Low seroprevalence of antibodies to Neospora caninum in wild canids in Israel.

The role of domestic dogs in the epidemiology of Neospora caninum as well as the relationship between N. caninum infection of farm dogs and cattle were demonstrated, however, evidence is scarce regarding the role of wild canids in domestic animal neosporosis. The present study was undertaken to evaluate the role of wild canids in the epidemiology of bovine neosporosis in Israel by analyzing the prevalence of antibodies to N. caninum in wild canids. Sera samples were collected from 114 free ranging wild golden jackals (Canis aureus), 24 red foxes (Vulpes vulpes) and nine wolves (Canis lupus), which were collected in Israel during the years 1999-2004. Of a total of 147 wild canids tested antibodies to N. caninum were only found in two golden jackals with IFAT titers of 1:50, and in one red fox and one wolf with IFAT titer of 1:400. The low seroprevalence found in this study (2.7%) indicated that wild canids probably do not have an important role in the epidemiology of N. caninum in Israel. However, since the diet of different species of wild canids and even diverse populations of the same canid species vary, it is possible that other results might be obtained from specific wild canids populations, which scavenge in the vicinity of infected bovines.

Evaluation of a dot ELISA kit for measuring immunoglobulin M antibodies to canine parvovirus and distemper virus.

A dot ELISA for the detection of immunoglobulin M (IgM) antibodies to canine distemper virus (CDC) and canine parvovirus (CPV) was assessed. The titres of IgM antibodies to CDV and CPV in 100 dogs were measured by the Immunocomb ELISA kit and compared with the results derived from the immunofluorescence assay (IFA). There was a strong correlation between the results of the dot ELISA technique and the IFA (P < 0.001). The dot ELISA kit was also used to assess the changes in the levels of immunoglobulin G (IgG) and IgM antibodies to CPV and CDV in 10 puppies vaccinated with a polyvalent vaccine. High levels of IgM antibodies to CPV were first detected seven days after they were vaccinated, and after nine days all the pups had high titres of IgG antibodies to CPV. High levels of IgM antibodies to CDV were detected after nine days and the highest average titres were recorded after 12 days. IgG antibodies to CDV were present from nine days after vaccination.

Generation of biologically active anti-Cryptococcus neoformans IgG, IgE and IgA isotype switch variant antibodies by acridine orange mutagenesis.

Administration of MoAbs to Cryptococcus neoformans capsular glucuronoxylomannan (GXM) can alter the course of infection in mouse models. However, the effectiveness of these antibodies appears to depend on isotype and specificity. Comparison of isotype protection efficacy requires families of MoAbs with identical fine specificity and different constant region domain. The generation of such families by hybridoma technology is not always possible because the immune response produces MoAbs of limited classes or subclasses. In these instances isotype switch variants can be isolated in vitro. Unfortunately, standard methods of recovering spontaneous switch variants are often unsuccessful, mainly because of the low frequency of switching. In this study we demonstrate that acridine orange stimulation of an IgG3 anti-C. neoformans-producing hybridoma can be used to recover the entire set of isotype switch variants: IgGl, IgG2b, IgG2a, IgE and IgA. All isotype switch variants bind to GXM; fine specificity mapping, using an 11 amino acid peptide polysaccharide mimetope, revealed conservation of binding site specificity. Furthermore, all isotype switch variants reacted with an anti-idiotopic MoAb. The functional activity of this set of MoAbs was demonstrated by their ability to enhance phagocytosis and antifungal efficacy of human macrophage-like THP-1 cells, with IgG3 being the most effective and IgE being the least effective.

A new type of G-->A hypermutation affecting human immunodeficiency virus.

A form of G-->A hypermutation preferentially affecting GA dinucleotides of genomic RNA has been found to occur in retroviral systems ("type 1"). In a detailed longitudinal study of an AIDS patient we have observed a new type of G-->A hypermutation, which preferentially affects one or more 5' G residues in runs of G's. HIV-1 proviral DNA samples obtained at widely separate times during this patient's course contained representatives of this type of G-->A hypermutation, designated "type 2." We propose that G-->A hypermutation is caused by a mutated form of the HIV-1 reverse transcriptase; and that hypermutated DNA may persist for long periods in infected patients, perhaps as proviral DNA in long-lived cell lineages. Like type 1 G-->A hypermutation, type 2 G-->A hypermutation may contribute to the heterogeneity of replicating pools of HIV by recombination.