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PubMed2000

A formal model of an artificial immune system.

The paper presents a mathematical model based on the features of antigen-antibody bindings in the immune system. In the natural immune system, local binding of immune cells and molecules to antigenic peptides is based generally on the behavior of surface proteins. In particular, immune cells contain proteins on their receptors, and apparently, these proteins play the key role both in immune response and recognition processes. In this work, we consider the immune cells in the form of formal B-cell and formal T-cell and develop a mathematical model of their interactions. We refer this model as the formal immune system (FIS). The paper provides an analysis of a network of bindings (or interactions) among the formal proteins of the FIS.

Antigen-Antibody Reactions↗
PubMed1996

Vaccination and mucosal responses to Helicobacter pylori infection.

H. pylori infection persists for life if not treated, and is responsible for major morbidity and mortality throughout the world. Preventative immunization, once thought to be impossible, is now considered by many to be the only practical approach to large-scale elimination of the bacterium from susceptible populations. High rates of protection have been achieved in the H. felis mouse model, utilizing antigens ranging from whole cells to purified recombinant proteins selected on the basis of their role in pathogenicity. Immunization has also been shown to cure established infection. H. pylori mouse models have been developed and may become the model of choice. Urease remains the favourite antigen but combinations will most likely be required. A priority is to define alternate muscosal adjuvants, as some used in the animal models may be too toxic for use in humans. Also, there is a need to understand the basis of immunization. Why does the natural immune response to H. pylori fail while the artificially stimulated response succeeds? The first important steps towards a vaccine have been made but, given safety issues and regulatory requirements, it may be 5-8 years before the final product becomes available. Over these years antimicrobial resistance is likely to be an increasing problem in the treatment of H. pylori infections. Thus, when the vaccine comes, the time will be ripe for the completely new approach of therapeutic immunization.

Animals↗
PubMed1977

Influenza A infections in young children. Primary natural infection and protective efficacy of live-vaccine-induced or naturally acquired immunity.

To assess the impact of an influenza A/Port Chalmers infection on normal young children, we monitored 147 children during an epidemic; 121 were seronegative. There was a high attack rate (61 of 147), and a high rate of symptomatic disease (38 of 147), which resulted in frequent physician visits (25 of 38). Influenza accounted for 76 per cent of the sick-child visits during the two-month epidemic period. Young children undergoing primary influenza infection produced hemagglutination inhibition and antineuraminidase antibodies. Because of the immunologic responsiveness of young children, we examined the serologic correlates of protection. Ten children previously infected with influenza A/London and 16 who received live, attenuated A/Hong Kong ts-1[E] vaccine were protected against infection with the non-homologous A/Port Chalmers strain. The morbidity of influenza and ability of the young child to produce protective antibody should encourage evaluation of life, attenuated influenza vaccines in this age group.

Age Factors↗
PubMed1977

The nature of immunity against Babesia hylomysci and B. microti infections in mice.

Mice which have recovered from Babesia microti infection lose their parasitaemia as soon as three weeks after recovery and become solidly immune. This sterile immunity is not affected by splenectomy and may last for the life of the mouse. Mice which have recovered from B. hylomysci infection continue to harbour parasites at a subpatent level and spontaneous relapses were common after recovery. Hence the type of immunity which developed against this parasite is premunition and may last for life. Such immunity was not absolute and considerable parasitaemias developed after challenge. Cross-protection occurred between the two species of parasite.

Animals↗
PubMed2001

Patterns and implications of naturally acquired immune responses to environmental and tuberculous mycobacterial antigens in northern Malawi.

Interferon (IFN)-gamma responsiveness to 12 purified protein derivative (PPD) and new tuberculin antigens from 9 species of mycobacteria was assessed, using a whole blood assay, in 616 young adults living in northern Malawi, where Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccination provides no protection against pulmonary tuberculosis. The prevalence of IFN-gamma responsiveness was highest for PPDs of M. avium, M. intracellulare, and M. scrofulaceum (the MAIS complex). Correlations between responsiveness paralleled genetic relatedness of the mycobacterial species. A randomized, controlled trial was carried out, to assess the increase in IFN-gamma responsiveness to M. tuberculosis PPD that can be attributed to M. bovis BCG vaccination. The BCG-attributable increase in IFN-gamma response to M. tuberculosis PPD was greater for individuals with low initial responsiveness to MAIS antigens than for those with high initial responsiveness. Although not statistically significant, the trend is consistent with the hypothesis that prior exposure to environmental mycobacteria interferes with immune responses to BCG vaccination.

Antigens, Bacterial↗
PubMedDate not supplied

Vaccines for the prevention of human cytomegalovirus infection.

The status of vaccination against cytomegalovirus (CMV) at the end of 1988 was as follows: (1) The Towne live attenuated vaccine produces humoral and cellular immune responses without viral excretion or demonstrated latency. (2) The Towne vaccine partially protects seronegative renal transplant recipients from severe CMV disease but does not prevent them from getting infected. (3) In healthy subjects the live vaccine is also protective, but protection is related to challenge dose. Vaccine-derived immunity is equivalent to natural immunity for prevention of disease but at higher challenge doses is less protective for prevention of infection. (4) The viral envelope contains proteins that can stimulate humoral and cellular immune responses, although it is not yet clear whether the responses are as protective as those following infection. (5) One glycoprotein of the envelope, the 55-58K protein, can stimulate the same responses. If large amounts of this protein can be produced by molecular biologic techniques, this protein might be used as a subunit vaccine. (6) Target groups for vaccination would include seronegative healthy women and seronegative or seropositive recipients of solid organ transplants.

Antibodies, Viral↗
PubMedDate not supplied

Antisperm immunity in natural and assisted reproduction.

Research conducted in the last 40 years has provided evidence that antisperm antibodies (ASA) can impair the fertilizing capacity of human spermatozoa. It is established that ASA can be present at different sites, can act against different antigens and can impair fertility in various ways. In fact, in the past it was amply demonstrated that ASA can act negatively on sperm motility and on cervical mucus penetration. In recent years, owing to the improvement and spreading of IVF techniques, it has been possible to demonstrate the effect of antibody-bound spermatozoa at the level of in-vitro gamete interaction. The literature demonstrates that the various previously used treatments for immunological infertility, i.e. medical therapy, intrauterine insemination with husband's spermatozoa (AIH) and IVF, usually had poor success. The primary choice of treatment in immunological infertility, especially in the most severe cases and when the sperm head is involved, is ICSI. ASA evaluation in all couples who undergo the various techniques of insemination or IVF is imperative.

Animals↗