Transcriptional effects of superinfection in HIV chronically infected T cells: studies in dually infected clones

The effects of MAPK p38α on AZT resistance against reactivating HIV-1 replication in ACH2 cells

Antiretroviral therapy (ART) has remarkably decreased HIV-related mortality. However, drug-resistant HIV variants pose a potential threat to the long-term success of ART. Both HIV mutants and host factors can cause HIV drug resistance. Using susceptible ACH2 cells chronically infected with HIV-1, we examined the effects of MAPK p38α on AZT resistance against reactivating HIV-1 replication that can be activated by HIV-1 superinfection. We found that HIV-1 superinfection induced more viral production, which was diminished by p38 inhibitor, SB203580, and by AZT in cells infected with non-AZT-resistant HIV-1 strain MN. p38α expression can resist action of AZT in inhibition of HIV-1 replication with increased expression of transcription factor, NF-ĸBp65, SP1, and c-Fos through activation of TCR-related pathways with upregulation of CD3, TCRα, TCRβ, Zap-70, PKC, PLCγ1, GRB2, and PI3K/Akt expression. In HIV-1 MN superinfection under AZT treatment, expression of p38α led to HIV vif expression and inhibited APOBEC3G expression. We also investigated effects of p38α on gp130/JAK-STAT pathways, in which p38α increased expression of protein, gp130, EGFR, Jak2, STAT1, STAT3, STAT5, ras, and TF. p38α could induce apoptotic pathways with upregulation of Fas, FADD, Caspase-8, p53, and Bax, and downregulation of Bcl2 expression. These results indicate that p38α plays a positive role in reactivation of viral replication from HIV-1 latent infection and leads to HIV-1 AZT resistance. In conclusion, MAPKp38α can activate HIV-1 replication inhibited by AZT from HIV-1 latent infection and may be used as a latency reversal agent. The activation involves induction of several cell signaling pathways that are required for HIV-1 replication, which may be integrated into future viral remission strategies.

Evidence of ongoing replication in a human immunodeficiency virus type 1 persistently infected cell line

Human immunodeficiency virus type 1 (HIV-1) persistently infected cell lines are characterized by the continuous viral production without cytopathic effect. However, it is not completely clear if this production is contributed only by viral transcription or also by new cycles of viral replication. We studied an HIV-1 persistently infected cell line, designated H61-D, providing evidence of new replication cycles as sustained by: (i) a decrease in viral production, measured by p24 protein, after treatment of the culture with 3'-azydo-3'-deoxythymydine; (ii) detection of new integration events in the course of cell culture, and (iii) finding of two-long-terminal repeat circles in the cells. H61-D cells were not infected by cell-free virus, but infection was possible by co-culture with another productive-infected cell line. In conclusion, ongoing viral replication is taking place in H61-D persistent cells and new infections are mediated by a cell-to-cell spread mechanism.

Dual lentivirus infection potentiates neuroinflammation and neurodegeneration: viral copassage enhances neurovirulence

Infection by multiple lentiviral strains is recognized as a major driving force in the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic, but the neuropathogenic consequences of multivirus infections remain uncertain. Herein, we investigated the neurovirulence and underlying mechanisms of dual lentivirus infections with distinct viral strains. Experimental feline immunodeficiency virus (FIV) infections were performed using cultured cells and an in vivo model of AIDS neuropathogenesis. Dual infections were comprised of two FIV strains (FIV-Ch and FIV-PPR) as copassaged or superinfected viruses, with subsequent outcome analyses of host immune responses, viral load, neuropathological features, and neurobehavioral performance. Dual infections of feline macrophages resulted in greater IL-1beta (interleukin-1beta), TNF-alpha (tumor necrosis factor alpha), and IDO (indoleamine 2,3-dioxygenase) expression and associated neurotoxic properties. FIV coinfection and sequential superinfection in vivo also induced greater IL-1beta, TNF-alpha, and IDO expression in the basal ganglia (BG) and cortex (CTX), compared to the monovirus- and mock-infected groups, although viral loads were similar in single virus- and dual virus-infected animals. Immunoblot analyses disclosed lower synaptophysin immunoreactivity in the CTX resulting from FIV super- and coinfections. Cholinergic and GABAergic neuronal injury was evident in the CTX of animals with dual FIV infections. With increased glial activation and neuronal loss in dual FIV-infected brains, immunohistochemical analysis also revealed elevated detection of cleaved caspase-3 in dysmorphic neurons, which was associated with worsened neurobehavioral abnormalities among animals infected with the copassaged viruses. Dual lentivirus infections caused an escalation in neuroinflammation and ensuing neurodegeneration, underscoring the contribution of infection by multiple viruses to neuropathogenesis.

