Comparison of the novel ResPlex III assay and existing techniques for the detection and subtyping of influenza virus during the influenza season 2006-2007.

Influenza virus is a major cause of disease worldwide. The accurate detection and further subtyping of influenza A viruses are important for epidemiologic surveillance, and subsequent comprehensive characterization of circulating influenza viruses is essential for the selection of an optimal vaccine composition. ResPlex III is a new multiplex reverse transcriptase polymerase chain reaction (RT-PCR)-based method for detecting, typing, and subtyping influenza virus in clinical specimens. The ResPlex III assay was compared with other methods with respect to sensitivity and accuracy, using 450 clinical specimens obtained from subjects throughout Germany during the 2006-2007 influenza season. Samples were analyzed for the presence of influenza virus in Madin-Darby canine kidney (MDCK) cells by rapid cell culture using peroxidase staining and conventional cell culture confirmed by hemagglutination inhibition assay, a rapid diagnostic assay (Directigen Flu A+B test; BD Diagnostic Systems, Heidelberg, Germany), in-house real-time RT-PCR (RRT-PCR), and ResPlex III (Qiagen, Hilden, Germany). ResPlex III had the highest sensitivity for detecting influenza virus in clinical specimens, followed by in-house RRT-PCR (96% compared with ResPlex III). Conventional cell culture in MDCK cells, rapid culture, and quick test assays were substantially less sensitive (55%, 72%, and 39%, respectively). Virus subtyping results were identical using ResPlex III and the standard virological subtyping method, hemagglutination inhibition. ResPlex III is a quick, accurate, and sensitive assay for detecting and typing influenza A and B viruses and subtyping influenza A viruses in clinical specimens, and might be considered for a supplemental role in worldwide seasonal and pandemic influenza surveillance.

DNA vaccines.

Immunization by genes encoding immunogens, rather than with the immunogen itself, has opened up new possibilities for vaccine research and development and offers chances for new applications and indications for future vaccines. The underlying mechanisms of antigen processing, immune presentation and regulation of immune responses raise high expectations for new and more effective prophylactic or therapeutic vaccines, particularly for vaccines against chronic or persistent infectious diseases and tumors. Our current knowledge and experience of DNA vaccination is summarized and critically reviewed with particular attention to basic immunological mechanisms, the construction of plasmids, screening for protective immunogens to be encoded by these plasmids, modes of application, pharmacokinetics, safety and immunotoxicological aspects. DNA vaccines have the potential to accelerate the research phase of new vaccines and to improve the chances of success, since finding new immunogens with the desired properties is at least technically less demanding than for conventional vaccines. However, on the way to innovative vaccine products, several hurdles have to be overcome. The efficacy of DNA vaccines in humans appears to be much less than indicated by early studies in mice. Open questions remain concerning the persistence and distribution of inoculated plasmid DNA in vivo, its potential to express antigens inappropriately, or the potentially deleterious ability to insert genes into the host cell's genome. Furthermore, the possibility of inducing immunotolerance or autoimmune diseases also needs to be investigated more thoroughly, in order to arrive at a well-founded consensus, which justifies the widespread application of DNA vaccines in a healthy population.

Immune response of chimpanzees after immunization with the inactivated whole immunodeficiency virus (HIV-1), three different adjuvants and challenge.

Purified whole virus preparations of HIV-1 were produced from supernatants of infected cells and concentrated 5000-fold. After inactivation with formaldehyde, the concentrates were combined with one of three different adjuvants, and used to immunize three groups of three chimpanzees each. The chimpanzees were monitored for HIV-specific humoral and cellular immune responses by ELISA, immunoblot, virus neutralization, delayed-type hypersensitivity, lymphocyte proliferation and antibody-dependent cell-mediated cytotoxicity. Weak and inconsistent responses were observed in animals that received HIV-1 formulated with alum as adjuvant, whereas HIV-1 formulated with incomplete Freund's adjuvant or an experimental adjuvant (BWZL) induced good humoral and cellular immune responses to the virus. The three animals that received HIV-1 with the BWZL adjuvant generated overall the best immune responses; therefore, 2 weeks after the sixth immunization these animals were challenged with infectious HIV-1. Despite the presence of good humoral and cell-mediated immunity, all three immunized animals and a control animal became infected within 4 weeks, as evidenced by repeated isolation of HIV-1 from peripheral blood mononuclear cells and anamnestic antibody responses. The new experimental adjuvant has to be further investigated in other vaccine trials and different animal models.

