The cost of an immune response: vaccination reduces parental effort

A fundamental assumption of theories of the ecology and evolution of inducible defences is that protective responses to attacks by parasites or predators should not only have benefits, but also costs. The vertebrate immune system is by far the best studied example of an inducible defence, yet little is known about the costs of an immune response, especially in natural populations. To test if an immune response per se is costly, we induced an antibody response in female blue tits, Parus caeruleus , by immunising them with human diphtheria–tetanus vaccine, and compared their nestling-feeding rate with that of saline-injected controls. We found that vaccinated females reduced their nestling feeding rate, thus demonstrating a cost of the immune response in the currency of parental effort.     

The immune response to Giardia

The flagellate Giardia duodenalis has been considered for many years to be a commensal living in the lumen of the small intestine of its host. It is only 25 years ago that it was accepted that Giardia is a significant pathogen of humans. Knowledge that Giardia can elicit an immune response that would probably contribute to the onset or absence of symptoms is not much older. The use of animal models to study the disease in the laboratory, together with the production of the whole life cycle in a test tube, have contributed greatly to our present knowledge of the immune responses to Giardia and of antigens that are specific to the trophozoite or cyst stages. In this review, Gaétan Faubert focuses on studies published since the last review in Parasitology Today in 1988, and examines the roles played by the humoral and cell-mediated immune responses in the control of the infection. It also covers the immunodiagnostic assays that have been recently developed on the basis of advances in our knowledge of the antigens of Giardia.     

Engineering custom-designed osteochondral tissue grafts

Tissue engineering is expected to help us outlive the failure of our organs by enabling the creation of tissue substitutes capable of fully restoring the original tissue function. Degenerative joint disease, which affects one-fifth of the US population and is the country's leading cause of disability, drives current research of actively growing, functional tissue grafts for joint repair. Toward this goal, living cells are used in conjunction with biomaterial scaffolds (serving as instructive templates for tissue development) and bioreactors (providing environmental control and molecular and physical regulatory signals). In this review, we discuss the requirements for engineering customized, anatomically-shaped, stratified grafts for joint repair and the challenges of designing these grafts to provide immediate functionality (load bearing, structural support) and long-term regeneration (maturation, integration, remodeling).     

The local specific immune response to Staphylococcus aureus protein A in human tonsillar lymphoid tissue

Formation of antibodies and development of delayed hypersensitivity to protein A are usual components of the immune response of tonsillar lymphoid tissue to S. aureus infection in chronic tonsillitis in man. The preparations of transfer factor, produced from human tonsillar T-cells, show increased activity in the intraspecific transfer of delayed hypersensitivity to staphylococcal protein A from humans to mice.     

The coral immune response facilitates protection against microbes during tissue regeneration

Increasing physical damage on coral reefs from predation, storms and anthropogenic disturbances highlights the need to understand the impact of injury on the coral immune system. In this study, we examined the regulation of the coral immune response over 10 days following physical trauma artificially inflicted on in situ colonies of the coral Acropora aspera, simultaneously with bacterial colonization of the lesions. Corals responded to injury by increasing the expression of immune system‐related genes involved in the Toll‐like and NOD‐like receptor signalling pathways and the lectin–complement system in three phases (<2, 4 and 10 days post‐injury). Phenoloxidase activity was also significantly upregulated in two phases (<3 and 10 days post‐injury), as were levels of non‐fluorescent chromoprotein. In addition, green fluorescent protein expression was upregulated in response to injury from 4 days post‐injury, while cyan fluorescent protein expression was reduced. No shifts in the composition of coral‐associated bacterial communities were evident following injury based on 16S rRNA gene amplicon pyrosequencing. Bacteria‐specific fluorescence in situ hybridization also showed no evidence of bacterial colonization of the wound or regenerating tissues. Coral tissues showed near‐complete regeneration of lesions within 10 days. This study demonstrates that corals exhibit immune responses that support rapid recovery following physical injury, maintain coral microbial homeostasis and prevent bacterial infestation that may compromise coral fitness.     