HIV superinfection in the era of increased sexual risk-taking

Recent reports have documented increases in unprotected intercourse (UI) and sexually transmitted diseases (STDs) among men who have sex with men (MSM) and other at-risk populations. A further consequence of persons living with HIV engaging in unprotected intercourse or shared parenteral exposures with seroconcordant partners is HIV recombination and superinfection, possibly with a drug-resistant or more pathogenic virus. The epidemiologic, clinical, and therapeutic implications of recent case reports confirming superinfection in persons living with HIV, as well as research priorities aimed at providing a more thorough understanding of the consequences of unprotected sex among HIV-infected people, are explored here.

Human immunodeficiency virus superinfection and recombination: current state of knowledge and potential clinical consequences

Superinfection with multiple strains or subtypes of the human and simian immunodeficiency viruses has been documented. Recent increases in the prevalences of both unprotected anal intercourse and sexually transmitted diseases among men who have sex with men indicate that these men continue to practice unsafe sex and, therefore, are at risk for superinfection with the human immunodeficiency virus (HIV). Recurrent exposure to HIV among seropositive individuals who engage in high-risk behaviors can have serious consequences, because superinfection is a necessary first step for viral recombination to occur. Recombination may produce more virulent viruses, drug-resistant viruses, or viruses with altered cell tropism. Additionally, recombinant viruses and superinfection can accelerate disease progression and increase the likelihood of sexual transmission by increasing virus load in the blood and genital tract. The extent of superinfection and recombination in persons living with HIV is unknown. The implications of HIV superinfection and the generation of recombinant viruses are discussed.

Cofactors for HIV disease progression in a cohort of homosexual and bisexual men

To evaluate cofactors for progression of HIV infection, the authors identified 370 men with well-defined seroconversion dates and cofactor data among participants in the San Francisco City Clinic Cohort (SFCCC). Postseroconversion substance use, sexual behavior, and sexually transmitted diseases were assessed using multivariate proportional hazards models. Weekly use of hallucinogens strongly and independently predicted death (relative hazard [RH], 2.59; 95% confidence interval [CI], 1.56-4.28), as well as diagnosis of AIDS; weekly cocaine use also predicted mortality. Receptive anal intercourse with ejaculation was independently associated with mortality risk (RH, 1.45; 95% CI, 1.02-2.04) and AIDS. The associations of accelerated progression with weekly use of recreational drugs and unprotected receptive anal intercourse need to be confirmed in other prospective cohorts.

Recombination in HIV: an important viral evolutionary strategy

Human immunodeficiency virus (HIV) is a diploid virus: each virion carries two complete RNA genomic strands. Homologous recombination can occur when a cell is coinfected with two different but related strains. Naturally occurring recombinant HIV strains have been found in infected patients in regions of the world where multiple genotypic variants cocirculate. One recombinant HIV strain has spread rapidly to millions of persons in Southeast Asia. Recombination is a mechanism whereby high level and multidrug-resistant strains may be generated in individual treated patients. Recombination also poses theoretical problems for the development of a safe HIV vaccine. Certain features of HIV replication, such as syncytium formation and transactivation, may be best understood as components of a sexual reproductive cycle. Recombination may be an important HIV evolutionary strategy.