The legacy of ZikaPLAN: a transnational research consortium addressing Zika

Global health research partnerships with institutions from high-income countries and low- and middle-income countries are one of the European Commission's flagship programmes. Here, we report on the ZikaPLAN research consortium funded by the European Commission with the primary goal of addressing the urgent knowledge gaps related to the Zika epidemic and the secondary goal of building up research capacity and establishing a Latin American-European research network for emerging vector-borne diseases. Five years of collaborative research effort have led to a better understanding of the full clinical spectrum of congenital Zika syndrome in children and the neurological complications of Zika virus infections in adults and helped explore the origins and trajectory of Zika virus transmission. Individual-level data from ZikaPLAN`s cohort studies were shared for joint analyses as part of the Zika Brazilian Cohorts Consortium, the European Commission-funded Zika Cohorts Vertical Transmission Study Group, and the World Health Organization-led Zika Virus Individual Participant Data Consortium. Furthermore, the legacy of ZikaPLAN includes new tools for birth defect surveillance and a Latin American birth defect surveillance network, an enhanced Guillain-Barre Syndrome research collaboration, a de-centralized evaluation platform for diagnostic assays, a global vector control hub, and the REDe network with freely available training resources to enhance global research capacity in vector-borne diseases.

The molecular characterisation of Giardia from dogs in southern Germany

Faecal samples were obtained randomly from asymptomatic dogs visiting veterinary clinics (kept individually) and sanctuaries (kept in groups) in southern Germany. Of 60 Giardia positive samples, 55 samples successfully amplified at the 18S rDNA locus. In both dogs kept individually and dogs kept in groups, assemblage A was most prevalent (overall, n=33, 60%), followed by mixed infections with assemblages A&C (overall, n=15, 27.3%), while assemblages C&D alone were less often detected (overall, n=5, 9.1% and n=2, 3.6%). The occurrence of zoonotic genotypes was more prevalent in individual than in group dogs. Genotyping at the gdh locus confirmed the 18S results and clustered the assemblage A isolates into A-I. This is the first large-scale urban survey in Central Europe, which has not only confirmed the high prevalence of Giardia in asymptomatic domestic dogs, but has also shown that the zoonotic assemblage A occurs commonly in domestic dogs living in urban environments, and more frequently than the dog-specific assemblage. Although it was not possible to obtain samples from pet owners in this study, the results demonstrate that a significant proportion of dogs in urban areas of southern Germany harbour zoonotic Giardia, and should thus be considered a potential reservoir for infection in humans.

Spatial distribution of GABA(B)R1 receptor mRNA and binding sites in the rat brain

A gamma-aminobutyric acid (GABA)(B) receptor (named GABA(B)R1) has been recently cloned in the rat and human brain and two variants generated by alternative RNA splicing were identified. In the present study, we addressed the question as to whether these variants contribute to the diversity of GABA(B) receptor-mediated physiological responses and constitute real receptor subtypes with distinct functions. To this aim, we have mapped the GABA(B)R1 (R1a) and GABA(B)R1b (R1b) transcript distribution in the rat brain using in situ hybridization. We have compared the mRNA distribution with the distribution of [(3)H]CGP54626-labeled binding GABA(B)R1 receptor sites as assessed in adjacent cryosections by quantitative autoradiography. We found that GABA(B) receptor transcripts and binding sites are expressed in the brain in almost all neuronal cell populations. Expression in glial cells, if any, is marginal. We observed a good parallelism between GABA(B)R1 mRNA transcripts and binding sites in broad neuroanatomical entities with highest densities in hippocampus, thalamic nuclei, and cerebellum. By contrast, R1a and R1b transcripts exhibit marked differences in their regional and cellular distribution pattern. A typical example is the cerebellum with an almost exclusive expression of R1b in the Purkinje cells and of R1a in the granule, stellate, and basket cells. Data pointing at a pre- versus postsynaptic localization for R1a and R1b, respectively, at some neuronal sites are presented.

Human gamma-aminobutyric acid type B receptors are differentially expressed and regulate inwardly rectifying K+ channels

gamma-Aminobutyric acid type B receptors (GABABRs) are involved in the fine tuning of inhibitory synaptic transmission. Presynaptic GABABRs inhibit neurotransmitter release by down-regulating high-voltage activated Ca2+ channels, whereas postsynaptic GABABRs decrease neuronal excitability by activating a prominent inwardly rectifying K+ (Kir) conductance that underlies the late inhibitory postsynaptic potentials. Here we report the cloning and functional characterization of two human GABABRs, hGABABR1a (hR1a) and hGABABR1b (hR1b). These receptors closely match the pharmacological properties and molecular weights of the most abundant native GABABRs. We show that in transfected mammalian cells hR1a and hR1b can modulate heteromeric Kir3.1/3.2 and Kir3.1/3.4 channels. Heterologous expression therefore supports the notion that Kir3 channels are the postsynaptic effectors of GABABRs. Our data further demonstrate that in principle either of the cloned receptors could mediate inhibitory postsynaptic potentials. We find that in the cerebellum hR1a and hR1b transcripts are largely confined to granule and Purkinje cells, respectively. This finding supports a selective association of hR1b, and not hR1a, with postsynaptic Kir3 channels. The mapping of the GABABR1 gene to human chromosome 6p21.3, in the vicinity of a susceptibility locus (EJM1) for idiopathic generalized epilepsies, identifies a candidate gene for inherited forms of epilepsy.

Effects of parathyroid hormone and parathyroid hormone-related protein on the rates of absorption of magnesium, calcium, sodium, potassium and phosphate ions from the reticulo-rumen of sheep

Not only parathyroid hormone (PTH) but also parathyroid hormone-related protein (PTHrP) may play a role in calcium and phosphate homeostasis in ruminants. In five trained sheep, each with a large rumen cannula, the isolated rumen wash technique was used to measure electrolyte absorption rates from the rumen. After two control periods of measurement, 20 micrograms PTH(1-34) (n = 4), or PTHrP(1-34) (n = 5), was injected intravenously as a loading dose, followed by an infusion of 0.67 micrograms min-1 over 2 h. Both PTH(1-34) and PTHrP(1-34) significantly increased the absorption rates of calcium and phosphate from the reticulo-rumen. The increases in the absorption rates of magnesium, sodium and potassium observed were not significant. The same technique was also used to demonstrate that increasing the intraruminal calcium concentration from 1 to 4 mmol l(-1) caused corresponding increases in the net rate of absorption of both calcium and inorganic phosphate from the reticulo-rumen. Rumen epithelium was taken from four sheep and mounted in Ussing chambers so that fluxes of calcium could be measured in both directions using 45Ca. It was found that the addition of 100 ng ml-1 PTH(1-34) or PTHrP(1-34) to the serosal side increased the net calcium flux rates across the ruminal epithelium. It is concluded that both PTH and PTHrP can influence calcium and phosphate homeostasis in sheep not only by their recognized actions on bone and kidney but also on the absorption of these ions from the forestomachs.