Reduced virulence of a pseudorabies virus isolate from wild boar origin in domestic pigs correlates with hampered visceral spread and age-dependent reduced neuroinvasive capacity

Morbidity and mortality associated with pseudorabies virus (PRV) infection are dependent on the age of the pig and the virulence of the strain. PRV strains circulating in wild boar are considered to be low virulent, but no mechanistic explanation for their reduced virulence is available. Here infection of 2-and 15-week-old domestic pigs with the PRV wild boar strain BEL24043 did not induce clinical symptoms in 15-week-old pigs, but resulted in important neurological and respiratory disease in 2-week-old piglets. A detailed study of the (neuro) pathogenesis and associated cytokine mRNA expression showed that the reduced virulence of the wild boar strain, compared to what was previously reported for the virulent domestic NIA3 strain, is due to a severely hampered spread to visceral organs in pigs of both age categories and to an efficient suppression of viral replication at primary replication sites of 15-week-old pigs and to a lesser extent in those of 2-week-old piglets. The age-dependent difference in induced symptoms seems to be due to an immature development state of the immune and/or nervous system in 2-week-old pigs. An extensive viral replication associated with a robust expression of cytokine-related mRNA was found in the olfactory bulb of 2-week-old piglets, correlating with observed neurological disease. Neuroinvasion also occurred via the trigeminal route in 2-week-old pigs, but viral replication was efficiently suppressed in the trigeminal ganglion in the presence of a moderate induction of cytokine-related mRNA. Viral replication in the peripheral and central nervous system of 15-week-old pigs was limited and efficiently suppressed

Age-dependent differences in pseudorabies virus neuropathogenesis and associated cytokine expression

The severity of clinical symptoms induced by pseudorabies virus (PRV) infection of its natural host is inversely related to the age of the pig. During this study, 2- and 15-week-old pigs were inoculated with PRV strain NIA3. This resulted in important clinical disease, although the associated morbidity and mortality were lower in older pigs. Quantitative PCR analysis of viral DNA in different organs confirmed the general knowledge on PRV pathogenesis. Several new findings and potential explanations for the observed age-dependent differences in virulence, however, were determined from the study of viral and cytokine mRNA expression at important sites of neuropathogenesis. First, only limited viral and cytokine mRNA expression was detected in the nasal mucosa, suggesting that other sites may serve as the primary replication site. Second, PRV reached the trigeminal ganglion (TG) and brain stem rapidly upon infection but, compared to 2-week-old pigs, viral replication was less pronounced in 15week- old pigs, and the decrease in viral mRNA expression was not preceded by or associated with an increased cytokine expression. Third, extensive viral replication associated with a robust expression of cytokine mRNA was detected in the olfactory bulbs of pigs from both age categories and correlated with the observed neurological disease. Our results suggest that age-dependent differences in PRV-induced clinical signs are probably due to enhanced viral replication and associated immunopathology in immature TG and the central nervous system neurons of 2-week-old pigs and that neurological disease is related with extensive viral replication and an associated immune response in the olfactory bulb. IMPORTANCE : It is well known that alphaherpesvirus infections of humans and animals result in more severe clinical disease in newborns than in older individuals and that this is probably related to differences in neuropathogenesis. The underlying mechanisms, however, remain unclear. Pseudorabies virus infection of its natural host, the pig, provides a suitable infection model to study this more profoundly. We show here that the severe neurological disease observed in 2-week-old pigs does not appear to be related to a hampered innate immune response but is more likely to reflect the immature development state of the trigeminal ganglia (TG) and central nervous system (CNS) neurons, resulting in an inefficient suppression of viral replication. In 15-week-old pigs, viral replication was efficiently suppressed in the TG and CNS without induction of an extensive immune response. Furthermore, our results provide evidence that neurological disease could, at least in part, be related to viral replication and associated immunopathology in the olfactory bulb

New therapeutic targets for the treatment of erectile dysfunction

Introduction. Despite the high efficacy and safety rates of the currently available treatments for erectile dysfunction, basic research reveals numerous new targets that are explored for therapeutic use. Aim. To overview potential new targets and to review available animal and human studies focusing on the potential of these targets for effective therapy for treating erectile dysfunction. Methods. A comprehensive literature search was conducted using the PubMed and Medline database, and citations were selected based on relevance. Main Outcome Measures. Data are presented based on the analysis of the selected scientific information and published clinical trials. Results. Fundamental research has, in the past decade, increased the understanding in both the physiological and the pathophysiological pathways that play a role in erectile function. As this information increases each day, new targets to treat erectile dysfunction are frequently presented. Currently a number of new therapeutic targets have been published. Some of them target the nitric oxide/cyclic guanosine monophosphate relaxation pathway as the phosphodiesterase type 5 inhibitors do, others primarily target pathways involved in contraction. Also, targets within the central nervous system currently receive much attention. Some of these targets have already been used in clinical trials to test their efficacy and safety, with either disappointing or promising results. Conclusions. This review overviews potential therapeutic targets and summarizes animal as well as human studies evaluating their perspectives for the treatment of erectile dysfunction. Decaluwe K, Pauwels B, Verpoest S, and Van de Voorde J. New therapeutic targets for the treatment of erectile dysfunction

