Novel, selective CDK9 inhibitors for the treatment of HIV infection

Cyclin Dependent Kinases (CDKs) are important regulators of cell cycle and gene expression. Since an up-to-date review about the pharmacological inhibitors of CDK family (CDK1-10) is not available; therefore in the present paper we briefly summarize the most relevant inhibitors and point out the low number of selective inhibitors. Among CDKs, CDK9 is a validated pathological target in HIV infection, inflammation and cardiac hypertrophy; however selective CDK9 inhibitors are still not available. We present a selective inhibitor family of CDK9 based on the 4-phenylamino-6- phenylpyrimidine nucleus. We show a convenient synthetic method to prepare a useful intermediate and its derivatisation resulting in novel compounds. The CDK9 inhibitory activity of the derivatives was measured in specific kinase assay and the CDK inhibitory profile of the best ones (IC(50) < 100 nM) was determined. The most selective compounds had high selectivity over CDK1, 2, 3, 5, 6, 7 and showed at least one order of magnitude higher inhibitory activity over CDK4 inhibition. The most selective molecules were examined in cytotoxicity assays and their ability to inhibit HIV-1 replication was determined in cellular assays.

Microbe-induced epigenetic alterations in host cells: the coming era of patho-epigenetics of microbial infections. A review

It is well documented that the double-stranded DNA (dsDNA) genomes of certain viruses and the proviral genomes of retroviruses are regularly targeted by epigenetic regulatory mechanisms (DNA methylation, histone modifications, binding of regulatory proteins) in infected cells. In parallel, proteins encoded by viral genomes may affect the activity of a set of cellular promoters by interacting with the very same epigenetic regulatory machinery. This may result in epigenetic dysregulation and subsequent cellular dysfunctions that may manifest in or contribute to the development of pathological changes (e.g. initiation and progression of malignant neoplasms; immunodeficiency). Bacteria infecting mammals may cause diseases in a similar manner, by causing hypermethylation of key cellular promoters at CpG dinucleotides (promoter silencing, e.g. by Campylobacter rectus in the placenta or by Helicobacter pylori in gastric mucosa). I suggest that in addition to viruses and bacteria, other microparasites (protozoa) as well as macroparasites (helminths, arthropods, fungi) may induce pathological changes by epigenetic reprogramming of host cells they are interacting with. Elucidation of the epigenetic consequences of microbe-host interactions (the emerging new field of patho-epigenetics) may have important therapeutic implications because epigenetic processes can be reverted and elimination of microbes inducing patho-epigenetic changes may prevent disease development.

Increased incidence of genetic human prion disease in Hungary

The authors performed analysis of the prion protein gene (PRNP) in 27 out of 109 confirmed prion disease patients between 1994 and 2004. E200K mutation was found in 17 cases. Another 10 patients, lacking PRNP analysis, showed positive family history. The mean annual incidence (0.27/million) and proportion (25.6%) of genetic prion disease is unusually high in Hungary and might be related to the migration of ancestors from the Slovakian focus.

A 30 kb region of the Epstein-Barr virus genome is colinear with the rearranged human immunoglobulin gene loci: implications for a "ping-pong evolution" model for persisting viruses and their hosts. A review

The left part of the Epstein-Barr virus (EBV) genome exhibits a strong colinearity of structural and functional elements with the immunoglobulin (Ig) gene loci which is only partially reflected in nucleotide sequence homologies. We propose that this colinearity may be the result of an inter-dependent co-evolution of the immunoglobulin loci together with EBV. Our observation could help elucidating the mechanisms of somatic hypermutation, explaining the ability of EBV to accidentally cause tumors, and shedding more light on the general mechanisms of viral and organismal evolution. We suggest that persisting viruses served as a complement for the organismal germline like in a ping-pong game and outline The Ping-Pong Evolution Hypothesis.

Genetic subtypes of HIV type 1 in Hungary

We examined the diversity of HIV-1 subtypes in 11 adults from Hungary, using the heteroduplex mobility assay (HMA) and DNA sequencing. HMA results showed that HIV-1 gp120 sequences from 10 patients were of subtype B, whereas 1 patient, infected in Africa, carried a subtype C strain. DNA sequencing confirmed the HMA results and revealed a high intrasubtype diversity in the C2V3 region of env in different clade B isolates, which suggests multiple introduction of subtype B to Hungary. This study shows that subtype B is the predominant HIV-1 clade in Hungary.

Strong correlation between the complement-mediated antibody-dependent enhancement of HIV-1 infection and plasma viral load

OBJECTIVE

We have previously demonstrated that complement-mediated antibody-dependent enhancement (C-ADE) of HIV-1 infection correlates with accelerated immunosuppression and disease progression in HIV-1-infected individuals. In the present work the relationship between C-ADE and plasma HIV-1 RNA concentrations was studied to determine the effect of C-ADE on viral replication.

METHODS

Three studies were performed: (a) C-ADE and HIV-1 RNA concentrations were determined in the serum and plasma aliquots taken at the same time from 98 HIV patients, mostly in the advanced stage of the disease; (b) the above two parameters as well as HIV enzyme-linked immunosorbent assay (ELISA)-reactive antibodies (Abbott HIV 1/2 test), and p24 antigen levels (Abbott antigen test; Abbott, Delkenheim, Germany) were determined in four seroconversion panels purchased from the Boston Biomedica firm; (c) changes of HIV-1 RNA concentration and C-ADE during a 17 month follow-up period were determined in 18 HIV-infected patients. C-ADE was measured by the method previously established in our laboratories. The results were expressed by an enhancement/neutralization index (E/NI). HIV-1 RNA levels were determined with the Amplicor monitor kit (Roche, Basel, Switzerland), and in some experiments with the nucleic acid sequence based amplification (Organon Teknika, Turnhout, Belgium) kits.

