Malaria represents a major cause of death from infectious disease. Hemozoin is a Plasmodium-derived product that contributes to progression of cerebral malaria. However, there is a gap of knowledge regarding how hemozoin is recognized by innate immunity. Myeloid C-type lectin receptors (CLRs) encompass a family of carbohydrate-binding receptors that act as pattern recognition receptors in innate immunity. In the present study, we identify the CLR CLEC12A as a receptor for hemozoin. Dendritic cell-T cell co-culture assays indicate that the CLEC12A/hemozoin interaction enhances CD8+ T cell cross-priming. Using the Plasmodium berghei Antwerpen-Kasapa (ANKA) mouse model of experimental cerebral malaria (ECM), we find that CLEC12A deficiency protects mice from ECM, illustrated by reduced ECM incidence and ameliorated clinical symptoms. In conclusion, we identify CLEC12A as an innate sensor of plasmodial hemozoin.

A Q fever outbreak on a dairy goat and cattle farm was investigated with regard to the One Health concept. Serum samples and vaginal swabs from goats with different reproductive statuses were collected. Cows, cats, and a dog were investigated with the same sample matrix. The farmer’s family was examined by serum samples. Ruminant sera were analyzed with two phase-specific enzyme-linked immunoassays (ELISAs). Dominant immunoglobulin G (IgG) phase II levels reflected current infections in goats. The cows had high IgG phase I and II levels indicating ongoing infections. Feline, canine, and human sera tested positive by indirect fluorescent antibody test (IFAT). Animal vaginal swabs were analyzed by qPCR to detect C. burnetii, and almost all tested positive. A new cattle-associated C. burnetii genotype C16 was identified by the Multiple-Locus Variable-number tandem repeat Analysis (MLVA/VNTR) from ruminant samples. Additionally, a possible influence of 17ß-estradiol on C. burnetii antibody response was evaluated in goat sera. Goats in early/mid-pregnancy had significantly lower levels of phase-specific IgGs and 17ß-estradiol than goats in late pregnancy. We conclude that the cattle herd may have transmitted C. burnetii to the pregnant goat herd, resulting in a Q fever outbreak with one acute human case. The influence of placentation and maternal pregnancy hormones during pregnancy on the immune response is discussed.

Dendritic cells (DCs) and natural killer (NK) cells are critically involved in the early response against various bacterial microbes. Functional activation of infected DCs and NK cell-mediated gamma interferon (IFN-γ) secretion essentially contribute to the protective immunity against Chlamydia . How DCs and NK cells cooperate during the antichlamydial response is not fully understood.

We present a new and straightforward method by which standard cell culture plates can be sealed off from ambient air and be placed under controlled hypoxic cell culture conditions without costly or highly specialized materials. The method was established on a murine cell culture system using the dendritic cell line JAWS II but can be readily adapted to other cell cultures. The procedure was designed to be easy to implement in cell culture laboratories with standard incubators and requires only readily available materials, resources, and consumables, such as six-well plates, degassed culture medium, CoCl₂, a vacuum sealer, etc., and no further complicated laboratory equipment. The simple hypoxic cell culture method presented here is technically reliable and experimentally safe. As it can be performed in any standard incubator, it is suitable for use at both low and higher biosafety levels.

An inactivated Coxiella burnetii Phase I (PhI) vaccine (Coxevac®) is licensed in several European countries for goats and cattle to prevent coxiellosis. The vaccine is also applied to sheep, although detailed information about the ovine immune response and vaccine dose is missing. Eighteen gimmers from a C. burnetii unsuspected flock were randomly divided into three groups of six. Group 1 (Cox1) and 2 (Cox2) were vaccinated twice with 1 ml and 2 ml Coxevac®, respectively, three weeks apart (primary vaccination). The same procedure was applied with Cox3 (2 ml sodium chloride, control group). A third injection (booster) was performed after nine months. Potential side effects were determined by measuring the rectal body temperature and skin thickness at the injection site. Blood samples were collected to detect phase-specific IgM and IgG antibodies and interferon-ɣ (IFN-ɣ) release by immunofluorescence assay and ELISAs, respectively. Moreover, a cell infection neutralization assay determined the appearance of neutralizing sera. Body temperatures increased for one day post vaccination, and the skin swelled only slightly. Regardless of the vaccine volume, immunized sheep reacted first with an IgM and IgG PhII response. Ten weeks after the primary vaccination, IgG PhI antibodies predominated. Boosting eight months after primary vaccination resulted in a robust IgG PhI increase and strong IFN-ɣ response. In the vaccinated animals, the neutralizing effect is more widespread after the administration of 1 ml than after the treatment with 2 ml. In summary, differences between 1 and 2 ml Coxevac® are minor, and a vaccine volume of 1 ml seems to be sufficient. A booster after the primary vaccination is apparently necessary to stimulate the cell-mediated immune response in naïve sheep.