Studies on Host-Related Pathogenesis of Herpes simplex Type-1 Encephalitis in Rat

In order to explore the molecular mechanisms of Herpes simplex encephalitis (HSE), a severe infection of the central nervous system (CNS) caused by Herpes simplex type 1 virus (HSV-1); a rat model resembling the human condition was characterized in the DA (Dark Agouti) strain. After injection into the whiskers’ area HSV-1 entered the CNS at the level of the brain stem via the trigeminal ganglion, subsequently spreading to the thalamus, cortex and olfactory bulb, leading to death at five days post infection (dpi). In contrast, the Piebald Virol Glaxo (PVG) strain was found to be completely resistant to disease and without signs of immunological reactions within the CNS, since HSV-1 virus did not penetrate beyond the site of inoculation. The kinetics of HSV-1 infection in the two strains was thoroughly characterized by magnetic resonance imaging, quantitative polymerase chain reaction, virus isolation in green monkey kidney cells, histology and immunohistochemistry (IHC). Kinetics of virus propagation and primary immune reactions following HSV-1 infection were compared between the susceptible DA and the resistant PVG strain at 12 hours post-infection (hpi), 1, 2, 3 and 4 dpi. A low expression of Toll-like receptors 2 and 9 and slower recruitment of macrophages was associated with viral replication in the perineurial cell layer and consecutive propagation to the CNS in the DA rats, while virus spread was confined to the epineurium of the peripheral nerve in the resistant PVG strain. The underlying genetic mechanisms for the difference in susceptibility between the two strains were dissected in a F2 (DAxPVG) intercross, with genome-wide microsatellite-based genotyping. Linkage analysis revealed a very strong quantitative trait locus (QTL) on chromosome 4 regulating susceptibility to HSE. Fine mapping of the QTL by infection of additional rats with recombinations in the region, haplotype mapping of disease susceptibility in a panel of inbred rat strains, infection of congenic strains, sequencing and mRNA expression studies of the genes in the interval indicated the calcitonin receptor (Calcr) as the candidate gene. Functional experiments with treatment using calcitonin receptor agonists in vivo provided further support of the candidate gene status of Calcr. Additional genetic determinants of susceptibility to HSE were studied in two other rat strains: Spontaneously Hypertensive Rat (SHR) and Brown Norway (BN), which are susceptible and resistant, respectively, to HSE, as well as in 29 BNxSHR recombinant inbred lines (RIL). The use of an already existing database of single nucleotide polymorphisms (SNPs) differing between SHR and BN revealed another significant QTL on chromosome 4 regulating susceptibility to HSE. Further analysis of the QTL using immunohistopathology indicated the Von Willebrand Factor homologue (Vwf) gene, which has a role in blood-brain-barrier homeostasis, as a possible candidate for regulating differences in susceptibility between the BN and SHR strains. In summary, the present study has demonstrated a strong genetic influence on the susceptibility to HSE in a rat model that displays many similarities to the corresponding human condition. Further genetic and functional studies are needed to confirm the candidate gene status of Calcr and Vwf regulating HSE and these may ultimately lead to more effective treatments of this severe CNS infection

The Calcitonin Receptor Gene Is a Candidate for Regulation of Susceptibility to Herpes simplex Type 1 Neuronal Infection Leading to Encephalitis in Rat

Herpes simplex encephalitis (HSE) is a fatal infection of the central nervous system (CNS) predominantly caused by Herpes simplex virus type 1. Factors regulating the susceptibility to HSE are still largely unknown. To identify host gene(s) regulating HSE susceptibility we performed a genome-wide linkage scan in an intercross between the susceptible DA and the resistant PVG rat. We found one major quantitative trait locus (QTL), Hse1, on rat chromosome 4 (confidence interval 24.3–31 Mb; LOD score 29.5) governing disease susceptibility. Fine mapping of Hse1 using recombinants, haplotype mapping and sequencing, as well as expression analysis of all genes in the interval identified the calcitonin receptor gene (Calcr) as the main candidate, which also is supported by functional studies. Thus, using unbiased genetic approach variability in Calcr was identified as potentially critical for infection and viral spread to the CNS and subsequent HSE development

Influence of Perineurial Cells and Toll-Like Receptors 2 and 9 on Herpes simplex Type 1 Entry to the Central Nervous System in Rat Encephalitis

