Interactions of antibodies, complement components and various cell types in immunity against viruses and pyogenic bacteria

Vaccination against the M protein of Streptococcus pyogenes prevents death after influenza virus: S. pyogenes super-infection

Influenza virus infections are associated with a significant number of illnesses and deaths on an annual basis. Many of the deaths are due to complications from secondary bacterial invaders, including Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pyogenes. The β-hemolytic bacteria S. pyogenes colonizes both skin and respiratory surfaces, and frequently presents clinically as strep throat or impetigo. However, when these bacteria gain access to normally sterile sites, they can cause deadly diseases including sepsis, necrotizing fasciitis, and pneumonia. We previously developed a model of influenza virus:S. pyogenes super-infection, which we used to demonstrate that vaccination against influenza virus can limit deaths associated with a secondary bacterial infection, but this protection was not complete. In the current study, we evaluated the efficacy of a vaccine that targets the M protein of S. pyogenes to determine whether immunity toward the bacteria alone would allow the host to survive an influenza virus:S. pyogenes super-infection. Our data demonstrate that vaccination against the M protein induces IgG antibodies, in particular those of the IgG1 and IgG2a isotypes, and that these antibodies can interact with macrophages. Ultimately, this vaccine-induced immunity eliminated death within our influenza virus:S. pyogenes super-infection model, despite the fact that all M protein-vaccinated mice showed signs of illness following influenza virus inoculation. These findings identify immunity against bacteria as an important component of protection against influenza virus:bacteria super-infection.

Recombinant human Fab to glycoprotein D neutralizes infectivity and prevents cell-to-cell transmission of herpes simplex viruses 1 and 2 in vitro

Herpes simplex viruses 1 and 2 (HSV-1 and -2) are associated with a number of conditions of varying severity, which are only partially responsive to current therapies. Human antibodies to the viruses offer a potential alternative. We describe here the generation of panels of human monoclonal Fab fragments to HSV-1 and -2 by panning a phage display combinatorial antibody library against whole lysates from the two viruses. Each lysate selected a largely distinct set of Fabs, although all of the Fabs were cross-reactive with both viruses. In a plaque-reduction assay, one Fab neutralized HSV-1 at 0.25 microgram/ml (50% reduction) and HSV-2 at 0.05 microgram/ml. This Fab also inhibited plaque formation when applied to virus-infected monolayers, completely abolishing HSV-2 plaque development at 25 micrograms/ml 72 hr postinfection, indicating the ability of the Fab to prevent cell-to-cell spread of virus. The Fab was shown to recognize viral glycoprotein D and to neutralize virus primarily by a postattachment mechanism. Recombinant Fabs may be useful for topical administration, although whole antibody will probably be required for systemic use.

Immunological elimination of infected cells as the candidate mechanism for tumor protection in polyomavirus-infected mice

The uniformly lethal development of mammary tumors in polyomavirus-infected adult female nude mice was prevented by adoptive cell transfer of polyomavirus-immune splenocytes or peritoneal cells. Transferred immune cells also lowered the growth rate of emerging tumors. The induction of other relatively less frequent tumors of the skin and bone was decreased as well. Using in situ hybridization of whole-body sections as well as hybridization of nucleic acids from the mammary glands, we show for the first time that transferred immune cells, but not normal cells, virtually eliminated virus signal in the whole mouse and in the mammary glands. Since infected and tumorous mammary glands produce very little infectious virus, it appears that a major mechanism mediating the prevention of polyomavirus oncogenesis involves the immunological elimination of nonproductively and persistently infected cells.

Cloning of human T cells specific for measles virus haemagglutinin and nucleocapsid

T cell lines specific for measles virus (MV) were generated from blood of two DR1/DR2 heterozygous healthy donors with a history of past measles infection. The antigenic specificity of 66 T cell clones derived from the lines was studied in a blastogenic assay using whole measles virus and two purified virus components, haemagglutinin and nucleocapsid. Thirty-nine of the clones were specific for one of the two purified antigens. None of the seven synthetic peptides covering 20% of the MV haemagglutinin amino acid sequence stimulated T cell clones with haemagglutinin specificity. Responsiveness of the majority of the clones were restricted by HLA-D/DR antigens, although two clones were isolated that responded only to MV antigens presented by autologous cells. Ten of 11 clones recognizing the nucleocapsid antigen were DR1-restricted, while the haemagglutinin antigen and whole measles virions were recognized more often in association with the DR2 antigen. These results indicate that much of the MV-specific memory T cell response is specific for the haemagglutinin and nucleocapsid virus antigens, with the DR antigen being the main restriction element involved.

The primary site of replication alters the eventual site of persistent infection by polyomavirus in mice

Using DNA blot analysis, we monitored the course of polyomavirus infection in mice receiving an intranasal inoculation and compared this with the course of infection in mice receiving an intraperitoneal inoculation. Intranasal infection was characterized by an initial primary replication phase in the respiratory tract, followed by a systemic infection of the visceral organs. At 12 days postinfection, there was partial clearing of viral DNA in all organs; by 22 days postinfection, viral DNA persisted only in the lungs and kidneys, and the level of DNA slowly decreased during the next 3 months. Lungs have been a previously unrecognized site for polyomavirus persistent infection. In contrast to intranasal infection, intraperitoneal infection of mice was characterized by only three phases: an initial systemic phase in which viral DNA was found in the same respiratory and visceral organs as during intranasal infection, clearing of the virus from the organs, and ultimately, a persistent infection in the kidneys but not in the lungs. Thus, different organs became persistently infected when mice were inoculated via these different routes.

