A Genome-Wide Comparative Evolutionary Analysis of Herpes Simplex Virus Type 1 and Varicella Zoster Virus

Herpes simplex virus type 1 (HSV-1) and varicella zoster virus (VZV) are closely related viruses causing lifelong infections. They are typically associated with mucocutaneous or skin lesions, but may also cause severe neurological or ophthalmic diseases, possibly due to viral- and/or host-genetic factors. Although these viruses are well characterized, genome-wide evolutionary studies have hitherto only been presented for VZV. Here, we present a genome-wide study on HSV-1. We also compared the evolutionary characteristics of HSV-1 with those for VZV. We demonstrate that, in contrast to VZV for which only a few ancient recombination events have been suggested, all HSV-1 genomes contain mosaic patterns of segments with different evolutionary origins. Thus, recombination seems to occur extremely frequent for HSV-1. We conclude by proposing a timescale for HSV-1 evolution, and by discussing putative underlying mechanisms for why these otherwise biologically similar viruses have such striking evolutionary differences

Schmallenberg virus infection of ruminants: challenges and opportunities for veterinarians

François Claine, Damien Coupeau, Laetitia Wiggers, Benoît Muylkens, Nathalie Kirschvink Veterinary Department, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), Namur, Belgium Abstract: In 2011, European ruminant flocks were infected by Schmallenberg virus (SBV) leading to transient disease in adult cattle but abortions and congenital deformities in calves, lambs, and goat kids. SBV belonging to the Simbu serogroup (family Bunyaviridae and genus Orthobunyavirus) was first discovered in the same region where bluetongue virus serotype 8 (BTV-8) emerged 5 years before. Both viruses are transmitted by biting midges (Culicoides spp.) and share several similarities. This paper describes the current knowledge of temporal and geographical spread, molecular virology, transmission and susceptible species, clinical signs, diagnosis, prevention and control, impact on ruminant health, and productivity of SBV infection in Europe, and compares SBV infection with BTV-8 infection in ruminants. Keywords: Schmallenberg virus, Europe, ruminants, revie

Schmallenberg virus among female lambs, Belgium, 2012

Reemergence of Schmallenberg virus (SBV) occurred among lambs (n = 50) in a sheep flock in Belgium between mid-July and mid-October 2012. Bimonthly assessment by quantitative reverse transcription PCR and seroneutralization demonstrated that 100% of lambs were infected. Viremia duration may be longer in naturally infected than in experimentally infected animals

Characterization of messenger RNA termini in Schmallenberg virus and related Simbuviruses

Schmallenberg virus (SBV) is an emerging arbovirus infecting ruminants in Europe. SBV belongs to the Bunyaviridae family within the Simbu serogroup. Its genome comprises three segments, small (S), medium (M) and large (L), that together encode six proteins and contain NTRs. NTRs are involved in initiation and termination of transcription and in genome packaging. This study explored the 3′ mRNA termini of SBV and related Simbuviruses. In addition, the 5′ termini of SBV messenger RNA (mRNA) were characterized. For the three SBV segments, cap-snatching was found to initiate mRNA transcription both in vivo and in vitro. The presence of extraneous nucleotides between host RNA leaders and the viral termini fits with the previously described prime-and-realign theory. At the 3′ termini, common features were identified for SBV and related Simbuviruses. However, different patterns were observed for the termini of the three segments from the same virus type.</jats:p

In vivo and in vitro identification of a hypervariable region in Schmallenberg virus

Detected for the first time in 2011, Schmallenberg virus (SBV) is an orthobunyavirus of the Simbu serogroup that caused a large outbreak in European ruminants. In a tight time frame, data have been obtained on SBV epidemiology and the clinical pictures associated with this new viral infection, but little information is available on the molecular biology of SBV. In this study, SBV sequence variability was characterized from the central nervous system of two stillborn lambs in a naturally infected herd. A hypervariable region (HVR) was detected in the N-terminal region of the SBV Gc glycoprotein through sequencing and analysis of the two full-length genomes representative of intra-herd SBV dissemination. In vitro growth assays coupled with full-length genome sequencing were performed on the two isolates after successive cellular passages, showing an in vitro adaptation of SBV and mutation accumulation inside the HVR in the absence of immune selective pressure.</jats:p

Setting up a SPF Chicken Model for the Pathotyping of West Nile Virus (WNV) Strains

Birds play a central role in WNV epidemiology by spreading and amplifying thevirus. Increasing numbers of WNV isolates are detected in Europe, and the virulenceof these genetically variable isolates is not well characterized for birds.Therefore, we investigated whether SPF chickens could be a valuable avian modelfor the pathotyping of WNV strains. One-day-old SPF chickens were inoculatedsubcutaneously (SC) or intracerebrally (IC) with four lineage 1 WNV strains(Is98, It2008, Fr2000 or Kunjin) and were daily clinically monitored for 2 weeksafter infection. Additionally, one-day-old SPF chickens were SC inoculated,and one-week-old SPF chickens were SC or IC inoculated with twoEuro-Mediterranean isolates, Is98 and Fr2000, to sample blood and feathers atregular time points. These samples were analysed by WN NS2a-specific rRT-PCRand WN NS1 antigen-capture ELISA that were developed for the purpose of thisstudy. Differences in strain virulence were evidenced after IC inoculation of oneday-old SPF chickens, with Is98 eliciting the highest mortality rates and Kunjinthe lowest ones, while lethality of Fr2000 and It2008 was intermediate. Neitherviral load in sera and feathers nor NS1 antigen in the serum correlated with thedifferential pathogenicity of Is98 and Fr2000. However, irrespective of the inoculatedstrain, younger chickens showed higher and longer-lasting viremias thanolder chickens. In all experimental groups, the detection window for viral RNA infeathers lasted up to 14 dpi. Altogether, the data presented in this study show thatWNV strain virulence can be discriminated in a one-day-old SPF chicken modelon the basis of mortality rates, while viremia and viral load in feathers appear tobe age dependent rather than strain dependent