Quantitation of herpes simplex viral DNA in Vero cells for evaluation of an antiviral agent using the polymerase chain reaction

Polyoxometalates active against tumors, viruses, and bacteria

Polyoxometalates (PMs) as discrete metal-oxide cluster anions with high solubility in water and photochemically and electrochemically active property have a wide variety of structures not only in molecular size from sub-nano to sub-micrometers with a various combination of metals but also in symmetry and highly negative charge. One of the reasons for such a structural variety originates from their conformation change (due to the condensed aggregation and the structural assembly) which strongly depends on environmental parameters such as solution pH, concentration, and coexistent foreign inorganic and/or organic substances. In the course of the application of the physicochemical properties of such PMs to the medical fields, antitumoral, antiviral, and antibacterial activities have been developed for realization of a novel inorganic medicine which provides a biologically excellent activity never replaced by other approved medicines. Several PMs as a candidate for clinical uses have been licensed toward the chemotherapy of solid tumors (such as human gastric cancer and pancreatic cancer), DNA and RNA viruses (such as HSV, HIV, influenza, and SARS), and drug-resistant bacteria (such as MRSA and VRSA) in recent years: [NH3Pr(i)]6[Mo7O24]∙3H2O (PM-8) and [Me3NH]6[H2Mo(V) 12O28(OH)12(Mo(VI)O3)4]∙2H2O (PM-17) for solid tumors; K7[PTi2W10O40]∙6H2O (PM-19), [Pr(i)NH3]6H[PTi2W10O38(O2)2]∙H2O (PM-523), and K11H[(VO)3(SbW9O33)2]∙27H2O (PM-1002) for viruses; and K6[P2W18O62]∙14H2O (PM-27), K4[SiMo12O40]∙3H2O (SiMo12), and PM-19 for MRSA and VRSA. The results are discussed from a point of view of the chemotherapeutic clarification in this review.

Prevention of the interaction between HVEM, herpes virus entry mediator, and gD, HSV envelope protein, by a Keggin polyoxotungstate, PM-19

One of the Keggin-type heteropolyoxotungstates (K7[PTi2W10O40]6H2O:PM-19) is a potent inhibitor of the replication of herpes simplex virus (HSV) both standard strain 169 and the thymidine kinase-defective strain YS-4C-1 in vitro and in vivo. HSV envelope protein, gD, is necessary for virus entry into the cells. Some cellular molecules, such as HVEM, were reported to act as cofactors during the viral entry step. We determined whether PM-19 prevents these interactions between HSV-gD and HVEM. These activities were investigated using the Ciphergen and BIACORE system. Using a protein chip, many kinds of gD-specific binding proteins were captured, but these proteins could not be identified. Several proteins in these gD-binding proteins were inhibited its interaction with gD due to the presence of PM-19. Using the BIACORE system, the affinity of PM-19 to gD was low, because PM-19 has no direct inactivation activity against the virion. The specific binding of HVEM to the gD was shown as KD of 1.1e-9. The affinity of PM-19 for HVEM was high (KD:2e-9). To determine the competitive binding, the PM-19 (10 microg/ml) and several concentrations of HVEM solution mixtures were injected over the gD-fixed sensor surface. Each binding signal was stable in the range of approximately 270-300 RU. In the case of the addition of PM-19 to HVEM solution, the binding signals were elevated by PM-19 dose dependently. These results suggest that the bindings of PM-19 to gD are not disturbed by the presence of HVEM. PM-19 prevents the interaction between HVEM and gD.

Occult herpes family viral infections are endemic in critically ill surgical patients

OBJECTIVE

Herpes family viruses have been recognized as pathogens for many years in immunosuppressed transplant or human immunodeficiency virus patients, but they have garnered little attention as potential pathogens in the nonimmunosuppressed critically ill. The objective of this study was to define the prevalence of and risk factors for development of herpes family virus infection in chronic critically ill surgical patients.

DESIGN

Prospective epidemiologic study.

SETTING

A 38-bed surgical intensive care unit in a major university hospital.

PATIENTS

Nonimmunosuppressed intensive care unit patients in intensive care unit for >/=5 days.

INTERVENTIONS

None; patients received no antiviral treatment during the study.

