Acyclic nucleoside phosphonates: a key class of antiviral drugs

Almost 20 years after the broad antiviral activity spectrum of the first acyclic nucleoside phosphonates was described, several of these compounds have become important therapies for DNA virus and retrovirus infections. Here, we review the discovery and development of acyclic nucleoside phosphonates, focusing on cidofovir and its potential in the treatment of various herpes-, papilloma-, polyoma-, adeno- and pox-virus infections, adefovir for the treatment of hepatitis B and tenofovir for the treatment of AIDS and the prevention of HIV infections.

Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections: cidofovir against herpesvirus (herpes simplex virus types 1 and 2 varicella-zoster virus, cytomegalovirus [CMV], Epstein-Barr virus, and human herpesviruses 6, 7, and 8), polyomavirus, papillomavirus, adenovirus, and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus, and orf virus) infections; adefovir against herpesvirus, hepadnavirus (human hepatitis B virus), and retrovirus (human immunodeficiency virus types 1 [HIV-1] and 2 [HIV-2], simian immunodeficiency virus, and feline immunodeficiency virus) infections; and tenofovir against both hepadnavirus and retrovirus infections. Cidofovir (Vistide) has been officially approved for the treatment of CMV retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) has been approved for the treatment of HIV infections (i.e., AIDS), and adefovir dipivoxil (Hepsera) has been approved for the treatment of chronic hepatitis B. Nephrotoxicity is the dose-limiting side effect for cidofovir (Vistide) when used intravenously (5 mg/kg); no toxic side effects have been described for adefovir dipivoxil and tenofovir disoproxil fumarate, at the approved doses (Hepsera at 10 mg orally daily and Viread at 300 mg orally daily).

Phosphonomethoxyalkyl analogs of nucleotides

Acyclic nucleoside phosphonates (ANP) are analogs of nucleotides exhibiting various biological (e.g. antiviral, cytostatic, antiparasitic, immunomodulatory) activities. This review describes synthetic approaches to their preparation, biological activities, structure-activity relationships and mode of action of ANPs, with emphasis to selected drugs or drug candidates. Three compounds of the ANP group (cidofovir, adefovir, tenofovir) are active components of potent antivirals approved for therapeutic use in human medicine aimed at hepatitis B, AIDS and various diseases caused by DNA viruses.

Effect of probiotics enriched diet on Paralichthys olivaceus infected with lymphocystis disease virus (LCDV)

We report the effect of two probiotics, Lactobacil and Sporolac as separate or mixed diets on innate immune mechanisms, such as phagocytosis activity, superoxide anion production of blood leukocytes, complement activity and plasma lysozyme activity, and disease resistance in lymphocystis disease virus (LCDV) infected olive flounder, Paralichthys olivaceus (523.5 +/- 18.3 g) on week 1, 2, and 4. In infected fish, administration of diet supplemented with Lactobacil individually or mixed with Sporolac significantly enhanced the immune parameters like phagocytic activity superoxide anion production, complement activity, and plasma lysozyme. However administration of supplemented diet with Sporolac alone, all the chosen immune parameters did not enhance when compared to control group; this diets resulted in lower mortality (30% and 25%) than Sporolac diet group (45%) in 30 days. We conclude that Lactobacil individually or mixed with Sporolac act as immunostimulants that enhance the innate immune response and disease resistance in lymphocystis disease virus (LCDV) infected olive flounder.

Update on new antivirals under development for the treatment of double-stranded DNA virus infections

All the currently available antiviral agents used in the treatment of double-stranded (ds) DNA viruses, with the exception of interferon-α, inhibit the same target, the viral DNA polymerase. With increasing reports of the development of resistance of herpes simplex virus (HSV), cytomegalovirus (CMV), and hepatitis B virus (HBV) to some of these drugs, new antiviral agents are needed to treat these infections. Additionally, no drugs have been approved to treat several DNA virus infections, including those caused by adenovirus, smallpox, molluscum contagiosum, and BK virus. We report the status of 10 new antiviral drugs for the treatment of dsDNA viruses. CMX-001 has broad activity against dsDNA viruses; 3 helicase-primase inhibitors, maribavir, and FV-100 have activity against certain herpesviruses; ST-246 inhibits poxviruses; GS-9191 inhibits papillomaviruses; and clevudine and emtricitabine are active against HBV. Most of these drugs have completed at least phase I trials in humans, and many are in additional clinical trials.