Herpes simplex encephalitis (HSE) is a rare disease with high mortality and significant morbidity among survivors. We have previously shown that susceptibility to HSE was host-strain dependent, as severe, lethal HSE developed after injection of human Herpes simplex type 1 virus (HSV-1) into the whiskers area of DA rats, whereas PVG rats remained completely asymptomatic. In the present study we investigated the early immunokinetics in these strains to address the underlying molecular mechanisms for the observed difference. The virus distribution and the immunological responses were compared in the whiskers area, trigeminal ganglia and brain stem after 12 hours and the first four days following infection using immunohistochemistry and qRT-PCR. A conspicuous immunopathological finding was a strain-dependent difference in the spread of the HSV-1 virus to the trigeminal ganglia, only seen in DA rats already from 12 hpi. In the whiskers area infected perineurial cells were abundant in the susceptible DA strain after 2 dpi, whereas in the resistant PVG rats HSV-1 spread was confined only to the epineurium. In both strains activation of Iba1+/ED1+ phagocytic cells followed the distribution pattern of HSV-1 staining, which was visible already at 12 hours after infection. Notably, in PVG rats higher mRNA expression of Toll-like receptors (Tlr) -2 and -9, together with increased staining for Iba1/ED1 was detected in the whiskers area. In contrast, all other Tlr-pathway markers were expressed at higher levels in the susceptible DA rats. Our data demonstrate the novel observation that genetically encoded properties of the host nerve and perineurial cells, recruitment of phagocyting cells together with the low expression of Tlr2 and -9 in the periphery define the susceptibility to HSV-1 entry into the nervous system

Von Willebrand Factor Gene Variants Associate with Herpes simplex Encephalitis

Herpes simplex encephalitis (HSE) is a rare complication of Herpes simplex virus type-1 infection. It results in severe parenchymal damage in the brain. Although viral latency in neurons is very common in the population, it remains unclear why certain individuals develop HSE. Here we explore potential host genetic variants predisposing to HSE. In order to investigate this we used a rat HSE model comparing the HSE susceptible SHR (Spontaneously Hypertensive Rats) with the asymptomatic infection of BN (Brown Norway). Notably, both strains have HSV-1 spread to the CNS at four days after infection. A genome wide linkage analysis of 29 infected HXB/BXH RILs (recombinant inbred lines-generated from the prior two strains), displayed variable susceptibility to HSE enabling the definition of a significant QTL (quantitative trait locus) named Hse6 towards the end of chromosome 4 (160.89-174Mb) containing the Vwf (von Willebrand factor) gene. This was the only gene in the QTL with both cis-regulation in the brain and included several non-synonymous SNPs (single nucleotide polymorphism). Intriguingly, in human chromosome 12 several SNPs within the intronic region between exon 43 and 44 of the VWF gene were associated with human HSE pathogenesis. In particular, rs917859 is nominally associated with an odds ratio of 1.5 (95% CI 1.11-2.02; p-value = 0.008) after genotyping in 115 HSE cases and 428 controls. Although there are possibly several genetic and environmental factors involved in development of HSE, our study identifies variants of the VWF gene as candidates for susceptibility in experimental and human HSE

Fullkorn: ett rent hel-vete i vardagen : En studie om fullkornskonsumtion bland vuxna mellan 18–44 år i Sverige

SAMMANFATTNING Introduktion: Endast 12 procent av befolkningen i Sverige konsumerar den rekommenderade dagliga mängden av fullkorn regelbundet. Lägst konsumtion observeras bland vuxna i åldern 18–44 år. Fullkornsintag kan studeras genom Health Action Process Approach (HAPA), en modell för att granska motiverande och viljedrivna processer som bidrar till olika hälsobeteenden. Syfte: Studiens syfte undersöka self-efficacy, riskperception, planering och förväntat resultat i relation till konsumtion av fullkorn hos vuxna i åldern 18-44 år. Metod: Tvärsnittsstudie. Insamling av data har övervägande skett inom Uppsala och Stockholm, genom en digital enkät. Svar analyserades från totalt 67 deltagare, på frågor om fullkornsintag och mekanismer kring fullkornskonsumtion, utarbetade i enlighet med HAPA-modellen. Enkäten innefattade svarsalternativ av typerna flerval, graderingsskalor och fritextsvar. Resultat: Deltagarna ansåg sig själva besitta self-efficacy och kapacitet att hantera hinder, så länge det eftersträvade hälsobeteendet inte medför en högre kostnad eller svårigheter att implementera beteendet i deras vardagliga rutin. Trots detta planerade endast 20 % av dem sitt intag av fullkornsprodukter. Fullkornsgröt utgjorde den största och mest frekventa källan till fullkorn, följt av mjukt fullkornsbröd. Majoriteten av deltagarna var omedvetna om potentiella hälsorisker relaterade till bristande fullkornskonsumtion. Insamlade resultat visar att 75 % av deltagarna inte nådde upp till aktuella rekommendationer kring fullkornsintag. Slutsats: Bristande medvetenhet kring hälsorisker förknippade med ett lågt fullkornsintag samt otillräcklig planering förefaller vara ett betydande hinder för målgruppens konsumtion av fullkorn. Överlag ansåg sig deltagarna besitta self-efficacy och kapacitet att hantera hinder enligt HAPA, denna tro på self-efficacy avspeglades dock inte av individernas fullkornskonsumtion

