gamma irradiation and INACTINE PEN110--were evaluated for their effects on cell-associated human cytomegalovirus (CMV).

MATERIALS AND METHODS

In vitro CMV-infected cells were spiked into leucoreduced red blood cell concentrates (RCC) or medium at a final concentration of 0.5 - 1 x 10(7) cells/ml to mimic non-leucoreduced levels of leucocytes. The spiked RCC/medium was divided into three equal units and treated with gamma irradiation at the US Food and Drug Administration (FDA)-approved dose of 25 Gy, with 0.1% v/v PEN110 at 22 degrees C for 24 h, or stored at 4 degrees C as a control. The treated and control cells were recovered and tested using infectivity, viability and polymerase chain reaction (PCR) assays.

RESULTS

Gamma-irradiated CMV-infected cells produced active virus, as shown by both infectivity assays and PCR quantification of viral DNA. PCR analysis demonstrated higher CMV DNA levels in gamma-irradiated, latently infected monocytic THP-1 cells than untreated control cells. The increased virus production in gamma-irradiated cells was paralleled by an increased metabolic rate and the development of enlarged multinuclear cells. In contrast, PEN110 treatment terminated virus replication and completely inactivated the infected cell.

CONCLUSIONS

These results demonstrate that gamma irradiation, at levels currently used to treat RCC, has the capacity to induce expression of CMV, whereas PEN110 inhibits CMV replication and efficiently inactivates the infected cells.

Inactivation of protozoan parasites in red blood cells using INACTINE PEN110 chemistry

BACKGROUND

The transmission of parasites, including Babesia, plasmodia, and Trypanosoma cruzi, via transfusions is an important public health concern. INACTINE technology is a pathogen-reduction process that utilizes PEN110, an electrophilic agent that inac-tivates a wide range of pathogens by disrupting nucleic acid replication. The present study investigated the effect of PEN110 treatment on the viability of protozoa in RBCs.

STUDY DESIGN AND METHODS

B. microti-parasitized RBCs from infected hamsters were treated with PEN110 and inoculated to naïve animals. Parasitemia was detected by blood smears and PCR. Human RBCs infected with P. falciparum were treated with PEN110 and incubated with fresh RBCs. P. falciparum multiplication was detected by blood smears. Human RBCs spiked with T. cruzi and treated with PEN110 were analyzed for the presence of live parasites using in-vitro infectivity assay or by inoculating susceptible mice.

RESULTS

Treatment of RBCs infected with B. microti or P. falciparum with 0.01 to 0.1 percent (vol/vol) PEN110 resulted in parasite inactivation to below the limit of detection during 24 hours. T. cruzi inoculated into human RBCs was inactivated below the limit of detection by 0.1 percent PEN110 after 3 hours.

CONCLUSION

The study demonstrates that treatment of blood with PEN110 is highly effective in eradicating transfusion-transmitted protozoan parasites.

Development of a sensitive PCR inhibition method to demonstrate HBV nucleic acid inactivation

BACKGROUND

The evaluation of pathogen reduction technologies with relevant viruses currently contaminating the blood supply is limited by the availability of high-titer virus inocula and sensitive in vitro or in vivo infectivity assays. Because HBV infectivity can only be assessed by in vivo studies with chimpanzees, a sensitive PCR inhibition assay was developed to measure PEN110 inactivation of HBV.

STUDY DESIGN AND METHODS

PCR amplification of 1.1 kb of HBV genome was optimized to determine DNA damage introduced by treatment with PEN110 in RBCs. Inactivation of duck HBV (DHBV) in RBCs, with measurement of the in vitro infectivity, was performed to validate the PCR assay.

RESULTS

The PCR was highly specific and sensitive for amplification of the HBV genome and used to demonstrate a reduction of at least 7.2 and 8.1 log geq per mL within the first 18 hours of PEN110 treatment. PEN110 inactivation of DHBV was also achieved within the first 18 hours with a reduction factor of at least 5.0 log tissue culture infectious dose 50 percent per mL, suggesting that PCR inhibition is an alternative to infectivity assays.

CONCLUSION

This study establishes PCR inhibition as a reasonable approach to assess the efficiency of PEN110 inactivation of human pathogens with human plasma donations that have been found to contain high titers of relevant agents during different stages of infection.

Inactivation of mycoplasma species in blood by INACTINE PEN110 process

BACKGROUND

Mycoplasmas have been associated with multiple acute and chronic diseases. Mycoplasma genome is found in the blood of 10 to 15 percent of subjectively healthy individuals. If blood borne and viable in donated blood, mycoplasmas could potentially be transfusion transmissible. The INACTINE PEN110 technology is a pathogen reduction process that is in Phase 3 clinical studies. The present study investigated the ability of this process to eradicate mycoplasmas in human blood.