Pseudorabies virus isolates from domestic pigs and wild boars show no apparent in vitro differences in replication kinetics and sensitivity to interferon-induced antiviral status

Pseudorabies virus is the causative agent of Aujeszky's disease. Domestic pigs and wild boars are its natural hosts, and strains circulating within both populations differ in their capacity to induce clinical disease. Cell biological and molecular explanations for the observed differences in virulence are, however, lacking. Different virulence determinants that can be assessed in vitro were determined for five domestic swine strains, four wild boar strains and the NIA3 reference strain. Replication kinetics and plaque formation capacity in continuous swine testicular cells and different primary porcine cell lines were highly similar for isolates from both populations. Treatment of these cell lines with IFN alpha, IFN gamma or a combination of both provoked similar plaque-reducing effects for all strains. In conclusion, our results indicate that isolates from domestic swine and wild boar differ neither in intrinsic replication and dissemination capacity nor in sensitivity to antiviral effects of IFNs

Study on the involvement of soluble guanylyl cyclase and its different isoforms in carbon monoxide and carbon monoxide releasing molecule-2 induced vasodilatation

Besides nitric oxide, carbon monoxide (CO) also activates soluble guanylyl cyclase (sGC). CO as well as the CO-donor CORM-2 have been shown to possess vasodilatory properties. Whether these vasodilatory properties by CO can be attributed to sGC activation is still a matter of debate. The aim of this study was to examine the involvement of sGC and its different subunits in CO and CORM-2 induced vasodilatation within different vascular tissues. Isometric tension recordings were performed using mice isolated aortic rings, femoral artery ring segments as well as corpora cavernosa (CC). To be able to distinguish between the different sGC subunits we evaluated responses to saturated CO solutions and CORM-2 in both sGCa1-/- and sGCβ1KI/KI mice and their wild-type controls. Saturated CO solution was unable to relax mice isolated blood vessels, whereas it induced concentration-dependent relaxations in mice CC. In CC of wild-type mice, the response to CO was completely inhibited by the sGC inhibitor ODQ. The involvement of sGC in the CO-induced corporal relaxation was further confirmed by the loss of response to CO in CC isolated from sGCβ1KI/KI mice. Moreover, the vasodilatory responses of CO in the corporal tissue of sGCa1-/- mice were strongly inhibited although not completely abolished. In contrast to CO, CORM-2 was able to relax all vascular tissues examined in the present study, although ODQ only partially blocked the response to CORM-2 in the aorta. Interestingly ODQ did not affect the CORM-2 induced relaxation in the femoral arteries and the CC, indicating that sGC is not involved, which was confirmed using the transgenic mice. This study clearly illustrates that the molecular mechanism of CORM-2 induced vasorelaxation differs from that of CO induced vasorelaxation. While the CO induced vasorelaxation depends on activation of sGC, primarily the sGCa1β1 heterodimer, the vasorelaxing properties of CORM-2 are only partially dependent or even completely independent upon sGC activation. The observation that CO is more effective in relaxing CC tissues than other cardiovascular tissues investigated in the present study suggests that the heme-oxygenase/CO pathway may present a potential new target for therapeutic approaches towards erectile dysfunction

Age- and strain-dependent differences in the outcome of experimental infections of domestic pigs with wild boar pseudorabies virus isolates

Although pseudorabies virus (PRV) has been eradicated in domestic swine in many countries, its presence in wild boars remains a threat for a reintroduction into the currently unprotected swine population. To assess the possible impact of such a reintroduction in a naive herd, an in vivo infection study using two genetically characterized wild boar PRV isolates (BEL24043 and BEL20075) representative for wild boar strains circulating in south-western and central Europe and the virulent NIA3 reference strain was performed in 2- and 15-week-old domestic pigs. Our study revealed an attenuated nature of both wild boar strains in 15-week-old pigs. In contrast, it showed the capacity of strain BEL24043 to induce severe clinical symptoms and mortality in young piglets, thereby confirming that the known age dependency of disease outcome after PRV infection also holds for wild boar isolates. Despite the absence of clinical disease in 15-week-old sows, both wild boar PRV strains were able to induce seroconversion, but to a different extent. Importantly, differences in infection and transmission capacity of both strains were observed in 15-week-old sows. Strain BEL24043 induced a more prolonged and disseminated infection than strain BEL20075 and was able to spread efficiently to contact animals, indicative of its capacity to induce a sustained infection. In conclusion, it was shown that a reintroduction of a wild boar isolate into the domestic swine population could have serious economic consequences due to the induction of clinical symptoms in piglets and by jeopardizing the PRV-negative status