Pronounced anti-HIV-1 activity of foscarnet in patients without cytomegalovirus infection

Foscarnet Salvage Therapy for Patients with Late-Stage HIV Disease and Multiple Drug Resistance

Objective

To evaluate the efficacy of foscarnet on HIV infection in patients with late-stage HIV disease and multiple drug resistance.

Methods

Three drugs experienced patients with plasma viral load (pVL) >50,000 copies/ml and CD4+ T-cell counts <100/mm3 were eligible for this open-label, single-arm, add-on pilot study. Foscarnet induction therapy consisted of 5 g intravenously twice daily for 6 weeks, in addition to a stable antiretroviral regimen. Patients with at least 1 log10 decrease in pVL at week 6 (W6), were given foscarnet 5 g intravenously twice daily on two consecutive days each week. Primary endpoint was the virological response rate at W6.

Results

Eleven patients were enrolled with a median baseline pVL at 5.16 log10 copies/ml, median CD4+ T-cell count at 10/mm3 and median number of mutations of 9, 2 and 12 associated with resistance to nucleoside reverse transcriptase inhibitors (NRTIs), non-NRTIs and protease inhibitors, respectively. One patient discontinued foscarnet at W2 because of renal toxicity. In an intent-to-treat analysis, the median change in pVL from baseline was -1.99 log10 copies/ml at W2 and -1.79 log10 copies/ml at W6. Eight out of eleven patients had a fall in pVL of at least 1 log10 at W6, and six started maintenance therapy. The median fall in pVL after 12 weeks of maintenance therapy was -0.85 log10 copies/ml in the four patients who reached W12, and the median increase of CD4+ T-cell count was 60/mm3.

Conclusion

In patients with HIV mutations conferring resistance to all antiretroviral drug classes, foscarnet markedly reduced plasma HIV load and improved immunological status.

The Rad27 (Fen-1) nuclease inhibits Ty1 mobility in Saccharomyces cerevisiae

Although most Ty1 elements in Saccharomyces cerevisiae are competent for retrotransposition, host defense genes can inhibit different steps of the Ty1 life cycle. Here, we demonstrate that Rad27, a structure-specific nuclease that plays an important role in DNA replication and genome stability, inhibits Ty1 at a post-translational level. We have examined the effects of various rad27 mutations on Ty1 element retrotransposition and cDNA recombination, termed Ty1 mobility. The point mutations rad27-G67S, rad27-G240D, and rad27-E158D that cause defects in certain enzymatic activities in vitro result in variable increases in Ty1 mobility, ranging from 4- to 22-fold. The C-terminal frameshift mutation rad27-324 confers the maximum increase in Ty1 mobility (198-fold), unincorporated cDNA, and insertion at preferred target sites. The null mutation differs from the other rad27 alleles by increasing the frequency of multimeric Ty1 insertions and cDNA recombination with a genomic element. The rad27 mutants do not markedly alter the levels of Ty1 RNA or the TyA1-gag protein. However, there is an increase in the stability of unincorporated Ty1 cDNA in rad27-324 and the null mutant. Our results suggest that Rad27 inhibits Ty1 mobility by destabilizing unincorporated Ty1 cDNA and preventing the formation of Ty1 multimers.

Incidence and trends in Kaposi's sarcoma in the era of effective antiretroviral therapy

OBJECTIVE

To evaluate the impact of antiretroviral and antiherpesvirus therapies on the incidence of KS and assess trends in incidence of Kaposi's sarcoma (KS) in a large multicenter HIV/AIDS surveillance system between 1990 and 1998.

METHODS

Incidence was calculated per 100 person-years (py); the effects of therapies on risk for KS were calculated by using multivariate Poisson regression controlling for gender, race/ethnicity, age, HIV exposure mode, CD4+ cell count, and calendar year. Antiretroviral therapy was defined as monotherapy, dual therapy, or triple therapy (95% of triple therapy regimens contained a protease inhibitor). Acyclovir, ganciclovir, and foscarnet were the antiherpesvirus therapies evaluated.

RESULTS

There were 37,303 HIV-infected people in the study contributing 70,238 py. Those prescribed triple antiretroviral therapy had a 50% reduction in the incidence of KS (95% confidence interval, 20%-70%) compared with those who were not prescribed antiretroviral therapy and there was a reduction in risk for KS among persons prescribed foscarnet (p =.05). Overall, KS incidence declined an estimated 8.8% per year (observed incidence 4. 1 per 100 py in 1990 to 0.7 per 100 py in 1998; p <.001).

CONCLUSION

Incidence of KS is declining in this large U.S. population and may continue to decline as new, more effective antiretroviral agents are developed and used widely.

Nucleotide excision repair/TFIIH helicases RAD3 and SSL2 inhibit short-sequence recombination and Ty1 retrotransposition by similar mechanisms

Eukaryotic genomes contain potentially unstable sequences whose rearrangement threatens genome structure and function. Here we show that certain mutant alleles of the nucleotide excision repair (NER)/TFIIH helicase genes RAD3 and SSL2 (RAD25) confer synthetic lethality and destabilize the Saccharomyces cerevisiae genome by increasing both short-sequence recombination and Ty1 retrotransposition. The rad3-G595R and ssl2-rtt mutations do not markedly alter Ty1 RNA or protein levels or target site specificity. However, these mutations cause an increase in the physical stability of broken DNA molecules and unincorporated Ty1 cDNA, which leads to higher levels of short-sequence recombination and Ty1 retrotransposition. Our results link components of the core NER/TFIIH complex with genome stability, homologous recombination, and host defense against Ty1 retrotransposition via a mechanism that involves DNA degradation.