Antiviral acyclic nucleoside phosphonates structure activity studies

This review concerns acyclic nucleoside phosphonates (ANP) and describes the concept of the design of isopolar and isosteric nucleotide analogues resistant towards degradation by enzymes in vivo. It describes the development of research which led to the discovery of several structurally related potent antivirals and ultimately resulted in the development of drugs directed against HIV, HBV and DNA-virus infections in general, namely adefovir, cidofovir and tenofovir. In addition to these "classical compounds" the review describes the present development in the field of ANP, the "open-ring ANP" and discusses the present achievements, concept of prodrug design and application.

Potential of acyclic nucleoside phosphonates in the treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates [HPMPC: cidofovir, Vistide; PMEA: adefovir dipivoxil, Hepsera; and PMPA: tenofovir, Viread] have proven to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections, for example, cidofovir against herpesvirus [herpes simplex virus type 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpesvirus type 6, 7 and 8), polyoma-, papilloma-, adeno- and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus and orf) infections; adefovir against herpesvirus, hepadnavirus [human hepatitis B virus] and retrovirus [HIV type-1 and 2, simian immunodeficiency virus and feline immunodeficiency virus] infections; and tenofovir against both hepadna- and retrovirus infections. Cidofovir has been officially approved for the treatment of cytomegalovirus retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) for the treatment of HIV infections (i.e., AIDS) and adefovir dipivoxil for the treatment of chronic hepatitis B.

Acyclic nucleoside phosphonates in the chemotherapy of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates [HPMPC (cidofovir), PMEA (adefovir) and PMPA] have proved to the effective in vitro (cell culture systems) and in vivo (animal models, clinical studies) against a wide variety of DNA virus and retrovirus infections: i.e., HPMPC against herpesvirus (herpes simplex virus type 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpesvirus types 6, 7, and 18), polyoma-, papilloma-, adeno-, and poxvirus (vaccinia virus, molluscum contagiosum virus) infections; PMEA against herpesvirus, hepadnavirus (human hepatitis B virus) and retrovirus (human immunodeficiency virus type 1 and 2, simian immunodeficiency virus, and feline immunodeficiency virus) infections; and PMPA against both hepadna- and retrovirus infections.

Immunostimulatory activity of sulfated galactans isolated from the red seaweed Gracilaria fisheri and development of resistance against white spot syndrome virus (WSSV) in shrimp

Sulfated galactans (SG) were isolated from the red seaweed Gracilaria fisheri (G. fisheri). Chemical analysis revealed SG contains sulfate (12.7%) and total carbohydrate (42.2%) with an estimated molecular mass of 100 kDa. Structure analysis by NMR and FT-IR spectroscopy revealed that SG is a complex structure with a linear backbone of alternating 3-linked β-D-galactopyranose and 4-linked 3,6-anhydrogalactose units with partial 6-O-methylate-β-D-galactopyranose and with sulfation occurring on C4 of D-galactopyranose and C6 of L-galactopyranose units. SG treatment enhanced immune parameters including total haemocytes, phenoloxidase activity, superoxide anions and superoxide dismutase in shrimp Penaeus monodon. Shrimp fed with Artemia salina enriched with SG (100 and 200 μg ml(-1)) and inoculated with white spot syndrome virus (WSSV) showed a significantly lower mortality rate and lower viral VP 28 amplification and expression than control. The results suggest that SG from G. fisheri exhibits immune stimulatory and antiviral activities that could protect P. monodon from WSSV infection.

Effect of immune modulation on TT virus (TTV) and TTV-like-mini-virus (TLMV) viremia

The present study was designed to investigate how two chronically replicating viruses, TT virus (TTV) and TTV-like mini virus (TLMV), interact with host defence systems. Successive serum samples from three groups of subjects, undergoing modifications of their antiviral defence, were tested by real-time PCR to measure changes in viral titers, and by sequence analyses to indicate whether increases in viremia could be attributed to infection with an unfamiliar strain: 1) in patients receiving immunosuppressants subsequent to kidney transplantation, viral titers tended to increase; 2) in soldiers undergoing extreme training known to cause immunosuppression, insignificant increases in titers were observed; and 3) interferon treatment of patients with hepatitis C virus caused a temporary decrease in TTV and TLMV titers. Increases in viremia were associated only occasionally with the appearance of novel strains. The above results add to knowledge on how these viruses are influenced by the host.

