Zika virus (ZIKV, genus Flavivirus) has emerged as a major mosquito-transmitted human pathogen, with recent outbreaks associated with an increased incidence of neurological complications, particularly microcephaly and the Guillain–Barré syndrome. Because the virus has only very recently emerged as an important pathogen, research is being hampered by a lack of reliable molecular tools. Here we report an infectious cDNA (icDNA) clone for ZIKV isolate BeH819015 from Brazil, which was selected as representative of South American ZIKV isolated at early stages of the outbreak. icDNA clones were assembled from synthetic DNA fragments corresponding to the consensus sequence of the BeH819015 isolate. Virus rescued from the icDNA clone had properties identical to a natural ZIKV isolate from South America. Variants of the clone-derived virus, expressing nanoluciferase, enhanced green fluorescent or mCherry marker proteins in both mammalian and insect cells and being genetically stable for multiple in vitro passages, were obtained. A ZIKV subgenomic replicon, lacking a prM- and E glycoprotein encoding region and expressing a Gaussia luciferase marker, was constructed and shown to replicate both in mammalian and insect cells. In the presence of the Semliki Forest virus replicon, expressing ZIKV structural proteins, the ZIKV replicon was packaged into virus-replicon particles. Efficient reverse genetic systems, genetically stable marker viruses and packaged replicons offer significant improvements for biological studies of ZIKV infection and disease, as well as for the development of antiviral approaches.
CD59 protein functions as a negative regulator of the terminal pathway of the complement system by binding to the C8/C9 factors. To date, little is known about the role of CD59 in coronavirus infectious bronchitis virus (IBV) infection. In this study, we discovered that CD59 was downregulated in IBV-infected cells and was associated with IBV virions. This association protected IBV particles from antibody-dependent complement-mediated lysis. IBV titres in the supernatant were significantly increased when CD59 proteins were overexpressed in cells followed by IBV infection, and this observation was further supported by knockdown or cleavage of CD59. Because no considerable change in IBV N protein and viral RNA levels was detected in total cell lysates prepared from the overexpression, knockdown or cleavage of CD59 groups, our data indicated that CD59 was involved in IBV particle release and that IBV had evolved a mechanism to utilize CD59 to evade complement-mediated destruction.
Zika virus (ZIKV) is a mosquito-borne flavivirus and has historically been reported to cause mild symptomatic diseases during human infections. More recently, the explosion of microcephaly among infants born to ZIKV-infected women has made ZIKV a global public health concern. While ZIKV causes acute human diseases, infections of vector mosquitoes are basically non-pathogenic, allowing persistent infections and conferring lifelong ability to transmit the virus. Recent studies have revealed that DNA forms of arboviral RNA genomes play a significant role in viral persistence in mosquitoes. We have initiated experiments to determine whether ZIKV generates viral DNA (vDNA) forms following infection in mosquitoes. Here we show that vDNAs are generated following ZIKV infection both in mosquito cell cultures and in its primary vector Aedes aegypti. vDNA formation is more extensive in RNA interference (RNAi)-deficient Aedes albopictus-derived C6/36 cells compared to RNAi-proficient mosquito cells. In addition, vDNAs are generated via multiple template-switching events.
Porcine sapeloviruses (PSVs) are widely distributed in pig populations; however, little information on their evolutionary history and the mechanisms driving their divergence is available. Therefore, in the present study, 241 fecal samples and 91 intestinal contents collected from pigs at 26 farms in Hunan, China, were tested for the presence of PSVs. The overall PSV positivity rate was 46.39 %, with a particularly high infection rate detected in nursery and fattening pigs. A total of 29 PSV strains (PSV-HuNs) were isolated, with these showing high genetic diversity based on phylogenetic and pairwise distance analyses of the capsid-protein gene sequences. Incongruence between phylognetic trees of the capsid-protein and 3CD regions indicated frequent recombination within the PSV-HuNs, and a putative recombinant hotspot near the 3′ end of the P1 region was identified. Our results suggested that recombination played an important role in driving PSV genetic diversity and evolution.