RESULTS

(a) We found a highly significant (P<0.0001) positive correlation between E/NI values reflecting the extent of HIV-1 infection enhancement and plasma HIV-1 RNA levels. Both E/NI and HIV-1 RNA levels negatively correlated to the CD4 cell counts. (b) C-ADE was first detected just before, or concomitantly with, seroconversion in 4/4 seroconversion panels. (c) Both E/NI values and HIV-1 RNA levels significantly (P<0.001) increased during a 17 month observation period in 18 HIV-infected patients.

CONCLUSION

We found strong association between the extent of the complement-mediated antibody-dependent enhancement of HIV-1 infection and the plasma viral load in HIV patients. On the basis of these findings, C-ADE correlates with HIV replication in vivo, and potentially contributes to the progression of HIV disease.

S-methylthio-cysteine and cystamine are potent stimulators of thiol production and glutathione synthesis

The effects of methylthio-cysteine disulfide (MT-Cy) and cystamine (CAM) on the thiol production and glutathione content of a human T cell line (CEM-SS) have been investigated. MT-Cy per se and CAM in the presence of cystine greatly enhanced thiol production and glutathione content of cells while cystine alone exerted no or slight influence in the first hours. The MT-Cy- or CAM-induced extracellular SH-generation was observed both in a complete nutrient medium and even more in SH-free D-PBS. The acid-soluble thiol level and glutathione content of cells elevated markedly (up to 5-6 fold in two hours) when incubating cells in complete medium. Inhibition of glutathione synthesis by DL-buthionine (S,R)-sulfoximine did not alter the MT-Cy- or CAM-induced extracellular thiol production indicating that glutathione synthesis is not involved in this effect. The results suggest that MT-Cy easily enters the cells thus accelerating the thiol cycle in SH-poor medium while CAM promotes cystine uptake into the cells. Phenylalanine and leucine inhibited both MT-Cy- and CAM-dependent thiol production in D-PBS most effectively suggesting the involvement of the L membrane transport system in these effects.

Plasma HIV-1 load and disease progression in HIV-infected patients in Hungary

Nucleic Acid Sequence Based Amplification (NASBA) is a suitable method for the quantification of HIV-1 RNA in plasma and serum samples. Since determination of the viral load appears to be a valuable marker for the prediction of disease progression and for monitoring the efficiency of antiretroviral therapy, the National AIDS Committee initiated the introduction of NASBA in Hungary at the end of 1996. We obtained plasma samples from patients with ARC and AIDS of the Szt. László Hospital, Budapest. We found an increased viral burden in untreated AIDS (CDC group C) patients compared to untreated ARC (CDC group B) patients. In plasma samples of clinically stable ARC and AIDS patients treated with antiretroviral drugs we detected relatively low HIV-1 RNA copy levels while similarly treated ARC and AIDS patients with progressive disease had high HIV-1 RNA copy numbers. The CD4+ T-cell count was lower in AIDS patients compared to ARC patients, as expected. In general, there was an inverse correlation (r = -0.487, P < 0.0001) between CD4+ T-cell counts and HIV-1 RNA levels. We concluded that measurement of HIV-1 RNA plasma level has an important role in assessing prognosis and effects of antiretroviral therapy in HIV-infected patients.

Prospects for the control of AIDS patients by introducing defective-HIV harbouring leukocytes

Introduction of leukocytes harbouring an artificially constructed defective HIV provirus into AIDS patients may result in inducing superinfection resistance against HIV and interfering with HIV receptors or replication of HIV. All these may slow down progression of the disease.

Homologies between small nuclear RNAs and LAV/HTLV-III sequences and their possible role in the cytopathic effect of the virus

The mechanism of action of LAV/HTLV-III resulting in a pronounced cytopathic effect is still unknown. We demonstrate that the long terminal repeat (LTR) sequence and env gene of LAV/HTLV-III contain regions of 70-80% homology and/or complementarity with regions of small nuclear (sn) RNAs U1 and U2. On this basis, we hypothesize that the cytotoxic effect of LAV/HTLV-III is due - at least partly - to the inhibition of processing of cellular hnRNAs by competing for splice junction sites and/or by complexing with U1 and especially U2 RNAs.

Homologies between a brain-specific identifier (ID) sequence and regions of Harvey murine sarcoma virus and Rous sarcoma virus genomes. Putative role of identifier sequences in the tissue specificity of malignant transformation by RNA tumor viruses

As a step toward understanding of the tissue specificity of cellular transformation by RNA tumor viruses were looked for the presence of a putative brain specific regulatory (identifier) sequence (C82B) in the genome of various oncornaviruses. The genomes of Harvey murine sarcoma virus and Rous sarcoma virus contain sequences flanking the viral oncogenes with greater than 80% and greater than 60% homology to C82B, respectively. We suggest that identifier sequences acquired by oncoviruses may determine the potential target cells of malignant transformation after virus penetration.