Virus safety of human immunoglobulins: efficient inactivation of hepatitis C and other human pathogenic viruses by the manufacturing procedure.

Human immunoglobulins are plasma derivatives with a low risk of transmitting viral infections. To the present, no proven case of human immunoglobulins transmitting human immunodeficiency viruses has been reported. However, there have been a few reports on the transmission of hepatitis C virus by these plasma proteins. To improve further the safety of both 5s iv human immunoglobulins and 7s im immunoglobulins, we introduced a 10-hour heat treatment of the aqueous solutions at 60 degrees C (i.e., pasteurization) into the manufacturing procedure. This treatment was not added to the manufacturing procedure of 7s iv immunoglobulin that already contained the S-sulfonation as a virus inactivating method. We now report on experimental data that show that the whole manufacturing procedures of the above immunoglobulins inactivate efficiently hepatitis C virus and that the specific virus inactivation methods alone, namely, pasteurization or S-sulfonation, also inactivate completely viruses of the flavivirus family, to which the hepatitis C virus belongs. The inactivation of the Flaviviridae bovine viral diarrhea virus, tick-borne encephalitis virus, and yellow fever virus by pasteurization or S-sulfonation was at least 10(5). The clearance of HCV achieved by the entire manufacturing process of each of these immunoglobulins was also at least 10(5). The experiments therefore show that pasteurization or S-sulfonation provides a high margin of safety to human immunoglobulins regarding the transmission of hepatitis C virus.

Inactivation of retroviruses in biologicals manufactured for human use.

Human immunodeficiency virus may occur in human plasma and mammalian retroviruses in established cell lines used for the production of monoclonal antibodies or recombinant proteins. To avoid any risk of retrovirus infections being transmitted to human patients by human plasma proteins or other biologicals obtained from established cell lines, these products must be free of contaminating retroviruses. This can be achieved by excluding contaminated source material and by establishing manufacturing procedures which inactivate and eliminate retroviruses. Some methods were investigated, and it was proved that these methods not only completely inactivate retroviruses, but that they are at the same time mild enough not to destroy the biological activities of the substances to be used as therapeutics. In addition, the clearance of retroviruses by the entire manufacturing process of an immunoglobulin, human plasminogen, a murine monoclonal antibody and a recombinant human protein were studied. In each case cumulative clearance factors of greater than 10(12) were achieved for the retroviruses used in these spiking experiments. It can be concluded that these high clearance factors contribute a very high margin of safety to the biologicals manufactured.

Expression and characterization of human CD4:immunoglobulin fusion proteins.

Different chimeric antibody-like molecules consisting of the four human CD4 extracellular domains (amino acids 1-369) fused to different parts of human IgG1 and IgM heavy-chain constant regions have been created and expressed in mammalian cells. For both IgG1 and IgM fusion proteins, the best expression in COS cells was observed for molecules lacking the CH1 domain of the heavy-chain constant region. The chimeric molecules are potent inhibitors of human immunodeficiency virus (HIV) infection and HIV-mediated cytotoxicity. A CD4:IgG1 hinge fusion protein, which was analyzed in more detail, binds efficiently to HIV gp160 and human Fc receptors and shows complement-assisted inhibition of viral propagation in culture. Half-life studies after intravenous application of the latter human fusion protein into mice and monkeys showed significant prolongation of serum survival compared to soluble CD4. An IgG2b murine homolog of the human CD4:IgG1 hinge fusion protein was prepared and evaluated in mice, where it was found to be nontoxic and to have no detectable effect on the humoral response to soluble antigen.