Recovery of mice from herpes simplex virus type 2 hepatitis: adoptive transfer of recovery with immune spleen cells

Young BALB/c mice inoculated intraperitoneally with herpes simplex virus type 2 develop focal necrotizing hepatitis. After infection, the livers of these mice show increasing virus titers, which reach a maximum on day 3 after infection; this is followed by a dramatic decrease in the amount of virus recovered on days 4 and 5. This decrease in virus content is accompanied by a progressive infiltration of the lesions with mononuclear leukocytes and an apparent resolution of the lesions. Adoptive transfer of immune spleen cells from mice infected 6 days earlier accelerated this process. When 50 x 10(6) to 100 x 10(6) immune spleen cells were transferred 24 h after infection, the inflammatory response and the clearance of virus from the livers were advanced by almost 2 days. As few as 12 x 10(6) immune spleen cells accelerated the healing process, whereas fewer immune cells, disrupted immune cells, or normal spleen cells did not have an effect. The protection conferred by herpes simplex virus type 2-sensitized immune spleen cells was specific since mouse cytomegalovirus- or vaccinia virus-sensitized immune spleen cells had no effect on the course of infection with herpes simplex virus type 2, whereas some cross-reactivity was observed between herpes simplex virus types 1 and 2. This model seems to be suitable for examining the immunological mechanisms that are active during recovery from visceral herpes simplex virus infections.

Antibody-mediated destruction of virus-infected cells

This chapter describes the effect of antibody on virus-infected cells with special reference to the human system. The destruction by antibody of the infected cells through the mediation of complement is described in detail based in considerable part on the contributions of the authors. Activation of the alternative pathway by the various infected cells is of special interest. The interesting effect of the antibody-dependent cell-mediated cytotoxicity (ADCC) system involving viral antigens in cell killing is also presented. Multiple additional topics are also covered, such as the effect of antibody on the expression of viral proteins both on the surface of the cell and intracellularly. Serum antibody, produced in response to virus infections, is of major importance in preventing the spread of infection by virtue of neutralizing free virus in extracellular fluids. Virus neutralization by antibody is enhanced by complement. Antibody binding to the surface of virus-infected cells can affect virus production and release in the absence of an effector system. Immunoglobulin (IgG) antibody can mediate the destruction of virus-infected cells in conjunction with complement or cytotoxic lymphocytes. In addition, at a conceptual level there is evidence to suggest that antibody may enhance and confer specificity on basic nonspecific humoral and cell-mediated defense mechanisms.

Cell-mediated immunity against herpes simplex induction of cytotoxic T lymphocytes

The conditions required for the induction of both primary cytotoxic T lymphocytes (CTL) in vivo and secondary CTL in vitro against herpes simplex virus type 1 (HSV-1)-infected cells were defined. Primary CTL responses occurred only in mice exposed to infectious HSV-1. These responses, which were shown to be mediated by T lymphocytes, peaked at 1 week and had disappeared by 2 weeks after infection. The level of primary cytotoxicity was enhanced by treatment of mice with cyclophosphamide before infection. Secondary in vitro CTL responses were more pronounced and were induced by some forms of inactivated virus as well as by infectious HSV-1. Thus, both ultraviolet light- and glutaraldehyde-inactivated preparations of HSV-1 induced CTL, but heat-inactivated and detergent-extracted antigens failed to do so. The reasons for the differing efficiency of infectious and noninfectious HSV-1 for induction of CTL are discussed.

Generation of virus-specific cytolytic activity in human peripheral lymphocytes after vaccination with vaccinia virus and measles virus

Human peripheral blood lymphocytes (PBL) harvested after vaccination with vaccinia or measles virus showed a specific activity against virus-infected target cells. This activity peaked on day 7 and was specific for the target cells infected with the virus used for the vaccination. The cytotoxic activity was not related to HLA markers. The cells involved in the cytolytic process were lymphocytes bearing Fc receptors. In addition, the cytotoxic activity was abrogated by more than 90% by rabbit Fab'2 anti-human IgG. It is therefore likely that two subpopulations of lymphocytes are involved: an antibody-secreting cell providing specific antiviral antibody and an effector cell bearing Fc receptor (K cells). Finally, these experiments suggest that antibody-dependent cell cytotoxicity may play a major role in the recovery from virus infection in man.

Comparison of the antiviral effects of 5-methoxymethyl-deoxyuridine with 5-iododeoxyuridine, cytosine arabinoside, and adenine arabinoside

The antiviral activity of 5-methoxymethyl-2'-deoxyuridine (MMUdR) was compared with that of 5-iodo-2'-deoxyuridine (IUdR), cytosine arabinoside (Ara-C), and adenine arabinoside (Ara-A). At concentrations of 2 to 4 mug/ml, MMUdR was inhibitory to herpes simplex virus type 1, but concentrations as high as 128 mug/ml were not inhibitory to three other herpesviruses tested (equine rhinopneumonitis virus, murine cytomegalovirus, and feline rhinopneumonitis virus) or to vaccinia virus. The other nucleosides, in contrast, were inhibitory at similar concentrations (1 to 8 mug/ml) against all viruses tested. The inhibition of HSV-1 by MMUdR appeared to be the result of interference with virus replication rather than the result of drug toxicity to host cells. The drug was not toxic to host cells at 100 times the antiviral concentrations, and pretreatment of host cells with high concentrations of MMUdR had no effect on subsequent virus replication. Combination of MMUdR with either IUdR, Ara-A, or Ara-C gave an enhanced antiviral effect, suggesting that the mechanism of action of MMUdR is different from that of the other three drugs. Antiviral indexes were calculated for each compound and were found to be >250, 80, 40, and 8 for MMUdR, IUdR, Ara-A, and Ara-C, respectively. These were defined as the minimum dose at which toxicity was observed microscopically divided by the dose which reduced plaque numbers by 50%.