The Antiviral Effects of Na,K-ATPase Inhibition: A Minireview

Since being first described more than 60 years ago, Na,K-ATPase has been extensively studied, while novel concepts about its structure, physiology, and biological roles continue to be elucidated. Cardiac glycosides not only inhibit the pump function of Na,K-ATPase but also activate intracellular signal transduction pathways, which are important in many biological processes. Recently, antiviral effects have been described as a novel feature of Na,K-ATPase inhibition with the use of cardiac glycosides. Cardiac glycosides have been reported to be effective against both DNA viruses such as cytomegalovirus and herpes simplex and RNA viruses such as influenza, chikungunya, coronavirus, and respiratory syncytial virus, among others. Consequently, cardiac glycosides have emerged as potential broad-spectrum antiviral drugs, with the great advantage of targeting cell host proteins, which help to minimize resistance to antiviral treatments, making them a very promising strategy against human viral infections. Here, we review the effect of cardiac glycosides on viral biology and the mechanisms by which these drugs impair the replication of this array of different viruses.

Imiquimod; an international update on therapeutic uses in dermatology

Imiquimod, the first member of a new class of immune response modifiers, is approved for the treatment of external genital and perianal warts. The clinical effect of imiquimod stems from cytokine-induced activation of the immune system. Topical application of imiquimod elevates the production of cytokines, including the principal cytokine for antiviral activity, interferon-alpha. This is the initial event in an immunological cascade resulting in the stimulation of the innate immune response as well as the cell-mediated pathway of acquired immunity. This immune modification mediates the indirect antiviral, antiproliferative and antitumor activity of imiquimod in vivo. These properties highlight the potential of imiquimod not only as an effective treatment for genital warts, but also as a treatment for other cutaneous viral infections and cutaneous neoplasms.

Ionic Contra-Viral Therapy (ICVT); a new approach to the treatment of DNA virus infections

The sequestration of cellular K(+) has been shown elsewhere to elicit a broad spectrum of antiviral activity. The obligatory, coupled cotransports of Na(+), K(+) and Cl(-) (NKCC1) and of Na(+) and K(+) (NKATPase) effect net cellular K(+) influx. We examined the effects of specific inhibitors of these transports; a cardiac glycoside (Digoxin) and a loop diuretic (Furosemide) on virus replication in vitro. The replication of the DNA viruses, herpes simplex virus, varicella zoster virus, human cytomegalovirus and adenovirus was inhibited. There was normal replication of the RNA virus encephalomyocarditis virus. Antiviral activities of both drugs were influenced by extracellular K(+). Antiviral effects were most potent when Digoxin and Furosemide were used in combination. Targeting the host cell in this way is fundamentally different to other antiviral drug developments to date and we propose the descriptive term Ionic Contra Viral Therapy (ICVT) for the purpose of definition. We believe that specific inhibitors of coupled K(+) transports merit controlled clinical trial for a broad spectrum of DNA virus infections by local application.

Effect of interferon on a nonenveloped DNA virus (TT virus) associated with acute and chronic hepatitis of unknown etiology

An unenveloped DNA virus named TT virus (TTV) has been reported in association with acute and chronic hepatitis of unknown etiology. The effect of interferon on TTV was evaluated in the patients with chronic hepatitis C who were coinfected with TTV. TTV DNA was determined by a polymerase chain reaction with heminested primers in the 96 patients with chronic hepatitis C who received interferon-alpha (516 million units in 26 weeks) and followed for 24 months thereafter. TTV DNA was detected in 31 (32%) patients before therapy. TTV DNA became undetectable during interferon therapy and remained absent in 14 (45% of the 31 patients) through 24 months thereafter. The four patients with pretreatment TTV DNA titer > or =10(3)/ml did not respond. These results indicate that TTV is sensitive to interferon, and the response would be inversely correlated with pretreatment viral titers.

SEN virus: response to interferon alfa and influence on the severity and treatment response of coexistent hepatitis C

