Herpes Simplex Virus Is Equipped with RNA- and Protein-Based Mechanisms To Repress Expression of ATRX, an Effector of Intrinsic Immunity

Intrinsic immunity is a first-line intracellular defense against virus infection, and viruses have evolved mechanisms to counteract it. During herpes simplex virus (HSV) infection, nuclear domain 10 (ND10) components localize adjacent to incoming viral genomes and generate a repressive environment for viral gene expression. Here, we found that the ND10 component, alpha-thalassemia/mental retardation syndrome X-linked (ATRX) protein, is predicted to be a target of HSV-1 miR-H1 and HSV-2 miR-H6. These microRNAs (miRNAs) share a seed sequence and are abundant during lytic infection. Mimics of both miRNAs could deplete endogenous ATRX, and an miR-H1 mimic could repress the expression of a reporter linked to the 3' untranslated region of ATRX mRNA, identifying a cellular mRNA targeted by an HSV miRNA. Interestingly, ATRX protein and its mRNA were depleted in cells lytically infected with HSV, and ATRX protein was also depleted in cells infected with human cytomegalovirus. However, infection with an HSV-1 mutant lacking miR-H1 still resulted in ATRX depletion. This depletion was sensitive to a proteasome inhibitor and was largely ablated by a deletion of the gene encoding the immediate-early ICP0 protein. Additionally, a deletion of the gene encoding the tegument protein Vhs ablated most of the depletion of ATRX mRNA. Thus, HSV is equipped with multiple mechanisms to limit the expression of ATRX. As ATRX is implicated in repression of lytic viral gene expression, our results suggest roles for these different mechanisms during various phases of HSV infection.     

Factors Affecting Domestic Water Consumption in Rural Households upon Access to Improved Water Supply: Insights from the Wei River Basin,China

Comprehensively understanding water consumption behavior is necessary to design efficient and effective water use strategies. Despite global efforts to identify the factors that affect domestic water consumption, those related to domestic water use in rural regions have not been sufficiently studied, particularly in villages that have gained access to improved water supply. To address this gap, we investigated 247 households in eight villages in the Wei River Basin where three types of improved water supply systems are implemented. Results show that domestic water consumption in liters per capita per day was significantly correlated with water supply pattern and vegetable garden area, and significantly negatively correlated with family size and age of household head. Traditional hygiene habits, use of water appliances, and preference for vegetable gardening remain dominant behaviors in the villages with access to improved water supply. Future studies on rural domestic water consumption should pay more attention to user lifestyles (water appliance usage habits, outdoor water use) and cultural backgrounds (age, education).     

Acyclovir-resistant, pathogenic herpesviruses

In herpes simplex virus, the simplest path to resistance to the drug acyclovir is a mutation that knocks out the enzyme thymidine kinase. Such mutants are highly attenuated in mouse models of viral pathogenesis, but have been reported to be associated with severe disease in immunocompromised patients. This review discusses possible resolutions of this paradox.     

The herpes simplex virus type 1 UL42 gene product: a subunit of DNA polymerase that functions to increase processivity.

Genetic experiments have shown that the products of the herpes simplex virus type 1 (HSV-1) DNA polymerase (UL30) and UL42 genes are both required for viral DNA replication, and a number of studies have suggested that these two proteins specifically interact. We have confirmed and extended these findings. The viral DNA polymerase from HSV-1-infected cells has been purified as a complex containing equimolar quantities of the UL30 (Pol, the catalytic subunit) and UL42 polypeptides. Sedimentation and gel filtration analyses of this complex are consistent with the idea that the complex consists of a heterodimer of Pol and UL42. A complex with identical physical and functional properties was also purified from insect cells coinfected with recombinant baculoviruses expressing the two polypeptides. Therefore, the formation of the Pol-UL42 complex does not require the participation of any other HSV-encoded protein. We have compared the catalytic properties of the Pol-UL42 complex with those of the isolated subunits of the enzyme purified from recombinant baculovirus-infected insect cells. The specific activity of the catalytic subunit alone was nearly identical to that of the complex when assayed on activated DNA. When assayed on a defined template such as singly primed M13 DNA, however, the combination of Pol and UL42 utilized fewer primers and formed larger products than Pol alone. Template challenge experiments demonstrated that the Pol-UL42 complex was more highly processive than Pol alone. Our data are consistent with the idea that the UL42 polypeptide is an accessory subunit of the DNA polymerase that acts to increase the processivity of polymerization.     

Phenotypic effects of short-range and aberrant transposition in Antirrhinum majus

We describe two novel ways in which changes in gene expression in Antirrhinum majus may arise as a consequence of the Tam3 transposition mechanism. One involves excision of Tam3 from the nivea gene promoter and insertion of two new Tam3 copies 3.4 kb and 2.1 kb away, on either side of the excision site. One of the new insertions is in the nivea coding region and completely blocks production of an active gene product. This allele probably arose by a symmetrical double transposition, following chromosome replication. The second case involves a small deletion at one end of Tam3 in the pallida gene, flanked by a sequence typical of a Tam3 excision footprint. This suggests that the end of Tam3 was cleaved at an early step in an attempted transposition and re-ligated back to its original flanking sequence. The alteration restores some expression to the pallida gene, suggesting that the ends of the intact Tam3 element contain components which can actively inhibit gene expression. The implications of these findings for the mechanism of Tam3 transposition and for the effects of Tam3 on host gene expression are discussed.