Fish immune response to Myxozoan parasites

Myxozoan parasites are responsible for important economic losses among fisheries and aquaculture industries, and hence the high interest in studying the immune response of fish against them. The most important data available concerning the immune response of fish against myxosporeans are reviewed, with emphasis on the different innate and adaptive immune mechanisms, their relationship with natural and acquired resistance and the strategies to control and prevent myxosporoses. Cellular effectors (lymphocytes, granulocytes, phagocytes, non-specific cytotoxic cells, rodlet cells) and humoral factors (lysozyme, peroxidades, antiproteases, complement, specific antibodies) have been examined for several myxosporoses, and some immune relevant genes have been studied. This information will be crucial for the future development of vaccines and other preventive strategies such as immunomodulation and selection of disease-resistant strains     

The immune response to Epstein-Barr virus

Epstein-Barr virus is a gammaherpes virus that establishes persistent infection in the majority of humans. Despite the potent oncogenic potential of the virus it is relatively rarely associated with malignant disease. This review focuses on the cellular immune responses that successfully control Epstein-Barr virus infection in most individuals.     

Innate immune response to viral infection

In viral infections the host innate immune system is meant to act as a first line defense to prevent viral invasion or replication before more specific protection by the adaptive immune system is generated. In the innate immune response, pattern recognition receptors (PRRs) are engaged to detect specific viral components such as viral RNA or DNA or viral intermediate products and to induce type I interferons (IFNs) and other pro-inflammatory cytokines in the infected cells and other immune cells. Recently these innate immune receptors and their unique downstream pathways have been identified. Here, we summarize their roles in the innate immune response to virus infection, discrimination between self and viral nucleic acids and inhibition by virulent factors and provide some recent advances in the coordination between innate and adaptive immune activation.     

Mouse immune response to meningococcal antigens

The mouse immune response against Neisseria meningitidis was studied by using an extract from group Y (Slaterus) known to contain protein antigens common to other meningococci. By using a solid-phase radioimmunoassay, high titers of specific IgM and IgG class antibodies were measured which lasted over 2 months after immunization. These antibodies cross-reacted with similar extracts from other meningococci groups. Bactericidal antibodies directed against protein antigens were also elicited after immunization and they belonged to IgM, IgG2a, and IgG2b isotypes. Cellular immunity, expressed as delayed type hypersensitivity under the conditions tested, could be detected neither in homologous nor heterologous reactions.     

Accelerated immune response to DNA vaccines

DNA vaccines offer considerable promise for improvement over conventional vaccines. For the crucial step of delivering DNA vaccines intracellularly, electroporation (EP) has proven to be highly effective. This method has yielded powerful humoral and cellular responses in various species, including nonhuman primates. In an attempt to further improve DNA vaccination we used micron-size gold particles (which do not bind or adsorb DNA) as a particulate adjuvant which was coinjected with DNA intramuscularly into mice, followed by EP of the target site. The presence of gold particles accelerated the antibody response significantly. Maximum titers against hepatitis B surface antigen (HBsAg) were reached after one boost in 6 weeks, whereas 8 weeks were required without particles. These immunizations were effective in protecting mice against tumor challenge with cancer cells expressing HBsAg as a surrogate cancer antigen. Computer modeling of electric fields and gene expression studies indicate that gold particles do not stimulate EP and subsequent antigen expression. The particles may act as an attractant for immune cells, especially antigen presenting cells. We conclude that particulate adjuvants combined with DNA vaccine delivery by EP reduces the immune response time and may increase vaccine efficacy. This method may become valuable for developing prophylactic as well as therapeutic vaccines. The rapid response may be of particular interest in countering bio-terrorism.     

Different sensitivities to hydrocortisone of natural killer cell activity and hybrid resistance to parental marrow grafts.

Natural killer cells and cells mediating F1 anti-parent responses in vivo and in vitro differ in their sensitivity to hydrocortisone acetate. NK cell activity is sharply decreased after in vivo drug administration whereas induction of specific F1 anti-parent or anti-allogeneic cytotoxicity and hybrid resistance to parental marrow grafts are not impaired. Because of several other properties shared by the NK and anti-Hh host reactivities, it is still suggested that the effector cells are generated from a single differentiation pathway, but that they differ with respect to specificity and sensitivity to hydrocortisone.