Hepatitis C virus expressing flag-tagged envelope protein 2 has unaltered infectivity and density, is specifically neutralized by flag antibodies and can be purified by affinity chromatography

Hepatitis C virus (HCV) purification by ultracentrifugation is difficult because of the low and heterogeneous density of native and cultured viruses. It was recently shown that inserting flag tag into envelope protein 2 (E2) of HCV permitted virus purification by affinity chromatography. However, flag-tagged viruses had drastically altered properties, and purification yield was low. In this study, we found that insertion of flag tag at the N-terminus of E2 in HCV recombinant J6/JFH1 did not affect viability in Huh7.5 cells, and that flag-tagged virus had physiochemical properties similar to the original virus. Flag-tagged virus was susceptible to flag-specific antibody neutralization, and infected cells could be immuno-stained by anti-flag antibodies. Using affinity chromatography with anti-flag resin we repeatedly obtained ~ 30% recovery of infectious particles. The full viability and unaltered physiochemical properties of flag-tagged HCV is an important improvement for utilizing these viruses for imaging, virion composition analysis and possibly vaccine development.     

The structural basis of antigenic determinants on V kappa 21 light chains

Antisera were raised against L chains of the V_κ21 group. These antisera divide the six structurally defined subgroups of V_κ21 into two serogroups. The residues thought to comprise the Serogroup I and Serogroup II determinants were located by comparing the complete V region sequences in Serogroup I(16 proteins) and Serogroup II (8 proteins) to each other and to non-V_κ21 chains. The positions implicated in the V_κ21 serogroup specificities were position 34 in Ll and positions 72, 78 and 84 in FR3. The Serogroup I specificity may be associated with Glu 84. The Serogroup II specificity may be associated with Thr 78 and Ala 84. Asn 34 cannot be ruled out completely. The extent to which certain serogroup-associated residues contribute to the V_κ21 antigenic determinants was assessed by constructing molecular models of V region domains. These demonstrated that the side-chains at positions 78 and 84 were close to the surface of the molecule, and suggested that the shape of these side-chains might not be the major factor in forming the serogroup specificities. Consequently, serogroup-associated residues seem to contribute either individually or in certain combinations to the determinants(s).     

Activation-induced cytidine deaminase structure and functions: a species comparative view

In the ten years since the discovery of activation-induced cytidine deaminase (AID) there has been considerable effort to understand the mechanisms behind this enzyme's ability to target and modify immunoglobulin genes leading to somatic hypermutation and class switch recombination. While the majority of research has focused on mouse and human models of AID function, work on other species, from lamprey to rabbit and sheep, has taught us much about the scope of functions of the AID mutator. This review takes a species-comparative approach to what has been learned about the AID mutator enzyme and its role in humoral immunity.     

Protection against malaria is conferred by passive transferring rabbit F(ab)(2)' antibody fragments, induced by Plasmodium falciparum MSP-1 site-directed designed pseudopeptide-BSA conjugates assessed in a rodent model

F(ab)₂′-immunoglobulin (Ig) fragments induced by site-directed designed immunogens are emerging as novel tools of potential utility in the treatment of clinical episodes of transmissible diseases such as malaria. Immunogens based on reduced amide pseudopeptides based on site-directed molecular modifications represent structural probes that could be considered as novel vaccine candidates, as we have previously demonstrated.We have obtained F(ab)₂′-Ig rabbit antibodies induced against the N-terminal sequence of the native Merozoite Surface Protein-1 (MSP-1) of Plasmodium falciparum and a set of five MSP-1-derived reduced amide pseudopeptides. Pseudopeptides were designed for inducing functional neutralizing mono-specific polyclonal antibodies with potential applications in the control of malaria. Following a classical enzyme immunoglobulin fractionation, F(ab)₂′-Ig fragments were tested for their ability to suppress blood-stage parasitemia by passive immunization in malaria-infected mice. Some of these fragments proved totally effective in suppressing a lethal blood-stage challenge infection and others reduced malarial parasitemia.These data suggest that protection against Plasmodium yoelii malaria following passive transfer of structurally well-defined β-strand F(ab)₂′-Ig fragments can be associated with specific immunoglobulins induced by site-directed designed MSP-1 reduced amide pseudopeptides.     

Teleost IgSF immunoregulatory receptors

In all animals innate immunity is the first line of immune defense from invading pathogens. The prototypical innate cellular responses such as phagocytosis, degranulation, and cellular cytotoxicity are elicited by leukocytes in a diverse range of animals including fish, amphibians, birds and mammals reinforcing the importance of such primordial defense mechanisms. In mammals, these responses are intricately controlled and coordinated at the cellular level by distinct subsets of immunoregulatory receptors. Many of these surface proteins belong to the immunoglobulin superfamily and in mammals elaborate immunoregulatory receptor networks play a major role in the control of infectious diseases. Recent examination of teleost immunity has begun to further illustrate the complexities of these receptor networks in lower vertebrates. However, little is known about the mechanisms that control how immunoregulatory receptors influence cellular decision making in ectothermic vertebrates. This review focuses on several families of recently discovered immunoglobulin superfamily members in fish that share structural, phylogenetic and in some cases functional relationships with mammalian immunoregulatory receptors. Further characterization of these teleost innate immune receptor families will provide detailed information regarding the conservation and importance of innate immune defense strategies throughout vertebrate evolution.