The SEN virus (SENV) is a recently identified single-stranded, circular DNA virus. A strong association between 2 SENV variants (SENV-D and SENV-H) and transfusion-associated non-A-to-E hepatitis has been reported. To clarify the effect of SENV infection on coexisting chronic hepatitis C and the effect of interferon alfa (IFN-alpha) therapy on SENV replication, SENV DNA was quantitated by polymerase chain reaction in serum samples from 186 patients with chronic hepatitis C. Thirty-nine of 186 (21%) patients with chronic hepatitis C were positive for SENV DNA. There were no differences in the clinical, virologic and histologic features between patients with and without SENV infection. Eighteen of 102 patients with chronic hepatitis C who received IFN-alpha were positive for SENV DNA. The sustained response rate for hepatitis C virus (HCV) clearance after IFN-alpha treatment did not differ significantly between patients with SENV (28%) and without SENV infection (39%). SENV DNA levels decreased during therapy in 15 of 16 patients, and 11 of the 16 patients (69%) had a sustained loss of SENV DNA in response to IFN-alpha. In coinfected patients, SENV responses to IFN-alpha were significantly better in those who failed to clear HCV RNA than in those who lost HCV RNA (P =.013). In conclusion, SENV infection was frequently found in patients with chronic hepatitis C. SENV infection had no apparent influence on the severity of HCV-related liver disease or the HCV response to IFN-alpha. SENV was sensitive to IFN-alpha therapy and the majority of patients had a sustained virologic response.

Carbon nanotubes supported tyrosinase in the synthesis of lipophilic hydroxytyrosol and dihydrocaffeoyl catechols with antiviral activity against DNA and RNA viruses

Hydroxytyrosol and dihydrocaffeoyl catechols with lipophilic properties have been synthesized in high yield using tyrosinase immobilized on multi-walled carbon nanotubes by the Layer-by-Layer technique. All synthesized catechols were evaluated against a large panel of DNA and RNA viruses, including Poliovirus type 1, Echovirus type 9, Herpes simplex virus type 1 (HSV-1), Herpes simplex virus type 2 (HSV-2), Coxsackievirus type B3 (Cox B3), Adenovirus type 2 and type 5 and Cytomegalovirus (CMV). A significant antiviral activity was observed in the inhibition of HSV-1, HSV-2, Cox B3 and CMV. The mechanism of action of the most active dihydrocaffeoyl derivative was investigated against a model of HSV-1 infection.

TT virus infection in patients with chronic hepatitis C virus infection--effect of primers, prevalence, and clinical significance. Hepatitis Interventional Therapy Group

BACKGROUND/AIM

A novel DNA virus, TT virus (TTV), was recently identified in patients with post-transfusion non-A-G hepatitis. The aim of this study was to determine the prevalence and clinical significance of TTV infection in patients with chronic hepatitis C virus (HCV) infection.

METHODS

We analyzed pretreatment serum samples from 171 United States and European patients who relapsed after interferon-alpha treatment and were recruited into an interferon-alpha-2b/ribavirin combination treatment trial. TTV DNA was detected by PCR using two different set of primers (TTV-A and TTV-B) derived from open reading frames 1 and 2, respectively.

RESULTS

TTV was detected in 29.2% of the patients with the TTV-A primer set, 70.8% with the TTV-B primer-set, and 72.5% if positive by either/both sets of the primers. The amplicons generated by primer set A were sequenced and a phylogenetic tree was constructed. The 50 isolates belonged to group la (n=8), 1b (n=17), 2a (n=21), 2b (n=3), and 4 (n=1). There was no difference in demographic (age, sex distribution, estimated duration of HCV infection), biochemical (serum ALT levels), virologic (serum HCV RNA levels, HCV genotype distribution), or histologic scores, and their subsequent response to either interferon-alpha-2b or interferon-alpha-2b/ribavirin combination treatment.

CONCLUSIONS

The prevalence of TTV infection reported previously may have been significantly underestimated, based on the primers originally described and used by most studies. Although TTV infection is very common in patients with chronic HCV infection, it has no identifiable clinical significance.

Three cases with TT virus infection and idiopathic neonatal hepatitis

We present three cases of infants with idiopathic neonatal hepatitis showing diffuse intrahepatic fatty degeneration. Prolonged cholestasis has improved immediately upon intravenous administration of a high-dose gammaglobulin treatment in all three patients. The TT virus (TTV) genome was detectable in the serum of two patients, in the duodenal fluid of one and in the liver of all three. By analyzing sequence homology, we observed that the respective TTV isolated from serum, duodenal fluid and liver tissue were completely identical in cases 2 and 3. These findings suggest that TTV infection was one of the contributing factors for neonatal cholestasis in these patients. TTV was isolated from the serum of two out of the three mothers. The viruses were either completely or almost identical in sequence to those isolated from their respective infants, suggesting that they had been transmitted from mother to infant in these 2 cases. The patients presented here, whose livers were infected with the TTV and showed a favorable response to gammaglobulin therapy, may represent a subset of idiopathic neonatal hepatitis patients.

