Serological study of hantavirus in man in the Autonomous Community of Madrid, Spain. (1/27)

Data relating to hantavirus infection in Spain are scarce and limited to rural areas. The aim of this work was to study the seroprevalence of hantavirus infection in the Autonomous Community of Madrid (ACM), a region containing both rural and urban populations in different ecological settings. Sera from 3852 individuals (1849 male, 2003 female) were screened by indirect inmunofluorescence, with Vero E6 cells infected with Puumala, Hantaan and Seoul viruses as antigens. Screen-positive results were confirmed by Western blot with recombinant Seoul virus nucleocapsid protein as antigen. Antibodies against hantavirus were detected in 12 sera (0.31%). No statistical differences were found according to sex and age. The highest prevalence was found in the southeastern area, significantly higher than the central and north-western areas. The most frequent serological pattern was reactivity against all three viruses used (33.3% of all positive sera). Therefore, this study confirms the presence of hantavirus infection in the ACM, including for the first time an urban area of Spain, but with the highest prevalence in a rural area. Serological evidence suggests that there is more than one circulating serotype.  (+info)

Use of vesicular stomatitis virus pseudotypes bearing hantaan or seoul virus envelope proteins in a rapid and safe neutralization test. (2/27)

A vesicular stomatitis virus (VSV) pseudotype bearing hantavirus envelope glycoproteins was produced and used in a neutralization test as a substitute for native hantavirus. The recombinant VSV, in which the enveloped protein gene (G) was replaced by the green fluorescent protein gene and complemented with G protein expressed in trans (VSVDeltaG*G), was kindly provided by M. A. Whitt. 293T cells were transfected with plasmids for the expression of envelope glycoproteins (G1 and G2) of HTNV or SEOV and were then infected with VSVDeltaG*G. Pseudotype VSV with the Hantaan (VSVDeltaG*-HTN) or Seoul (VSVDeltaG*-SEO) envelope glycoproteins were harvested from the culture supernatant. The number of infectious units (IU) of the pseudotype VSVs ranged from 10(5) to 10(6)/ml. The infectivity of VSVDeltaG*-HTN and VSVDeltaG*-SEO was neutralized with monoclonal antibodies, immune rabbit sera, and sera from patients with hemorrhagic fever with renal syndrome, and the neutralizing titers were similar to those obtained with native hantaviruses. These results show that VSVDeltaG*-HTN and -SEO can be used as a rapid, specific, and safe neutralization test for detecting hantavirus-neutralizing antibodies as an effective substitute for the use of native hantaviruses. Furthermore, the IU of VSVDeltaG*-HTN and -SEO did not decrease by more than 10-fold when stored at 4 degrees C for up to 30 days. The stability of the pseudotype viruses allows distribution of the material to remote areas by using conventional cooling boxes for use as a diagnostic reagent.  (+info)

Wounding: the primary mode of Seoul virus transmission among male Norway rats. (3/27)

In rodent populations, males are more likely to be infected with hantaviruses and to engage in aggression than are females. To assess the relationship between aggression and Seoul virus infection, Norway rats were trapped in Baltimore, Maryland and wounding, infection status, and steroid hormone concentrations were examined. Older males and males with high-grade wounds were more likely to have IgG antibody to Seoul, to shed virus in saliva, urine, and feces, and to have viral RNA in organs than either juveniles or adult males with less severe wounds. In contrast, neither age nor wounding predicted virus shedding among females. Although viral antigen was not identified in the brain, viral protein was detected in the gonads and adrenal glands of adult males. Males with more severe wounds had higher testosterone concentrations than males with no or low-grade wounds. Because wounding, testosterone, and virus shedding are associated among males, aggression may be the primary mode of Seoul virus transmission among male, but not female, Norway rats.  (+info)

Social status does not predict responses to Seoul virus infection or reproductive success among male Norway rats. (4/27)

Trade-offs exist among life history strategies that are used to increase survival and reproduction; such that, males that engage in more competitive behaviors may be more susceptible to infection. Hantaviruses are transmitted horizontally between rodents through the passage of virus in saliva during wounding and male rodents are more likely to be infected with hantaviruses than females. To determine whether a trade-off exists between dominance and susceptibility to Seoul virus infection, male Long Evans rats were group housed (3/cage) with a female rat and aggressive and subordinate behaviors were monitored during a 10 day group housing condition. After behavioral testing, males were individually housed, inoculated with Seoul virus, and blood, saliva, and fecal samples were collected. Dominant males initiated more aggressive encounters than subordinate males. Dominant and subordinate males, however, had similar steroid hormone concentrations, anti-Seoul virus IgG responses, and weight gain over the course of infection. A similar proportion of dominant and subordinate males shed virus in saliva and feces during infection. Using microsatellite DNA markers paternity was assigned to pups derived during the group housing period. In contrast to our initial hypothesis, dominant and subordinate males sired a similar percentage of pups. Taken together, host social status may not predict reproductive success or susceptibility to hantaviruses in rodent reservoir populations.  (+info)

