HIV-1 reservoirs preclude virus eradication in patients receiving highly active antiretroviral therapy (HAART). The best characterized reservoir is a small, difficult-to-quantify pool of resting ...memory CD4(+) T cells carrying latent but replication-competent viral genomes. Because strategies targeting this latent reservoir are now being tested in clinical trials, well-validated high-throughput assays that quantify this reservoir are urgently needed. Here we compare eleven different approaches for quantitating persistent HIV-1 in 30 patients on HAART, using the original viral outgrowth assay for resting CD4(+) T cells carrying inducible, replication-competent viral genomes as a standard for comparison. PCR-based assays for cells containing HIV-1 DNA gave infected cell frequencies at least 2 logs higher than the viral outgrowth assay, even in subjects who started HAART during acute/early infection. This difference may reflect defective viral genomes. The ratio of infected cell frequencies determined by viral outgrowth and PCR-based assays varied dramatically between patients. Although strong correlations with the viral outgrowth assay could not be formally excluded for most assays, correlations achieved statistical significance only for integrated HIV-1 DNA in peripheral blood mononuclear cells and HIV-1 RNA/DNA ratio in rectal CD4(+) T cells. Residual viremia was below the limit of detection in many subjects and did not correlate with the viral outgrowth assays. The dramatic differences in infected cell frequencies and the lack of a precise correlation between culture and PCR-based assays raise the possibility that the successful clearance of latently infected cells may be masked by a larger and variable pool of cells with defective proviruses. These defective proviruses are detected by PCR but may not be affected by reactivation strategies and may not require eradication to accomplish an effective cure. A molecular understanding of the discrepancy between infected cell frequencies measured by viral outgrowth versus PCR assays is an urgent priority in HIV-1 cure research.
HIV-1 persists in infected individuals in a stable pool of resting CD4(+) T cells as a latent but replication-competent provirus. This latent reservoir is the major barrier to the eradication of ...HIV-1. Clinical trials are currently underway investigating the effects of latency-disrupting compounds on the persistence of the latent reservoir in infected individuals. To accurately assess the effects of such compounds, accurate assays to measure the frequency of latently infected cells are essential. The development of a simpler assay for the latent reservoir has been identified as a major AIDS research priority. We report here the development and validation of a rapid viral outgrowth assay that quantifies the frequency of cells that can release replication-competent virus following cellular activation. This new assay utilizes bead and column-based purification of resting CD4(+) T cells from the peripheral blood of HIV-1 infected patients rather than cell sorting to obtain comparable resting CD4(+) T cell purity. This new assay also utilizes the MOLT-4/CCR5 cell line for viral expansion, producing statistically comparable measurements of the frequency of latent HIV-1 infection. Finally, this new assay employs a novel quantitative RT-PCR specific for polyadenylated HIV-1 RNA for virus detection, which we demonstrate is a more sensitive and cost-effective method to detect HIV-1 replication than expensive commercial ELISA detection methods. The reductions in both labor and cost make this assay suitable for quantifying the frequency of latently infected cells in clinical trials of HIV-1 eradication strategies.
HIV-1 protease inhibitors (PIs) are among the most effective antiretroviral drugs. They are characterized by highly cooperative dose-response curves that are not explained by current pharmacodynamic ...theory. An unresolved problem affecting the clinical use of PIs is that patients who fail PI-containing regimens often have virus that lacks protease mutations, in apparent violation of fundamental evolutionary theory. Here, we show that these unresolved issues can be explained through analysis of the effects of PIs on distinct steps in the viral life cycle. We found that PIs do not affect virion release from infected cells but block entry, reverse transcription, and post-reverse transcription steps. The overall dose-response curves could be reconstructed by combining the curves for each step using the Bliss independence principle, showing that independent inhibition of multiple distinct steps in the life cycle generates the highly cooperative dose-response curves that make these drugs uniquely effective. Approximately half of the inhibitory potential of PIs is manifest at the entry step, likely reflecting interactions between the uncleaved Gag and the cytoplasmic tail (CT) of the Env protein. Sequence changes in the CT alone, which are ignored in current clinical tests for PI resistance, conferred PI resistance, providing an explanation for PI failure without resistance.
Elite Controllers or Suppressors (ES) are patients who control HIV replication without antiretroviral therapy. In this study, we compared baseline and inducible HIV-1 mRNA levels in CD4+ T cells from ...ES and chronic progressors (CPs) receiving suppressive antiretroviral therapy.
We quantified basal levels of cell associated HIV-1 mRNA in CD4+ T cells isolated from CPs and ES. Additionally, we measured the fold upregulation of intracellular HIV-mRNA after stimulation of CD4+ T cells with phorbol 12-myristate 13-acetate (PMA) and ionomycin, and quantified the amount of HIV-mRNA levels released into culture supernatant.
ES have significantly less cell associated HIV-mRNA per 5x10
cells (p = 0.003); 8 of 10 CPs had quantifiable HIV-1 mRNA at baseline, whereas this was present in only 2 of 10 ES. Upon stimulation with PMA and ionomycin, 4 of 5 CPs and 7 of 9 ES showed increased cell associated HIV-mRNA. Interestingly, released HIV-1 mRNA could be detected in supernatants of CD4+ T cells stimulated with PMA/ionomycin from 5 of 8 ES.
Our results demonstrate that while the baseline levels of cell associated HIV-1 mRNA are significantly lower in ES compared to CPs, stimulation of CD4+ T cells results in a comparable relative upregulation of viral transcription.