STUDY DESIGN AND METHODS

Identical whole blood or RBC units inoculated with Mycoplasma arthritidis or M. pneumoniae were incubated with PEN110 (inactivating agent) for 24 hours at 23 degrees C. Sham controls were treated with buffer under the same conditions. 4 degrees C controls were put on storage immediately after the spike.

RESULTS

No viable microorganisms were detected in PEN110-treated units after 24 hours of incubation. Sham controls showed no changes to mycoplasma titers during the incubation. In 4 degrees C controls, minor decrease of mycoplasma titers was observed during the storage.

CONCLUSION

The INACTINE process inactivates more than 107 mycoplasma CFU per mL in whole blood and RBCs. This study is the first demonstration of susceptibility of mycoplasmas to pathogen reduction. The data provide further support for the ability of INACTINE technology to address microbial safety issues that are not well characterized.

Pathogen inactivation of RBCs: PEN110 reproductive toxicology studies

BACKGROUND

The novel PEN110 chemistry (INACTINE, V.I. Technologies) process for the purification of blood for transfusions involves treating WBC-reduced RBCs with PEN110 to inactivate a wide spectrum of pathogens. The washed RBC preparation has a residual PEN110 level of less than 0.00005 mg per mL. It is important to verify that the trace amounts of residual PEN110 in blood prepared for transfusions will not produce adverse effects on reproduction, fertility, or fetal development.

STUDY DESIGN AND METHODS

A fertility and early embryonic development study was conducted in male and female Sprague-Dawley rats at IV doses of up to 0.5 mg PEN110 per kg of body weight following standard regulatory protocols. A fetal developmental study was conducted in Hra:(NZW)SPF pregnant rabbits at IV doses of up to 1.0 mg per kg of body weight following standard regulatory protocols. In both cases the highest dose was shown to be a maximum tolerated dose in pregnant animals based on body weight gain during pregnancy.

RESULTS

In the fertility and early embryonic development study, no treatment-related effects were noted on estrous cycles, pregnancy rate, implantation sites, corpora lutea, number of resorptions, and live embryos in female rats or sperm motility, sperm morphology, and sperm counts in male rats. In the fetal developmental study, PEN110 had no effect on embryofetal viability and growth. This is consistent with other data indicating that PEN110 is rapidly cleared by urinary excretion. On a mg per kg of body weight dose basis, the no-observed-effect level doses for rats in the fertility study and rabbits in the developmental study were 2,000 and 4,000 (320 and 1,300 scaled to dose per unit body surface area [DBSA]) times that which a person would receive given 1 unit of treated blood. Considering the cumulative animal dosages, the safety factor values increase to 48,000- and 60,000-fold (7,700 and 19,400 scaled to dose per unit body surface area).

CONCLUSION

These results indicate that the trace amount of residual PEN110 in the purified blood component is well below the level that could present a risk of reproductive toxicity to the patient.

West Nile virus in blood: stability, distribution, and susceptibility to PEN110 inactivation

BACKGROUND

The outbreak of West Nile virus (WNV) is the most recent reminder that the blood supply continues to be vulnerable to emerging and reemerging pathogens. A potentially prospective approach to reducing the risk of transfusion-transmitted infections of a known or newly emerging microbe is implementation of a broad-spectrum pathogen reduction technology. The purpose of this study was to evaluate the susceptibility of WNV to PEN110 inactivation in RBCs and to characterize the WNV interaction with blood, including the stability of WNV in RBCs stored at 1 to 6 degrees C, its distribution and infectivity, and its ability to infect WBCs.

STUDY DESIGN AND METHODS

Inactivation was performed with three WNV isolates spiked into WBC-reduced RBCs. The stability of the virus was evaluated by spiking two viral loads into RBCs followed by storing at 1 to 6 degrees C for up to 42 days. The distribution of the virus in plasma, RBCs, and PBMCs was evaluated with whole blood from infected hamsters. Finally, in vitro propagation of WNV was evaluated with the THP-1 cell line and primary monocytes.

RESULTS

The kinetics of PEN110 inactivation of WNV isolates RI-44, NJ-176, and 99-3494031 were fast and complete within 24 hours with reduction factors of 5 to 7 log plaque-forming units per mL. WNV remained infectious for up to 42 days at 1 to 6 degrees C. The WNV titers in whole blood, plasma, RBCs, and PBMC fractions were equally distributed and ranged from 2 to 3 log tissue culture infectious dose 50 percent per mL. Productive infection of stimulated monocytes and THP-1 cells was also demonstrated.

CONCLUSIONS

These studies demonstrated that PEN110 efficiently inactivated WNV in RBCs and whole blood from infected hamsters to the limit of detection. WNV survived in RBCs stored at 1 to 6 degrees C with a gradual loss of titer but infectivity could still be observed for up to 42 days. In addition, it was observed that WNV was equally distributed in all blood fractions including PBMCs and it was possible to establish productive infection of a human monocytic cell line and stimulated human monocytes.

