Mutational analysis of the internal membrane proximal domain of the HIV glycoprotein C-terminus

HIV-1 env gene mutations outside the targeting probe affects IPDA efficiency

The intact proviral DNA assay (IPDA) based on droplet digital PCR was developed to identify intact proviral DNA and quantify HIV-1 latency reservoirs in patients infected with HIV-1. However, the genetic characteristics of different HIV-1 subtypes are non-consistent due to their high mutation and recombination rates. Here, we identified that the IPDA based on the sequences features of an HIV-1 subtype could not effectively detect different HIV-1 subtypes due to the high diversity of HIV-1. Furthermore, we demonstrated that mutations in env gene outside the probe binding site affect the detection efficiency of IPDA. Since mutations in env gene outside the probe binding site may also lead to the formation of stop codons, thereby preventing the formation of viruses and ultimately overestimating the number of HIV-1 latency reservoirs, it is important to address the effect of mutations on the IPDA.

Let It Go: HIV-1 cis-Acting Repressive Sequences

After human immunodeficiency virus type 1 (HIV-1) was identified in the early 1980s, intensive work began to understand the molecular basis of HIV-1 gene expression. Subgenomic HIV-1 RNA regions, spread throughout the viral genome, were described to have a negative impact on the nuclear export of some viral transcripts. Those studies revealed an intrinsic RNA code as a new form of nuclear export regulation. Since such regulatory regions were later also identified in other viruses, as well as in cellular genes, it can be assumed that, during evolution, viruses took advantage of them to achieve more sophisticated replication mechanisms. Here, we review HIV-1 cis-acting repressive sequences that have been identified, and we discuss their possible underlying mechanisms and importance. Additionally, we show how current bioinformatic tools might allow more predictive approaches to identify and investigate them.

Behind the scenes of HIV-1 replication: Alternative splicing as the dependency factor on the quiet

Alternative splicing plays a key role in the HIV-1 life cycle and is essential to maintain an equilibrium of mRNAs that encode viral proteins and polyprotein-isoforms. In particular, since all early HIV-1 proteins are expressed from spliced intronless and late enzymatic and structural proteins from intron containing, i.e. splicing repressed viral mRNAs, cellular splicing factors and splicing regulatory proteins are crucial for the replication capacity. In this review, we will describe the complex network of cis-acting splicing regulatory elements (SREs), which are mainly localized in the neighbourhoods of all HIV-1 splice sites and warrant the proper ratio of individual transcript isoforms. Since SREs represent binding sites for trans-acting cellular splicing factors interacting with the cellular spliceosomal apparatus we will review the current knowledge of interactions between viral RNA and cellular proteins as well as their impact on viral replication. Finally, we will discuss potential therapeutic approaches targeting HIV-1 alternative splicing.