ProBiS is a new method to identify the binding site of protein through local structural alignment against the nonredundant Protein Data Bank (PDB), which may result in unique findings compared to the energy-based, geometry-based, and sequence-based predictors. In this work, binding sites of Hemagglutinin (HA), which is an important target for drugs and vaccines in influenza treatment, have been revisited by ProBiS. For the first time, the identification of conserved binding sites by local structural alignment across all subtypes and strains of HA available in PDB is presented. ProBiS finds three distinctive conserved sites on HA's structure (named Site 1, Site 2, and Site 3). Compared to other predictors, ProBiS is the only one that accurately defines the receptor binding site (Site 1). Apart from that, Site 2, which is located slightly above the TBHQ binding site, is proposed as a potential novel conserved target for membrane fusion inhibitor. Lastly, Site 3, located around Helix A at the stem domain and recently targeted by cross-reactive antibodies, is predicted to be conserved in the latest H7N9 China 2013 strain as well. The further exploration of these three sites provides valuable insight in optimizing the influenza drug and vaccine development.
Duck Tembusu virus (DTMUV), a newly identified flavivirus, has rapidly spread to China, Malaysia and Thailand. The potential threats to public health have been well-highlighted; however its virulence and pathogenesis remain largely unknown. Here, by using reverse genetics, a recombinant chimeric DTMUV based on Japanese encephalitis live vaccine strain SA14-14-2 was obtained by substituting the corresponding prM and E genes (named ChinDTMUV). In vitro characterization demonstrated that ChinDTMUV replicated efficiently in mammalian cells with small-plaque phenotype in comparison with its parental viruses. Mouse tests showed ChinDTMUV exhibited avirulent phenotype in terms of neuroinvasiveness, while it retained neurovirulence from its parental virus DTMUV. Furthermore, immunization with ChinDTMUV was evidenced to elicit robust IgG and neutralizing antibody responses in mice. Overall, we successfully developed a viable chimeric DTMUV, and these results provide a useful platform for further investigation of the pathogenesis of DTMUV and development of a live attenuated DTMUV vaccine candidate.
Antibody phage display panning involves the enrichment of antibodies against specific targets by affinity. In recent years, several new methods for panning have been introduced to accommodate the growing application of antibody phage display. The present work is concerned with the application of streptavidin mass spectrometry immunoassay (MSIA™) Disposable Automation Research Tips (D.A.R.T's®) for antibody phage display. The system was initially designed to isolate antigens by affinity selection for mass spectrometry analysis. The streptavidin MSIA™ D.A.R.T's® system allows for easy attachment of biotinylated target antigens on the solid surface for presentation to the phage library. As proof-of-concept, a domain antibody library was passed through the tips attached with the Hemolysin E antigen. After binding and washing, the bound phages were eluted via standard acid dissociation and the phages were rescued for subsequent panning rounds. Polyclonal enrichment was observed for three rounds of panning with five monoclonal domain antibodies identified. The proposed method allows for a convenient, rapid and semi-automated alternative to conventional antibody panning strategies.
Forty-five years ago a naturally attenuated tick-borne flavivirus, Langat (LGT) strain TP21, was recovered from ticks in Malaysia. Subsequently, it was tested as a live attenuated vaccine for virulent tick-borne encephalitis viruses. In a large clinical trial its attenuation was confirmed but there was evidence of a low level of residual virulence. Thirty-five years ago further attenuation of LGT TP21 was achieved by multiple passages in eggs to yield mutant E5. To study the genetic determinants of the further attenuation exhibited by E5 and to allow us to manipulate the genome of this virus for the purpose of developing a satisfactory live attenuated tick-borne flavivirus vaccine, we recovered infectious E5 virus from a full-length cDNA clone. The recombinant E5 virus (clone 651) recovered from a full-length infectious cDNA clone was more attenuated in immunodeficient mice than that of its biologically derived E5 parent. Increase in attenuation was associated with three amino acid substitutions, two located in the structural protein E and one in nonstructural protein NS4B. Subsequently an even greater degree of attenuation was achieved by creating a viable 320 nucleotide deletion in the 3'-noncoding region of infectious full-length E5 cDNA. This deletion mutant was not cytopathic in simian Vero cells and it replicated to lower titer than its E5-651 parent. In addition, the E5 3' deletion mutant was less neuroinvasive in SCID mice than its E5-651 parent. Significantly, the deletion mutant proved to be 119,750 times less neuroinvasive in SCID mice than its progenitor, LGT strain TP21. Despite its high level of attenuation, the E5 3' deletion mutant remained highly immunogenic and intraperitoneal (ip) inoculation of 10 PFU induced complete protection in Swiss mice against subsequent challenge with 2000 ip LD50 of the wild-type LGT TP21.
The discovery that certain high-risk strains of human papillomavirus (HR-HPV) cause nearly 100% of invasive cervical cancer has spurred a revolution in cervical cancer prevention by promoting the development of viral vaccines. Although the efficacy of these vaccines has already been demonstrated, a complete understanding of viral latency and natural immunity is lacking, and solving these mysteries could help guide policies of cervical cancer screening and vaccine use. Here, we examine the epidemiological and biological understanding of the natural history of HPV infection, with an eye toward using these studies to guide the implementation of cervical cancer prevention strategies.
We had examined the immunogenicity of a series of plasmid DNAs which include neuraminidase (NA) and nucleoprotein (NP) genes from avian influenza virus (AIV). The interleukin-15 (IL-15) and interleukin-18 (IL-18) as genetic adjuvants were used for immunization in combination with the N1 and NP AIV genes. In the first trial, 8 groups of chickens were established with 10 specific-pathogen-free (SPF) chickens per group while, in the second trial 7 SPF chickens per group were used. The overall N1 enzyme-linked immunosorbent assay (ELISA) titer in chickens immunized with the pDis/N1+pDis/IL-15 was higher compared to the chickens immunized with the pDis/N1 and this suggesting that chicken IL-15 could play a role in enhancing the humoral immune response. Besides that, the chickens that were immunized at 14-day-old (Trial 2) showed a higher N1 antibody titer compared to the chickens that were immunized at 1-day-old (Trial 1). Despite the delayed in NP antibody responses, the chickens co-administrated with IL-15 were able to induce earlier and higher antibody response compared to the pDis/NP and pDis/NP+pDis/IL-18 inoculated groups. The pDis/N1+pDis/IL-15 inoculated chickens also induced higher CD8+ T cells increase than the pDis/N1 group in both trials (P<0.05). The flow cytometry results from both trials demonstrated that the pDis/N1+pDis/IL-18 groups were able to induce CD4+ T cells higher than the pDis/N1 group (P<0.05). Meanwhile, pDis/N1+pDis/IL-18 group was able to induce CD8+ T cells higher than the pDis/N1 group (P<0.05) in Trial 2 only. In the present study, pDis/NP was not significant (P>0.05) in inducing CD4+ and CD8+ T cells when co-administered with the pDis/IL-18 in both trials in comparison to the pDis/NP. Our data suggest that the pDis/N1+pDis/IL-15 combination has the potential to be used as a DNA vaccine against AIV in chickens.