HIV-1 persists in infected individuals in a stable pool of resting CD4+ T cells as a latent but replication-competent provirus. This latent reservoir is the major barrier to the eradication of HIV-1. ...Clinical trials are currently underway investigating the effects of latency-disrupting compounds on the persistence of the latent reservoir in infected individuals. To accurately assess the effects of such compounds, accurate assays to measure the frequency of latently infected cells are essential. The development of a simpler assay for the latent reservoir has been identified as a major AIDS research priority. We report here the development and validation of a rapid viral outgrowth assay that quantifies the frequency of cells that can release replication-competent virus following cellular activation. This new assay utilizes bead and column-based purification of resting CD4+ T cells from the peripheral blood of HIV-1 infected patients rather than cell sorting to obtain comparable resting CD4+ T cell purity. This new assay also utilizes the MOLT-4/CCR5 cell line for viral expansion, producing statistically comparable measurements of the frequency of latent HIV-1 infection. Finally, this new assay employs a novel quantitative RT-PCR specific for polyadenylated HIV-1 RNA for virus detection, which we demonstrate is a more sensitive and cost-effective method to detect HIV-1 replication than expensive commercial ELISA detection methods. The reductions in both labor and cost make this assay suitable for quantifying the frequency of latently infected cells in clinical trials of HIV-1 eradication strategies.
HIV-1 reservoirs preclude virus eradication in patients receiving highly active antiretroviral therapy (HAART). The best characterized reservoir is a small, difficult-to-quantify pool of resting ...memory CD4+ T cells carrying latent but replication-competent viral genomes. Because strategies targeting this latent reservoir are now being tested in clinical trials, well-validated high-throughput assays that quantify this reservoir are urgently needed. Here we compare eleven different approaches for quantitating persistent HIV-1 in 30 patients on HAART, using the original viral outgrowth assay for resting CD4+ T cells carrying inducible, replication-competent viral genomes as a standard for comparison. PCR-based assays for cells containing HIV-1 DNA gave infected cell frequencies at least 2 logs higher than the viral outgrowth assay, even in subjects who started HAART during acute/early infection. This difference may reflect defective viral genomes. The ratio of infected cell frequencies determined by viral outgrowth and PCR-based assays varied dramatically between patients. Although strong correlations with the viral outgrowth assay could not be formally excluded for most assays, correlations achieved statistical significance only for integrated HIV-1 DNA in peripheral blood mononuclear cells and HIV-1 RNA/DNA ratio in rectal CD4+ T cells. Residual viremia was below the limit of detection in many subjects and did not correlate with the viral outgrowth assays. The dramatic differences in infected cell frequencies and the lack of a precise correlation between culture and PCR-based assays raise the possibility that the successful clearance of latently infected cells may be masked by a larger and variable pool of cells with defective proviruses. These defective proviruses are detected by PCR but may not be affected by reactivation strategies and may not require eradication to accomplish an effective cure. A molecular understanding of the discrepancy between infected cell frequencies measured by viral outgrowth versus PCR assays is an urgent priority in HIV-1 cure research.
The coronavirus disease (COVID-19) infection rate and mortality among Nigerian health care workers appear to be on the increase. This study determined the level of knowledge, attitude, practices, and ...impact of COVID-19 infection on healthcare workers (HCWs) working in a South-Eastern Nigerian state.
This was a web-based, cross-sectional study conducted among healthcare workers in South-eastern, Nigeria during the lockdown period. Socio-demographic profile, knowledge of COVID-19, fears and impact concerning COVID-19, attitude of health workers to work, preventive practices during this pandemic period were obtained. Data were analysed using STATA 16.0. Chi-square and Fisher's exact tests of association were used to determine the association between variables, with the significance level set at p < 0.05.
A total of 403 health care workers participated in the study. Majority of participants (n = 357, 88.59%) had good knowledge and good preventive practices (n = 328, 81.39%) of COVID-19. A significant proportion of respondents had a poor attitude to work (n = 101, 25.06%) and an attitude of indifference (n = 233, 57.82%). Almost half (48.64%) of participants had been negatively affected by COVID-19. Knowledge significantly influenced practice (p = 0.029). Lack of Personal protective equipment, fear of dying and going to common places, had a significant impact on the attitude of workers.
Good knowledge which influenced practice, high use of preventive practices, with associated poor and indifferent attitude was noted among healthcare workers. Fear of death and lack of personal protective equipment had a strong impact on attitude. Female HCWs had poorer attitude to work than males.
The potential for an intelligent transportation system (ITS) has been made possible by the growth of the Internet of things (IoT) and artificial intelligence (AI), resulting in the integration of IoT ...and ITS—known as the Internet of vehicles (IoV). To achieve the goal of automatic driving and efficient mobility, IoV is now combined with modern communication technologies (such as 5G) to achieve intelligent connected vehicles (ICVs). However, IoV is challenged with security risks in the following five (5) domains: ICV security, intelligent device security, service platform security, V2X communication security, and data security. Numerous AI models have been developed to mitigate the impact of intrusion threats on ICVs. On the other hand, the rise in explainable AI (XAI) results from the requirement to inject confidence, transparency, and repeatability into the development of AI for the security of ICV and to provide a safe ITS. As a result, the scope of this review covered the XAI models used in ICV intrusion detection systems (IDSs), their taxonomies, and outstanding research problems. The results of the study show that XAI though in its infancy of application to ICV, is a promising research direction in the quest for improving the network efficiency of ICVs. The paper further reveals that XAI increased transparency will foster its acceptability in the automobile industry.
PDF