Antibody- and complement-mediated lysis of HIV-infected cells and inhibition of viral replication.

HIV-1-positive antisera were tested for their ability to lyse HIV-1-infected cells in the presence of active complement. Cytolytic effects caused by sera derived from infected humans were slower than those observed with sera from immunised chimpanzees. Lytic but also negative sera were found among HIV-1-infected asymptomatic men as well as among clinical AIDS cases. Human antisera that lysed infected cells reacted similarly irrespective of whether the complement was heterologous or autologous. Analysis of complement-mediated lysis using defined antisera against recombinant HIV-1 env or core antigens suggested that gp160/gp120 and p24 can act as target antigens for an antibody- and complement-mediated cytolysis of infected cells. Complement alone reduced the spread of HIV-1 infection in CD4+ cells and the ability of HIV-1 and HIV-2 to form plaques in CD4-transfected HeLa cells. Co-operative effects of specific antibodies and complement were the most effective in inhibiting HIV infections.

Inactivation of HIV-1 and HIV-2 by various manufacturing procedures for human plasma proteins.

Human retroviruses causing AIDS (HIV-1, HIV-2) can occur in human plasma donations. Since HIV-contaminated plasma cannot be completely excluded by testing for anti-HIV-1 (routine plasma screening for anti-HIV-2 has not yet been established), a safeguard against AIDS in therapeutics derived from human plasma can only be achieved by introducing HIV inactivating/eliminating methods into the manufacturing process of plasma derivatives. To investigate the HIV inactivating efficiency of such methods, aliquots of infectious HIV-1 or HIV-2 concentrates were added to a protein preparation, the resulting HIV spiked preparation was then treated according to the method to be studied, and the amount of infectious HIV in this preparation was determined before and after treatment. Methods by which HIV-1 or HIV-2, respectively, were completely inactivated were ethanol fractionation according to the Cohn procedure, pepsin treatment, affinity chromatography, protein precipitation by various methods, and pasteurization (heat treatment at 60 degrees C in aqueous solution). The use of these methods for manufacturing human plasma derivatives resulted in products that were free of any infectious HIV-1 or HIV-2 and thus unable to transmit AIDS.

A CD 4: immunoglobulin fusion protein with antiviral effects against HIV.

Antibody-like molecules consisting of the human CD 4 extracellular domain fused to human IgG1 heavy chain constant regions were genetically constructed and expressed in a BHK cell stable transfectant. Purified chimeric antibodies bound to HIV particles as it was shown by immuno electron microscopy, inhibited fusions of HIV-1-infected cells with uninfected cells, neutralized HIV-1, and were able to inhibit the spread of a cellular HIV-1 infection in CD 4+ cells. Plaque reduction assays with CD 4(+)-transfected Hela-cells showed a comparable inhibition of HIV-1 and HIV-2. Inhibitory functions were enhanced in the presence of complement. HIV-1- and HIV-2-infected CD 4+ cells were efficiently lysed by a slow, complement-dependent mechanism, whereas uninfected CD 4+ cells and HLA-DR+ cells were not affected.

Inactivation of AIDS-causing retroviruses by the manufacturing procedures for human plasma proteins.

