No abstract

No abstract

BackgroundHantaviruses cause acute hemorrhagic fever with renal syndrome (HFRS). Currently, several types of inactivated HFRS vaccines are widely used, however the limited ability of these immunogen to elicit neutralizing antibodies restricts vaccine efficacy. Development of an effective vaccine to overcome this weakness is must.MethodsIn the present study, a recombinant pseudotyped lentivirus bearing the hantaan virus (HTNV) envelope glycoproteins (GP), rLV-M, was constructed. C57BL/6 mice were immunized with the rLV-M and a series of immunological assays were conducted to determine the immunogenicity of the recombinant pseudotyped lentivirus. The humoral and cell-mediated immune responses induced by rLV-M were compared with those of the inactivated HFRS vaccine.ResultsIndirect immunofluorescence assay (IFA) showed the rLV-M expressed target proteins in HEK-293cells. In mice, the rLV-M efficiently induced GP-specific humoral responses and protection against HTNV infection. Furthermore, the rLV-M induced higher neutralizing antibody titers than the inactivated HFRS vaccine control.ConclusionsThe results indicated the potential of using a pseudotyped lentivirus as a delivery vector for a hantavirus vaccine immunogen.

No abstract

No abstract

Persistent high fever is one typical clinical symptom of hemorrhagic fever with renal syndrome (HFRS) and circulating interleukin-1β (IL-1β) is elevated throughout HFRS. The mechanisms responsible for viral induction of IL-1β secretion are unknown. In the present study, Hantaan virus (HTNV) induced the secretion of IL-1β in the human monocytic cell line THP-1. Induction of IL-1β by HTNV relies on the activation of caspase-1. Small hairpin RNA knockdown in HTNV-infected THP-1 cells indicated that nucleotide-binding domain, leucine-rich repeat containing protein 3 (NLRP3) recruits the adaptor apoptosis-associated speck-like protein and caspase-1 to form an NLRP3 inflammasome complex, crucial for the induction of IL-1β. In HTNV-infected THP-1 cells, reactive oxygen species release, but not extracellular adenosine triphosphate, was crucial for IL-1β production. In conclusion, Hantavirus induces the formation of the NLRP3 inflammasome in THP-1 cells and this may be responsible for the elevated IL-1β levels in HFRS patients.

The N-myc downstream-regulated gene-1 (NDRG1) has recently been proposed as a metastasis suppressor, but its precise role remains unclear. To investigate whether NDRG1 can indeed influence the metastasis progress, expression of endogenous NDRG1 was knocked down in human AGS gastric adenocarcinoma cells using RNA interference. Stable NDRG1 "silenced" transfectants showed similar growth rates as their control counterparts. By contrast, invasive ability in Matrigel invasion activity and Gelatinolytic activity by matrix metalloproteinase-2 (MMP-2) were markedly increased in NDRG1 "silenced" cells. Moreover, re-expression of NDRG1 by recombinant adenovirus Ad-NDRG1 in NDRG1 "silenced" cells inhibited the increased invasive ability. Further study, we found the induction of MMP-2 by downregulation of NDRG1 was mediated by MT1-MMP. Altogether, our results imply that NDRG-1 could play a key role in the regulation of cellular invasion and metastasis, which may involve the upregulation of matrix metalloproteinases.

Hantavirus glycoprotein Gc is one of the main components that contribute to the generation of humoral immune responses, while the nucleocapsid protein (NP) is involved in cellular immune responses through the induction of antibody-dependent cytotoxic T cells. In this study, a chimeric gene, GcS0.7, which encodes a fusion protein containing Gc and truncated NP, was constructed as a candidate for Hantaan virus (HTNV) vaccine development. The chimeric gene was cloned into an adenoviral vector in conjunction with the powerful hybrid cytomegalovirus (CMV) enhancer/chicken β-actin (CAG) promoter or the woodchuck hepatitis virus (WHV) post-transcriptional regulatory element (WPRE), or both. Both elements increased the expression level of the fusion protein. The rAd-GcS0.7-pCAG group demonstrated the highest fusion protein expression level, with a 2.3-fold increase compared with the unmodified adenoviral vector. To further evaluate the humoral and cellular immunity induced by the recombinant adenovirus, the antibody titers, interferon (IFN)-γ secretion level and cytotoxic T cell ratio were detected in immunized mice. The strongest HTNV‑specific humoral and cellular immune responses were detected in the rAd-GcS0.7‑pCAG group. The immunogenicity of these recombinant adenoviruses was compared with that of the inactivated vaccine through a series of immunological assays. In terms of the cellular immune responses, the rAd-GcS0.7-pCAG group even exceeded those induced by the vaccine control. The CAG hybrid promoter improved not only the expression level, but also the immunogenicity of the fusion protein, and may thus provide a promising strategy for HTNV vaccine research.