No abstract

We have undertaken by biochemical and immunological experiments to locate the region of the matrix (M,) protein responsible for down-regulating endogenous transcription of A/WSNI33 influenza virus. A more refined map of the antigenic determinants of the M, protein was obtained by binding of epitope-specific monoclonal antibodies (MAbs) to chemically cleaved fragments. Epitope 2-specific MAb 289/4 and MAb 7E5 reverse transcription inhibition by M, protein and react with a 4-kilodalton cyanogen bromide fragment extending from amino acid Gly-129 to Gln-164. Anti-idiotype serum immunoglobulin G prepared in rabbits immunized with MAb 289/4 or MAb 7E5 mimicked the action of M, protein by inhibiting transcription in vitro of influenza virus ribonucleoprotein cores. This transcription-inhibition activity of anti-MAb 7E5 immunoglobulin G and anti-MAb 289/4 immunoglobulin G could be reversed by MAb 7E5 and MAb 289/4 or could be removed by MAb 7E5-Sepharose affinity chromatography. Transcription of influenza virus ribonucleoprotein was inhibited by one of three synthetic oligopeptides, a nonodecapeptide SP3 with an amino acid sequence corresponding to Pro-90 through Thr-108 of the Ml protein. Of all the structural proteins of influenza virus, only NP and Ml showed strong affinity for binding viral RNA or other extraneous RNAs. The 4-kilodalton cyanogen bromide peptide (Gly-129 to Gln-164), exhibited marked affinity for viral RNA, the binding of which was blocked by epitope 2-specific MAb 7E5 but not by MAbs directed to three other epitopes. Viral RNA also bound strongly to the nonodecapeptide SP3 and rather less well to anti-idiotype anti-MAb 7E5; these latter viral RNA-binding reactions were only slightly blocked by preincubation of anti-MAb 7E5 or SP3 with MAb 7E5. These experiments suggest the presence of at least two RNA-binding sites, which also serve as transcription-inhibition sites, centered around amino acid sequences 80 through 109 (epitope 4?) and 129 through 164 (epitope 2) of the 252 amino acid M1 protein of A/WSN/33 influenza virus. A hydropathy plot of the Ml protein calculated by free-energy transfer suggests that the two hydrophilic transcription-inhibition RNA-binding domains are brought into close proximity by an a-helix-forming intervening hydrophobic domain.

Executive summary For almost 60 years, the WHO Global Influenza Surveillance and Response System (GISRS) has been the key player in monitoring the evolution and spread of influenza viruses and recommending the strains to be used in human influenza vaccines. The GISRS has also worked to continually monitor and assess the risk posed by potential pandemic viruses and to guide appropriate public health responses. The expanded and enhanced role of the GISRS following the adoption of the International Health Regulations (2005), recognition of the continuing threat posed by avian H5N1 and the aftermath of the 2009 H1N1 pandemic provide an opportune time to critically review the process by which influenza vaccine viruses are selected. In addition to identifying potential areas for improvement, such a review will also help to promote greater appreciation by the wider influenza and policy‐making community of the complexity of influenza vaccine virus selection. The selection process is highly coordinated and involves continual year‐round integration of virological data and epidemiological information by National Influenza Centres (NICs), thorough antigenic and genetic characterization of viruses by WHO Collaborating Centres (WHOCCs) as part of selecting suitable candidate vaccine viruses, and the preparation of suitable reassortants and corresponding reagents for vaccine standardization by WHO Essential Regulatory Laboratories (ERLs). Ensuring the optimal effectiveness of vaccines has been assisted in recent years by advances in molecular diagnosis and the availability of more extensive genetic sequence data. However, there remain a number of challenging constraints including variations in the assays used, the possibility of complications resulting from non‐antigenic changes, the limited availability of suitable vaccine viruses and the requirement for recommendations to be made up to a year in advance of the peak of influenza season because of production constraints. Effective collaboration and coordination between human and animal influenza networks is increasingly recognized as an essential requirement for the improved integration of data on animal and human viruses, the identification of unusual influenza A viruses infecting human, the evaluation of pandemic risk and the selection of candidate viruses for pandemic vaccines. Training workshops, assessments and donations have led to significant increases in trained laboratory personnel and equipment with resulting expansion in both geographical surveillance coverage and in the capacities of NICs and other laboratories. This has resulted in a significant increase in the volume of information reported to WHO on the spread, intensity and impact of influenza. In addition, initiatives such as the WHO Shipment Fund Project have facilitated the timely sharing of clinical specimens and virus isolates and contributed to a more comprehensive understanding of the glob...

The vaccine-approval process in the United States is regulated by the Center for Biologics Evaluation and Research of the US Food and Drug Administration. Throughout the life cycle of development, from preclinical studies to after licensure, vaccines are subject to rigorous testing and oversight. Manufacturers must adhere to good manufacturing practices and control procedures to ensure the quality of vaccines. As mandated by Title 21 of the Code of Regulations, licensed vaccines must meet stringent criteria for safety, efficacy, and potency.

The ability of baicalin (7-glucuronic acid, 5,6-dihydroxyflavone), a flavonoid compound purified from the Chinese medicinal herb, Scutellaria baicalensis georgi, to inhibit human T cell leukemia virus type I (HTLV-I) was examined. Baicalin produced concentration-dependent inhibition of HTLV-I replication in productively infected T and B cells. Moreover, baicalin treatment selectively reduced the detectable levels of HTLV-I p19 gag protein in infected cells by greater than 70% at concentrations that produced insignificant effects on total cellular protein and DNA synthesis with no loss in cell viability. Resistance to HTLV-I infection and virus-mediated transformation was noted in uninfected peripheral blood lymphocytes pretreated with baicalin before cocultivation with lethally irradiated chronically infected cells. Baicalin inhibited reverse transcriptase activity in HTLV-I-infected cells as well as the activity of purified reverse transcriptase from Moloney murine leukemia virus and Rous-associated virus type 2. These results suggest that baicalin may be a potential therapeutic agent against HTLV-I-associated T cell diseases.