Safety of the blood supply: role of pathogen reduction

Even though the blood supply is very safe, the risk of transfusion transmitted disease is not zero. To improve the safety of the blood supply, pathogen reduction (PR) technology has been developed. The principle of most current PR strategies involves modifying DNA or RNA templates and making them inaccessible to DNA or RNA polymerase. Several platforms of pathogen reduction are available including psoralens, alkylating compounds, binary ethyleneimine-like compounds, riboflavin, methylene blue, and solvent-detergent treatment. PR systems have been designed for RBC, plasma, and platelets. PR technology has been found to be effective for a variety of pathogens including lipid-enveloped and non-enveloped viruses, bacteria and parasites. Pre-clinical studies and Phase III clinical trials to evaluate the efficacy and safety of these PR technologies are currently ongoing.

Prevention of Yersinia enterocolitica, Pseudomonas fluorescens, and Pseudomonas putida outgrowth in deliberately inoculated blood by a novel pathogen-reduction process

BACKGROUND

Yersinia enterocolitica, Pseudomonas fluorescens, and P. putida are responsible for a significant amount of the bacterial sepsis cases attributed to RBC transfusions. INACTINE is a pathogen-reduction process for RBCs, which consists of incubation of RBCs with PEN110 (proprietary compound) followed by automated washing of the RBCs. INACTINE is an electrophilic agent, which inactivates a wide range of viruses and WBCs by disruption of nucleic acid replication. The present study investigated the effect of the PEN110 process on Y. enterocolitica, P. fluorescens, and P. putida.

STUDY DESIGN AND METHODS

Identical units of reduced CPD/ADSOL additive solution (AS-1) or CP2D/Nutricel additive solution (AS-3) RBCs were inoculated with 10 to 100 CFU per mL of either Y. enterocolitica, P. fluorescens, or P. putida. The control units were put on storage immediately after the bacterial spike. The test units were subjected to the PEN110 process and then stored. Sham control units were processed the same way as test units without addition of PEN110. Bacterial titer in all units was monitored during the 6-week storage period.

RESULTS

No bacteria were detected in any of the RBC units (n = 9 for each microorganism) prepared using the PEN110 process throughout 6 weeks of storage. Substantial bacterial growth occurred in all control and in a majority of sham control units (11 out of 15 experiments). The bacterial inactivation by the INACTINE process was found to be equally effective in CPD/AS-1 and CP2D/AS-3 RBC units.

CONCLUSION

The INACTINE process effectively prevented the outgrowth of Y. enterocolitica, P. fluorescens, and P. putida deliberately inoculated into WBC-reduced CPD/AS-1 and CP2D/AS-3 RBCs. The results demonstrated the crucial bactericidal role of PEN110 in the INACTINE process.

Broad-spectrum virus reduction in red cell concentrates using INACTINE PEN110 chemistry

BACKGROUND AND OBJECTIVES

The risk of transmission of blood-borne pathogens by transfusion is a persistent problem in medicine. To address this safety issue, INACTINE PEN110 chemistry is being utilized to develop a process for preparing pathogen-reduced red blood cell concentrates (RBCC). The purpose of this study was to characterize the virucidal effectiveness of the INACTINE PEN110 chemistry in full units of RBCC by using a panel of viruses with diverse properties in composition, size and shape.

MATERIALS AND METHODS

The panel included four enveloped (bovine viral diarrhoea virus, pseudorabies virus, vesicular stomatitis Indiana virus and sindbis virus), six non-enveloped (porcine parvovirus, human adenovirus 2, reovirus 3, vesicular exanthema of swine virus, bluetongue virus, and foot and mouth disease virus) and cell-associated (human immunodeficiency) viruses. All viruses were individually spiked into CPD/AS-1, CP2D/AS-3 and CPD/AS-5 RBCC units and treated with 0.1% PEN110 (vol/vol) at 22 +/- 2 degrees C for up to 22 +/- 2 h. The PEN110 treatment reaction was stopped by chemical quenching, and residual virus was assayed. The cytotoxicity effect of PEN110-treated RBCC on indicator cells and the potential interference with the ability of the virus to infect indicator cells was determined and taken into consideration for calculating the virus-reduction factors, to avoid underestimation or overestimation of the virus reduction.

RESULTS

The kinetics of inactivation for viruses spiked into CPD/AS-1, CP2D/AS-3 and CPD/AS-5 RBCC were equivalent. All viruses analysed in this study were reduced to the limit of detection of the assay. The reduction factors for the virus panel ranged from 4.2 to 7.5 log10/ml.

CONCLUSIONS

The results from the study demonstrate for the first time that a pathogen-reduction technology for RBCC can achieve a broad-spectrum virucidal effect against both enveloped and non-enveloped viruses. The broad spectrum of virucidal activity of INACTINE PEN110, and equivalent kinetics of virus inactivation in RBCC prepared using different commercially available RBC storage solutions, demonstrate the robustness of this pathogen-reduction process.