Antiviral activity of Illicium verum Hook. f. extracts against grouper iridovirus infection

Grouper iridovirus causes high mortality rates in cultured groupers, and effective treatment for grouper iridovirus infection is urgently required. Illicium verum Hook. f. is a well-known medicinal plant with a variety of biological activities. The aim of this study was to analyse the use of I. verum extracts to treat grouper iridovirus infection. The safe working concentration of each I. verum extract was identified both in vitro and in vivo as follows: I. verum aqueous extract (IVAE) ≤ 500 μg/ml; I. verum ethanol extract (IVEE) ≤ 250 μg/ml; shikimic acid (SKA) ≤ 250 μg/ml; trans-anethole (TAT) ≤ 800 μg/ml; 3,4-dihydroxybenzoic acid (DDBA) ≤ 400 μg/ml; and quercetin (QCE) ≤ 50 μg/ml. The inhibitory activity of each I. verum extract against grouper iridovirus infection was analysed using aptamer (Q2)-based fluorescent molecular probe (Q2-AFMP) and RT-qPCR. All of the I. verum extracts displayed dose-dependent antiviral activities against grouper iridovirus. Based on the achieved per cent inhibition, IVAE, IVEE, DDBA and QCE were associated with the greatest antiviral activity (all > 90%). Together, our results indicate that I. verum extracts have effective antiviral properties, making it an excellent potential source material for the development of effective treatment for grouper iridovirus infection.

Mechanism of enhanced Bombyx mori nucleopolyhedrovirus-resistance by titanium dioxide nanoparticles in silkworm

The infection of Bombyx mori nucleopolyhedrovirus (BmNPV) in silkworms is often lethal. It is difficult to prevent, and its lethality is correlated with both viral particle characteristics and silkworm strains. Low doses of titanium dioxide nanoparticles (TiO2 NPs) can promote silkworm growth and improve its resistance to organophosphate pesticides. In this study, TiO2 NPs' effect on BmNPV resistance was investigated by analyzing the characteristics of BmNPV proliferation and transcriptional differences in silkworm midgut and the transcriptional changes of immunity related genes after feeding with TiO2 NPs. We found that low doses of TiO2 NPs improved the resistance of silkworm against BmNPV by 14.88-fold, with the mortalities of the experimental group and control group being 0.56% and 8.33% at 144 h, respectively. The proliferation of BmNPV in the midgut was significantly increased 72 h after infection in both experimental and control groups; the control group reached the peak at 120 h, while the experimental group took 24 more hours to reach the maximal value that was 12.63 times lower than the control, indicating that TiO2 NPs can inhibit BmNPV proliferation in the midgut. Consistently, the expression of the BmNPV-resistant gene Bmlipase-1 had the same increase pattern as the proliferation changes. Immune signaling pathway analysis revealed that TiO2 NPs inhibited the proliferation of silkworm BmNPV to reduce the activation levels of janus kinase/signal transducer and activator of transcription (JAK/STAT) and phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway, while promoting the expression of Bmakt to improve the immunity. Overall, our results demonstrate that TiO2 NPs increase silkworm resistance against BmNPV by inhibiting virus proliferation and improving immunity in silkworms.

Relationship between Expression of Cellular Receptor-27.8 kDa and Lymphocystis Disease Virus (LCDV) Infection

The 27.8 kDa membrane protein from flounder (Paralichthys olivaceus) gill (FG) cells was previously identified as a putative cellular receptor involved in lymphocystis disease virus (LCDV) infection. In this paper, the expression of receptor-27.8 kDa (27.8R) and LCDV loads in FG cells and hirame natural embryo (HINAE) cells were investigated upon LCDV infection and anti-27.8R monoclonal antibody (MAb) treatment. The results showed the 27.8R was expressed and co-localized with LCDV in both FG and HINAE cell surface. After LCDV infection, the expression of 27.8R exhibited a dose-dependent up-regulation with the increasing of LCDV titers, and demonstrated a tendency to increase firstly and then decrease during a time course up to 9 days; LCDV copies showed a similar variation trend to the 27.8R expression, however, it reached the highest level later than did the 27.8R expression. Additionally, the 27.8R expression and LCDV copies in FG cells were higher than those in HINAE cells. In the presence of increasing concentration of the anti-27.8R MAbs, the up-regulation of 27.8R expression and the copy numbers of LCDV significantly declined post LCDV infection, and the cytopathic effect induced by LCDV in the two cell lines was accordingly reduced, indicating anti-27.8R MAbs pre-incubation could inhibit the up-regulation of 27.8R expression and LCDV infection. These results suggested that LCDV infection could induce up-regulation of 27.8R expression, which in turn increased susceptibility and availability of FG and HINAE cells for LCDV entry, providing important new insights into the LCDV replication cycle and the interaction between this virus and the host cells.