MEASUREMENTS AND MAIN RESULTS

Weekly cultures for cytomegalovirus (CMV) and herpes simplex virus, viral serologies, and T-cell counts were performed. The prevalence (95% confidence interval) of positive respiratory cultures for herpes simplex or CMV was 35% (22-49%); 15% (5-25%) cultured positive for CMV, 23% (11-35%) cultured positive for herpes simplex virus, and one patient's respiratory secretions culturing positive for both CMV and herpes simplex virus. The prevalence of CMV viremia was only 5.8% (1-10%). CMV+ patients had longer hospital admissions, intensive care unit admissions, and periods of ventilator dependence than CMV- patients, despite having comparable severity of illness scores. CMV+ patients also had significantly higher numbers of blood transfusions, prevalence of steroid exposure, and prevalence of hepatic dysfunction, and all were immunoglobulin G positive at the beginning of the study. In contrast, herpes simplex virus-positive patients had lengths of hospital admissions, lengths of intensive care unit admissions, and periods of ventilator dependence comparable with patients without viral infections (p >.05).

CONCLUSIONS

There is a significant prevalence (22-49%) of occult active herpes family viruses in chronic critically ill surgical patients. The clinical significance of these viral infections is unknown, although CMV+ patients have significantly higher morbidity rates than CMV- patients. Several factors suggest pathogenicity, but further study is needed to define causality.

Mechanism of the protective effect of heteropolyoxotungstate against herpes simplex virus type 2

The effects of heteropolyoxotungstate (K(7)[PTi(2)W(10)O(40)]. 6H(2)O; PM-19) on the replication of herpes simplex virus type 2 (HSV-2) were examined using a semiquantitative polymerase chain reaction of intracellular viral DNA established by us and also other methods. Vero cells were infected with HSV-2 strains: either the standard strain 169, or the acyclovir-resistant strain YS-4C-1. PM-19 was added at various stages during the replication of HSV-2. PM-19 strongly inhibited the synthesis of viral genomic DNA when it was added at the time of infection. The addition of PM-19 60-90 min after viral inoculation time-dependently decreased the antiviral activity and increased the relative yield of viral DNA, and the addition of PM-19 was completely ineffective at times later than 90 min. These results suggested that PM-19 inhibited viral penetration but did not affect the synthesis of viral DNA. Furthermore, PM-19 strongly inhibited a second round of infection.

The memory effect of heteropolyoxotungstate (PM-19) pretreatment on infection by herpes simplex virus at the penetration stage

The keggin-type heteropolyoxotungstate K(7)[PTi(2)W(10)O(40)].6H(2)O (PM-19) is a potent polyoxometalate (PM) inhibitor of the replication of herpes simplex virus (HSV). Pretreatment of Vero cells with PM-19 prior to HSV-2 infection enhanced the antiviral potency of PM-19 almost 10-fold compared with treatment of the cells only after infection. The pretreatment effect of PM-19 is called "the memory effect". The memory effect was reflected by inhibition of plaque formation and decrease of intracellular virus DNA quantity, and was strongest when PM-19 was present during the penetration stage of HSV-2 infection. The effect was maintained under conditions of fusion induced by polyethyleneglycol treatment. This suggests that PM-19 does not act at the fusion stage of infection. Using the infectious center assay method, it was clarified that a second round of infection was inhibited by about 30% in the presence of PM-19 at the penetration stage compared with the virus control in nontreated cells. The inhibition was enhanced to about 60% by PM-19 pretreatment prior to infection. This suggests that PM-19 pretreatment of the cells protects them against HSV-2 infection.

HSV-2 disrupts gap junctional intercellular communication between mammalian cells in vitro

Infection by herpes simplex virus-2 (HSV-2) disrupts both dye and electrical coupling in Vero (African green monkey kidney) cell cultures. Vero cells in vitro were iontophoretically injected with the fluorescent dye Lucifer yellow CH, the spread of which revealed that cells throughout the confluent sheet shared open gap junctions. However, 24 h after infection with the virus (but before cells became rounded), dye always remained only within the target cell. Intracellular electrophysiological measurements of ionic coupling revealed a 0.4 coupling coefficient for adjacent cells in uninfected control cultures. By 3 h following infection significant down-regulation of gap junctions had begun, preceding by many hours any signs of infection visible with the light microscope. Measurements between adjacent cells 3 h post-infection, a period when HSV-2 gene expression is known to be at a maximum, yielded an average coupling coefficient of 0.35. By 6 h post-infection (a period of known viral DNA replication) average coupling coefficient for adjacent cells was 0.25, while by 24 h post-infection the average fill still further to <0.08. A coupling coefficient of <0.08 suggests that infection by HSV-2 completely disabled the gap junctions.