Human retroviruses causing AIDS (HIV) may occur in human plasma. Since HIV contaminated plasma cannot be completely excluded by testing for anti-HIV, AIDS safety of human plasma products can only be achieved by introducing HIV inactivating and/or eliminating methods into the manufacturing procedure. Here we review a number of methods used when manufacturing plasma derivatives at Behringwerke. These methods were previously developed either to produce a protein of required purity or to manufacture hepatitis safe products. Methods used to produce purer proteins are ethanol fractionation, pepsin treatment, affinity chromatography or various protein precipitation procedures. The method developed at Behringwerke for inactivating infectious viruses in plasma protein preparations not destroying the biological activities of the human protein is pasteurization, i.e. 10 h heat treatment of the aqueous protein solution at 60 degrees C. To investigate the HIV inactivating efficiency of the methods mentioned above, aliquots of an infectious HIV type 1 concentrate were added to a protein preparation, the resulting HIV spiked preparation treated according to the method to be studied and the amount of infectious HIV in this preparation determined before and after treatment. By all methods reported on here the HIV type 1 isolate was completely inactivated resulting in high inactivation factors. In addition, the heat stability of HIV type 2 was tested in aqueous solution at 60 degrees C proving that both HIV-1 and HIV-2 isolates are of comparably low heat stability under these conditions. From the results discussed here it can be concluded that all commercial human protein products of Behringwerke derived from either human plasma or placenta do not contain any infectious retrovirus causing AIDS and thus have a high margin of safety regarding the transmission of AIDS.

Detection of human immunodeficiency virus and other retroviruses in cell culture supernatants by a reverse transcriptase microassay.

A micromethod for the detection of human immunodeficiency virus (HIV) and other retroviruses in cell culture supernatants is described which applies a DEAE ion exchanger for recovery of polynucleotides synthesized in vitro by the retroviral reverse transcriptase. Cell culture, sample preparation, and test performance including the washing step are adapted to microtitre plates. Compared to the standard method this technique produced less non-specific reactions, resulting in a more than 3-fold higher sensitivity, a higher reproducibility due to lower intrarun variations and allowed an increase in the daily sample accomplishment per person 3- to 4-fold at lower costs per sample.

Adaptation of hepatitis A virus to high titre growth in diploid and permanent cell cultures.

A hepatitis A virus isolate originally obtained from the feces of a clinically ill patient and passaged in diploid human embryonic kidney and lung cells was adapted to grow in MRC-5, Cercopithecus aethiops muscle and in Vero cells. Three different adaptation methods were applied. Either method proved to be suitable to finally give high virus titres of cell-bound as well as cell-free virus in the supernatant of infected cultures during 10 to 15 passages. An easily performable immunoperoxidase staining method was used for the titration of hepatitis A virus in microtitre plates. Cytopathogenic changes in MRC-5 cell cultures infected with fully adapted virus are described.

Bovine herpesvirus 1: differentiation of IBR- and IPV-viruses and identification and functional role of their major immunogenic components.

Infectious Bovine Rhinotracheitis (IBR) and Infectious Pustular Vulvovaginitis (IPV) virus strains of Bovine Herpesvirus 1 (BHV-1) can be differentiated by restriction endonuclease digestion of their DNAs. Antigens and polypeptide patterns of isolates of these different clinical entities are almost identical. Page analysis of immunoprecipitates revealed three major immunogenic components in BHV-1 infected cells. These are glycoproteins with apparent molecular weights of 93,000 (GP93), 74,000 (GP74) and 69,000 daltons (GP69), respectively. Bovine convalescent sera and antisera, which are directed against individual precipitates derived from crossed immunoelectrophoresis, contain antibodies reacting with one or more of these glycoproteins. The experiments with these antisera demonstrate that GP74 and possibly GP93, both structural components of the BHV-1 virion, induce neutralizing antibodies, whereas GP69, a non-structural protein, does not.

Plaque/focus immunoassay: a simple method for detecting antiviral monoclonal or other antibodies and viral antigens in cells.

A new, simple enzyme-linked immunosorbent assay (ELISA) is described which is performed directly on infected and fixed cell cultures in microtitre plates. It permits large scale screening of antiviral monoclonal antibodies and differentiation of specific antibodies from those usually responsible for high background reactions in other ELISA techniques. Time consuming purification of antigens is thus avoided. The plaque/focus immunoassay is also applicable to titration of antibodies in patients' sera and antigens in lytically or non-lytically virus-infected cells. It may also be used to localize antigens in different cell compartments. This immunoassay requires no special equipment and results may be evaluated either with the naked eye or using a light microscope.