A sensitive assay for detection and measurement of neutralising antibody to human immunodeficiency virus

Knockdown of ERM family member moesin in host cells increases HIV type 1 replication

Moesin is a member of the ERM (ezrin, radixin, moesin) family of cytoskeleton/membrane structure organizing and signal transduction proteins. Previously, we found an increased expression of moesin during HIV-1 infection. Moesin was also reported to be incorporated into HIV-1 virions. To analyze whether moesin is a host factor affecting the replication cycle of human immunodeficiency virus type 1 (HIV-1), we used small interfering RNAs (siRNAs) to evaluate the effect of moesin knockdown on HIV-1 replication in P4-CCR5 cells. Moesin's knockdown did not affect the cell viability or cell phenotype. Interestingly, we observed a marked increase in viral replication, as demonstrated by enhanced HIV-1 RNA, p24 antigen, and ß-galactosidase reporter expression. Moesin-dependent enhancement of HIV-1 replication was confirmed in lymphocytic host cells (Jurkat). These results suggest an overall rather restrictive role of moesin for HIV-1 replication in host cells in vitro.

HIV-1 infection suppresses expression of host cell cycle-associated gene PDS5A

OBJECTIVE

To unravel the interplay between HIV-1 and its host cell, the effect of HIV-1 infection on cellular gene expression was investigated.

METHODS

HIV-1(SF33)-infected and uninfected H9 T cells were screened by differential display and RNase protection assay. The finding (PDS5A) was confirmed in HIV-1(Lai)-infected P4-CCR5 HeLa cells, which were also examined after PDS5A siRNA knockdown in regard to HIV-1 replication by quantitative RT-PCR, p24 ELISA and LTR-driven β-galactosidase expression. The PDS5A knockdown effect on cellular gene expressions was studied by microarray analysis. PDS5A tissue expression was determined by Northern blotting.

RESULTS

Regulator of cohesion maintenance, homolog A (PDS5A) was found to be down-regulated by HIV-1. When PDS5A was suppressed by siRNA, HIV-1 replication was unaffected. PDS5A was found to be highly expressed in skeletal muscle tissue, and to lesser degrees in pancreas, heart, placenta, lung, kidney, liver and brain. Microarray analysis of PDS5A knockdown revealed 91 differential gene products over-representing cell cycle, transport and protein stability regulation, including 4 genes (PP2A, RANTES, PCAF, TCF7L2) previously reported to interact with HIV-1.

CONCLUSION

The data show a downregulation of proliferation-associated host gene PDS5A and suggest a role of PDS5A in HIV-1-induced cellular pathogenesis but not viral replication.

Inhibition of HIV-1 replication by small interfering RNAs directed against glioma pathogenesis related protein (GliPR) expression

BACKGROUND

Previously, we showed that glioma pathogenesis related protein (GliPR) is induced in CEM T cells upon HIV-1 infection in vitro. To examine whether GliPR plays a role as HIV dependency factor (HDF), we tested the effect of GliPR suppression by siRNA on HIV-1 replication.

RESULTS

Induction of GliPR expression by HIV-1 was confirmed in P4-CCR5 cells. When GliPR was suppressed by siRNA, HIV-1 replication was significantly reduced as measured by HIV-1 transcript levels, HIV-1 p24 protein levels, and HIV-1 LTR-driven reporter gene expression, suggesting that GliPR is a cellular co-factor of HIV-1. Microarray analysis of uninfected HeLa cells following knockdown of GliPR revealed, among a multitude of gene expression alterations, a down-regulation of syndecan-1, syndecan-2, protein kinase C alpha (PRKCA), the catalytic subunit beta of cAMP-dependent protein kinase (PRKACB), nuclear receptor co-activator 3 (NCOA3), and cell surface protein CD59 (protectin), all genes having relevance for HIV-1 pathology.

CONCLUSIONS

The up-regulation of GliPR by HIV-1 and the early significant inhibition of HIV-1 replication mediated by knockdown of GliPR reveal GliPR as an important HIV-1 dependency factor (HDF), which may be exploited for HIV-1 inhibition.

SIV- and HIV-2-neutralising antibodies in infected macaques measured by a novel and simple neutralisation test based on a non-commercial antigen-ELISA

A method for the measurement of neutralising antibodies (nab) directed against SIVmac or HIV-2 was developed. The assay is based on antigen detection using a non-commercial enzyme-linked immunosorbent assay (ELISA). Studies were carried out to determine the influence of the test conditions on the nab titre. The sensitivity of the assay depended mainly on the virus dose and the length of incubation of the serum-virus-mixture. Prolongation of the culture time from 9 to 11 days increased the validity of the results. Applying this neutralisation assay on sequential serum samples from SIV mac- or HIV-2ben-infected macaques, a considerable variation was found in nab titres between individual animals. Whereas after infection with SIVmac, in vitro-neutralisation seems to correlate with protection against disease, and the lower pathogenity of HIV-2ben in macaques compared with SIVmac is not due to the differences in nab titres.

Assessment of chemical disinfectants against human immunodeficiency virus: overcoming the problem of cytotoxicity and the evaluation of selected actives

The aim of this study was to develop a standardised technique for assessing the virucidal activity of commercial disinfectants against human immunodeficiency virus (HIV). In the absence of any model procedure for HIV a protocol based on German DVV guidelines was developed. A major difficulty associated with such studies is the cytotoxic effect of the biocide on the target cells used in infectivity assays. This problem is most commonly overcome by dilution of the virus-disinfectant mixture, however, this requires high titre (> or = 10(7) TCID50) virus which is difficult to achieve with HIV. We employed a simple washing technique which effectively removed cytotoxicity while retaining infectivity. Incorporated into a standard suspension test, this method supported by virus isolation procedures was sensitive and reproducible. The reliability of the procedure was confirmed by evaluating the efficacy of some commercially available cidals which were known to be cytotoxic; namely two instrument disinfectants, Sactimed-I-Steril, an aldehyde based product, Sactimed-I-Sinald a guanide/quaternary-ammonium combination, and Levermed, an alcohol based hand disinfectant.