Zika virus infection in semen: Effect on human reproduction

Unique among vector-borne flaviviruses, Zika virus can infect testis and male genital tract, can persist in semen for months after symptoms onset, and be sexually transmitted. In The Lancet Infectious Diseases, Guillaume Joguet and colleagues report alterations of sperm and testicular function in men with Zika virus infection, with potential effect on human reproduction. In this prospective longitudinal study, the authors detected viral RNA in the semen of 11 of 15 tested men, including five with persistent seminal shedding after viral clearance in blood. Notably, they were able to isolate infectious virus from motile spermatozoa obtained using semen separation methods that are generally used in assisted reproductive procedures. Semen alterations were observed, including a decreased sperm count and a concurrent increment of multiple sperm anomalies, especially in patients with Zika virus RNA-positive seminal specimens, while recovery was observed at day 120 post infection. In addition, inhibin \u3b2 concentrations decreased after infection, suggesting an impairment of Sertoli cells, which are key components of the blood\u2013testis barrier, produce immunoregulatory factors, and provide support to sperm cells during spermatogenesis. These findings suggest a direct effect of viral infection on the testis or epididymis with impairment of sperm development, in agreement with findings in animal models

Genome editing technologies to fight infectious diseases

Genome editing by programmable nucleases represents a promising tool that could be exploited to develop new therapeutic strategies to fight infectious diseases. These nucleases, such as zinc-finger nucleases, transcription activator-like effector nucleases, clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) and homing endonucleases, are molecular scissors that can be targeted at predetermined loci in order to modify the genome sequence of an organism. Areas covered: By perturbing genomic DNA at predetermined loci, programmable nucleases can be used as antiviral and antimicrobial treatment. This approach includes targeting of essential viral genes or viral sequences able, once mutated, to inhibit viral replication; repurposing of CRISPR-Cas9 system for lethal self-targeting of bacteria; targeting antibiotic-resistance and virulence genes in bacteria, fungi, and parasites; engineering arthropod vectors to prevent vector-borne infections. Expert commentary: While progress has been done in demonstrating the feasibility of using genome editing as antimicrobial strategy, there are still many hurdles to overcome, such as the risk of off-target mutations, the raising of escape mutants, and the inefficiency of delivery methods, before translating results from preclinical studies into clinical applications

Mapping and characterization of G-quadruplexes in Mycobacterium tuberculosis gene promoter regions

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), one of the top 10 causes of death worldwide in 2015. The recent emergence of strains resistant to all current drugs urges the development of compounds with new mechanisms of action. G-quadruplexes are nucleic acids secondary structures that may form in G-rich regions to epigenetically regulate cellular functions. Here we implemented a computational tool to scan the presence of putative G-quadruplex forming sequences in the genome of Mycobacterium tuberculosis and analyse their association to transcription start sites. We found that the most stable G-quadruplexes were in the promoter region of genes belonging to definite functional categories. Actual G-quadruplex folding of four selected sequences was assessed by biophysical and biomolecular techniques: all molecules formed stable G-quadruplexes, which were further stabilized by two G-quadruplex ligands. These compounds inhibited Mycobacterium tuberculosis growth with minimal inhibitory concentrations in the low micromolar range. These data support formation of Mycobacterium tuberculosis G-quadruplexes in vivo and their potential regulation of gene transcription, and prompt the use of G4 ligands to develop original antitubercular agents

Liver stiffness is not associated with short- and long-term plasma HIV RNA replication in immunocompetent patients with HIV infection and with HIV/HCV coinfection