Clinical implications of TT virus superinfection in patients with chronic hepatitis C

OBJECTIVE

TT virus (TTV) has been identified as a candidate agent of non-A-E hepatitis virus. We investigated superinfection of TTV in patients with chronic hepatitis C and studied the susceptibility to interferon (IFN) treatment and its association with liver disease caused by hepatitis C virus (HCV).

METHODS

TTV DNA was examined using the seminested polymerase chain reaction (PCR), and its virus level was measured by the real-time fluorometric PCR.

RESULTS

TTV DNA was detected in 20 of 102 (19.6%) patients examined. There was no significant difference in the alanine aminotransferase (ALT) level between patients with or without TTV DNA. Quantitative analysis of HCV RNA and TTV DNA revealed no correlation between virus levels in HCV/TTV-coinfected patients. Both TTV and HCV were sensitive to IFN therapy. Complete response to IFN with a sustained loss of viremia for 24 wk after completion of IFN treatment was found in 11 of 20 (55%) patients with respect to TTV DNA and in five of 20 (25%) patients with respect to HCV RNA. The mean pretreatment HCV RNA level was significantly lower in the complete-response cases than in the no-response cases, but there was no significant difference in the pretreatment TTV DNA levels between them. ALT normalization resulting from IFN therapy was not attributable to the eradication of TTV DNA but was attributable to that of HCV RNA. Superinfection by TTV did not influence the effect of IFN against HCV. No specific TTV genotype correlating with IFN sensitivity was found.

CONCLUSIONS

These results suggest that TTV infection stands independent of HCV infection, with no influence on liver injury as a result of HCV infection.

Clinical management of selected oral fungal and viral infections during HIV-disease

The purpose of this review is to describe current possibilities of management of selected fungal and viral oral opportunistic infections including oral candidiasis, herpes simplex type 1 and 2-related lesions (HSV1,2), oral hairy leukoplakia (OHL) and oral lesions associated with human papilloma viruses (HPV). Less common diseases such as cytomegalovirus infection or human herpes virus type 8 associated with Kaposi's sarcoma and others are not considered. In a number of instances lifelong therapy or prophylaxis has to be instituted. Antiretroviral combination therapy, also called highly active antiretroviral therapy (HAART), has considerably changed the frequency of oral lesions caused by opportunistic agents. A short description of the antiretroviral agents available including respective side-effects is presented.

Immune enhancement of chemotherapeutants on lymphocystis disease virus (LDV) infected Paralichthys olivaceus

In olive flounder, Paralichthys olivaceus infected with lymphocystis disease virus (LDV) bath treatment with formalin, hydrogen peroxide or Jenoclean at 50, 100, and 200 ppm daily 10 min for 60 days enhanced the innate immune response and disease resistance. Jenoclean enhanced the immune parameters at the lowest concentration of 50 ppm; on the other hand, hydrogen peroxide bath treatment enhanced the immunity level at 100 ppm, while formalin was effective only at 200 ppm. A low cumulative mortality and high relative percent survival was noted in Jenoclean treated group followed by formalin and hydrogen peroxide treated groups. In olive flounder at low concentrations of 50 ppm or 100 ppm hydrogen peroxide and Jenoclean effectively prevent LDV infection.

TT virus infection in patients with chronic hepatitis B and response of TTV to lamivudine

AIM: To investigate the responses of TT virus (TTV) and hepatitis B virus (HBV) to a long-term lamivudine therapy.

METHODS: Sixteen patients infected with both TTV and HBV were treated with lamivudine 100 mg daily for 30 mo. Blood samples were drawn at the beginning of the therapy and subsequently at month 3, 6, 9, 12 and 30. Serum TTV was quantified by real time PCR and serum HBV was detected by hybridization assay and nested polymerase chain reaction.

RESULTS: TTV infection was detected in 100% of HBV-infected patients. Loss of serum TTV DNA after one year of treatment occurred in 1/16 (6%) patients. At the end of therapy, TTV DNA was positive in 94% of them. The decline of HBV viremia was evident at 3 mo after therapy and the response rate was 31%, 44%, 63%, 50% and 50% at month 3, 6, 9, 12 and 30, respectively.

CONCLUSION: TTV replication is not sensitive to lamivudine and is highly prevalent in HBV-infected patients.