Biosensor immunoassay for traces of hazelnut protein in olive oil

The fraudulent addition of hazelnut oil to more expensive olive oil not only causes economical loss but may also result in problems for allergic individuals as they may inadvertently be exposed to potentially allergenic hazelnut proteins. To improve consumer safety, a rapid and sensitive direct biosensor immunoassay, based on a highly specific monoclonal antibody, was developed to detect the presence of hazelnut proteins in olive oils. The sample preparation was easy (extraction with buffer); the assay time was fast (4.5 min only) and the limit of detection was low (0.08 μg/g of hazelnut proteins in olive oil). Recoveries obtained with an olive oil mixed with different amounts of a hazelnut protein containing hazelnut oil varied between 93% and 109%

Modeling long-term malaria transmission changes in a Tanzanian village using cross-sectional data on age specific prevalence and levels of antibodies.

Robust estimates of Plasmodium falciparum transmission intensity are imperative for planning, implementation and evaluation of malaria control interventions. Seroconversion rates (SCR) to asexual blood-stage antigens can provide estimates of transmission intensity that correlate with entomological inoculation rates. We study past transmission trends in a rural village and evaluate new models to improve SCR based methods by analysis of antibody levels from multiple cross-sectional serological surveys. The study was conducted in Nyamisati, Rufiji, Tanzania, where parasite prevalence decreased from 65 to 18% from 1999 and 2010. A single intervention with ITNs was performed in 1999. IgG levels to recombinant P. falciparum antigens (MSP-119, MSP-2, MSP-3, AMA-1) and An. gambiae salivary protein gSG6 were measured in children (1-16y) sampled in cross-sectional surveys in 1999 and 2010. SCR and rates of antibody decay were estimated by fitting mathematical models to data from the two cross-sections, assuming three profiles of exposure: (i) stable; (ii) stepwise decrease; or (iii) continuous decrease. Results suggest an average 66% decrease in malaria transmission intensity and an 89% reduction in Anopheles exposure. Transmission trends were best described by a stepwise decrease model with a reduction predicted to occur shortly after distribution of ITNs. The new models provide estimates of the duration of antibody responses under this transmission decline. MSP-119 seropositive individuals were estimated to convert to seronegative with a half-life of 12 (95% CI 7-20) years due to antibody decline with a half-life of 3 (95% CI 2-6) years. The reduction in transmission may in part be attributed to reduced anopheles exposure following the introduction of ITNs, but is not likely to be explained by ITNs alone. Despite reduced parasite prevalence many children remained seropositive to blood-stage antigens. The new sensitive models using antibody levels enabled detection of reduced exposure among seropositive children and provided estimates of both antibody and transmission dynamics

Evaluating changing malaria transmission in a rural village, in coastal Tanzania, by assessment of IgG antibodies against Plasmodium falciparum and Anopheles gambiae antigens

The changing epidemiology of malaria in Sub-Saharan Africa over the last decade needs further understanding. A longitudinal project on the epidemiology of malaria was set up in the Nyamisati village, Rufiji District, Tanzania in 1985. Cross-sectional surveys have revealed a gradual decrease in parasite prevalence over the last 25 years, from >90% to 13% (by PCR), despite the absence of large scale control interventions. Although PCR provides good detection of low level parasitemia, assessment of parasite prevalence alone may not fully reflect the level of exposure in a population. In order to further understand the long-term dynamics of malaria transmission in this setting, we combined an assessment of parasite prevalence with analyses of IgG antibodies against antigens of the P. falciparum parasite and a salivary antigen of the Anopheles vector. The study included children 1–16 years old participating in cross-sectional surveys in Nyamisati village in 1995, 1999 and 2010. Parasite prevalence was established by PCR. Detection and quantification of IgG antibodies against P. falciparum crude schizont extract (PfSE) and Anopheles gambiae salivary gland protein 6 (gSG6) were performed with enzyme-linked immunosorbent assay (ELISA). Levels of IgG antibodies against merozoite surface protein 1–19 (MSP-119) and merozoite surface protein 2 (MSP-2) were assessed using a multiplexed bead-based immunoassay. Parasite prevalence and the prevalence and levels of IgG antibodies against PfSE, MSP-119 and MSP-2 decreased between 1999 and 2010, with the most marked reduction among the youngest children (1–4 years of age). The prevalence and levels of anti-gSG6 IgG antibodies showed a similar pattern. These findings suggest a substantially decreased intensity of malaria transmission in the Nyamisati area over the past 10 years, together with an evident decrease in the population level of exposure to the malaria vector