Background:Human immunodeficiency virus (HIV) may be directly responsible for liver damage but there are contrasting data regarding the influence of detectable plasma viremia. We analyzed the influence of plasma HIV RNA (pHIV) detectability and of other clinical and viro-immunological variables on liver stiffness (LS) measurement in adult immunocompetent HIV-monoinfected patients and in patients coinfected with hepatitis C virus (HCV). Methods: Logistic regression analysis was performed using the value of LS>7.1 kPa as the dependent variable. A linear regression model was applied using LS measurement after log 10 transformation (lkpa) as the dependent variable and we analyzed the predicted values versus the observed lkpa values; pHIV was classified as detectable or undetectable in the 12- and 36-month study periods before LS measurement. Results: We studied 251 patients (178 with HIV monoinfection), most of whom were on antiviral treatment; 36-month study time was available for 154 subjects. The mean CD4+ cell count was 634 cells/mm3 in HIV-monoinfected patients and 606 cells/mm3 in coinfected patients. No difference in LS was found between patients with detectable or undetectable pHIV in either the 12- or the 36-month study period before transient elastography. The mean LS was higher in HIV/HCV coinfected patients (P<0.0001) than in the HIV-monoinfected subjects; lkpa was positively correlated with HCV coinfection (P<0.0001) and aspartate aminotransferase levels (P<0.0001). Detectable pHIV failed to reach significance. Eight HIV-monoinfected patients had a predicted LS measurement lower than the observed one, while eight patients had the opposite result. Conclusion: LS was not correlated with ongoing HIV replication during the 12- and 36-month study periods in immunocompetent HIV-monoinfected and HIV/HCV-coinfected patients

Reconstructing the recent West Nile virus lineage 2 epidemic in Europe and Italy using discrete and continuous phylogeography

West Nile virus lineage 2 (WNV-2) was mainly confined to sub-Saharan Africa until the early 2000s, when it was identified for the first time in Central Europe causing outbreaks of human and animal infection. The aim of this study was to reconstruct the origin and dispersion of WNV-2 in Central Europe and Italy on a phylodynamic and phylogeographical basis. To this aim, discrete and continuous space phylogeographical models were applied to a total of 33 newly characterised full-length viral genomes obtained from mosquitoes, birds and humans in Northern Italy in the years 2013-2015 aligned with 64 complete sequences isolated mainly in Europe. The European isolates segregated into two highly significant clades: a small one including three sequences and a large clade including the majority of isolates obtained in Central Europe since 2004. Discrete phylogeographical analysis showed that the most probable location of the root of the largest European clade was in Hungary a mean 12.78 years ago. The European clade bifurcated into two highly supported subclades: one including most of the Central/East European isolates and the other encompassing all of the isolates obtained in Greece. The continuous space phylogeographical analysis of the Italian clade showed that WNV-2 entered Italy in about 2008, probably by crossing the Adriatic sea and reaching a central area of the Po Valley. The epidemic then spread simultaneously eastward, to reach the region of the Po delta in 2013, and westward to the border area between Lombardy and Piedmont in 2014; later, the western strain changed direction southward, and reached the central area of the Po valley once again in 2015. Over a period of about seven years, the virus spread all over an area of northern Italy by following the Po river and its main tributaries

Current views on Zika virus vaccine development

Zika virus (ZIKV) is a mosquito-borne flavivirus, which was identified in 1947 in the Zika Forest of Uganda. The virus has emerged in the recent years and caused large human outbreaks in the Pacific area (Yap Island in 2007; French Polynesia in 2013 to 2014) and in the Americas (since late 2014). As of 8 June 2017, according to the Pan American Health Organization/World Health Organization, 48 countries in South America, Central America, and Caribbean reported ZIKV outbreaks, with a total of 212,545 confirmed cases of infection and 565,749 suspected cases. In addition, in 2016, Florida and Texas (USA) observed 225 autochthonous cases of ZIKV infection. The incidence was estimated as about 200 cases/100,000 population in countries like Brazil, Colombia, and Venezuela, where large and intense epidemic waves were registered during the first half of 2016. Although ZIKV transmission has significantly decreased in the region during the second half of 2016, most of the countries are still reporting cases of infection. Outsides the Americas, areas of ongoing intense transmission include countries in Asia (Singapore, Thailand, Vietnam, Malaysia, and the Philippines), Africa (Angola), and the South Pacific region (American Samoa)