Fullkorn: ett rent hel-vete i vardagen : En studie om fullkornskonsumtion bland vuxna mellan 18–44 år i Sverige

SAMMANFATTNING Introduktion: Endast 12 procent av befolkningen i Sverige konsumerar den rekommenderade dagliga mängden av fullkorn regelbundet. Lägst konsumtion observeras bland vuxna i åldern 18–44 år. Fullkornsintag kan studeras genom Health Action Process Approach (HAPA), en modell för att granska motiverande och viljedrivna processer som bidrar till olika hälsobeteenden. Syfte: Studiens syfte undersöka self-efficacy, riskperception, planering och förväntat resultat i relation till konsumtion av fullkorn hos vuxna i åldern 18-44 år. Metod: Tvärsnittsstudie. Insamling av data har övervägande skett inom Uppsala och Stockholm, genom en digital enkät. Svar analyserades från totalt 67 deltagare, på frågor om fullkornsintag och mekanismer kring fullkornskonsumtion, utarbetade i enlighet med HAPA-modellen. Enkäten innefattade svarsalternativ av typerna flerval, graderingsskalor och fritextsvar. Resultat: Deltagarna ansåg sig själva besitta self-efficacy och kapacitet att hantera hinder, så länge det eftersträvade hälsobeteendet inte medför en högre kostnad eller svårigheter att implementera beteendet i deras vardagliga rutin. Trots detta planerade endast 20 % av dem sitt intag av fullkornsprodukter. Fullkornsgröt utgjorde den största och mest frekventa källan till fullkorn, följt av mjukt fullkornsbröd. Majoriteten av deltagarna var omedvetna om potentiella hälsorisker relaterade till bristande fullkornskonsumtion. Insamlade resultat visar att 75 % av deltagarna inte nådde upp till aktuella rekommendationer kring fullkornsintag. Slutsats: Bristande medvetenhet kring hälsorisker förknippade med ett lågt fullkornsintag samt otillräcklig planering förefaller vara ett betydande hinder för målgruppens konsumtion av fullkorn. Överlag ansåg sig deltagarna besitta self-efficacy och kapacitet att hantera hinder enligt HAPA, denna tro på self-efficacy avspeglades dock inte av individernas fullkornskonsumtion

Sequences of candidate genes.

<p>Schematic illustration of genomic DNA sequences of the <i>Ccdc132</i>, <i>Calcr</i> and <i>Tfpi2</i> genes showing some of the SNP variations in PVG.A rats. Black boxes represent the different exons in each gene; the arrows below represent SNPs in intronic regions; arrows above represent SNPs in exons and 5′ UTR regions.</p

Proline catabolism is a key factor facilitating Candida albicans pathogenicity

Candida albicans, the primary etiology of human mycoses, is well-adapted to catabolize proline to obtain energy to initiate morphological switching (yeast to hyphal) and for growth. We report that put1-/- and put2-/- strains, carrying defective Proline UTilization genes, display remarkable proline sensitivity with put2-/- mutants being hypersensitive due to the accumulation of the toxic intermediate pyrroline-5-carboxylate (P5C), which inhibits mitochondrial respiration. The put1-/- and put2-/- mutations attenuate virulence in Drosophila and murine candidemia models and decrease survival in human neutrophils and whole blood. Using intravital 2-photon microscopy and label-free non-linear imaging, we visualized the initial stages of C. albicans cells infecting a kidney in real-time, directly deep in the tissue of a living mouse, and observed morphological switching of wildtype but not of put2-/- cells. Multiple members of the Candida species complex, including C. auris, are capable of using proline as a sole energy source. Our results indicate that a tailored proline metabolic network tuned to the mammalian host environment is a key feature of opportunistic fungal pathogens