Envelope glycoproteins of hantavirus can mediate cell-cell fusion independently. (5/27)

Hantaviruses (HTVs) are enveloped viruses and can induce low PH-dependent cell fusion. In this report we molecularly cloned viral glycoproteins (GPs) cDNA and nucleocapsid (NP) cDNA of two strains of Hantaan virus and one strain of Seoul virus and expressed in Vero E6 cells under control of a CMV promoter. The examinations of viral gene expressions were carried out by IFA and immune-precipitation. After treatment with low PH (PH 5.8) medium the syncytium were observed in the cells transfected with the GPs clones while in the cells transfected with the NP clones we did not find this phenomenon. Furthermore cotransfection of the NP and GPs did not enhance fusion activity. Treatment with anti-GP monoclonal antibodies could inhibit fusion activity whereas the antibodies against NP could not. These results indicated that GPs can mediate cell-cell fusion independently.  (+info)

Elevated testosterone and reduced 5-HIAA concentrations are associated with wounding and hantavirus infection in male Norway rats. (6/27)

Among rodents that carry hantaviruses, males are more likely to engage in aggression and to be infected than females. One mode of hantavirus transmission is via the passage of virus in saliva during wounding. The extent to which hantaviruses cause physiological changes in their rodent host that increase aggression and, therefore, virus transmission has not been fully documented. To assess whether steroid hormones and neurotransmitters contribute to the correlation between aggression and Seoul virus infection, Norway rats were trapped in Baltimore, Maryland and wounding, infection status, steroid hormones, and concentrations of neurotransmitters, including norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenol acetic acid (DOPAC), serotonin (5-HT), and 5-hydroxyindole-3-acetic acid (5-HIAA) in select brain regions were examined. Older males and males with high-grade wounds were more likely to have anti-Seoul virus IgG and viral RNA in organs than either juveniles or adult males with less severe wounds. Wounded males had higher circulating testosterone, lower hypothalamic 5-HIAA, and lower NE in the amygdala than males with no wounds. Infected males had higher concentrations of testosterone, corticosterone, NE in the hypothalamus, and DOPAC in the amygdala than uninfected males, regardless of wounding status. In the present study, wounded males that were infected with Seoul virus had elevated testosterone and reduced 5-HIAA concentrations, suggesting that these neuroendocrine mechanisms may contribute to aggression and the likelihood of transmission of hantavirus in natural populations of male Norway rats.  (+info)

Regulatory T cells enhance persistence of the zoonotic pathogen Seoul virus in its reservoir host. (7/27)

Hantaviruses are zoonotic pathogens that maintain a persistent infection in their reservoir hosts, yet the mechanisms mediating persistence remain unknown. Regulatory T cell responses cause persistent infection by suppressing proinflammatory and effector T cell activity; hantaviruses may exploit these responses to cause persistence. To test this hypothesis, male Norway rats were inoculated with Seoul virus and regulatory T cells were monitored during infection. Increased numbers of CD4(+)CD25(+)Forkhead box P3(+) T cells and expression of Forkhead box P3 and TGF-beta were observed in the lungs of male rats during persistent Seoul virus infection. To determine whether regulatory T cells modulate Seoul virus persistence, regulatory T cells were inactivated in male rats by using an anti-rat CD25 monoclonal antibody (NDS-63). Inactivation of regulatory T cells reduced the amount of Seoul virus RNA present in the lungs and the proportion of animals shedding viral RNA in saliva. Because regulatory T cells suppress proinflammatory-induced pathogenesis, pathologic observations in the lungs were evaluated during infection. Subclinical acute multifocal areas of hemorrhage and edema were noted in the lungs during infection; inactivation of regulatory T cells reduced the amount of pathologic foci. Expression of TNF was suppressed during the persistent phase of infection; inactivation of regulatory T cells eliminated the suppression of TNF. Taken together, these data suggest that regulatory T cells mediate Seoul virus persistence, possibly through elevated transcription and synthesis of TGF-beta and suppression of TNF. These data provide evidence of regulatory T cell involvement in the persistence of a zoonotic pathogen in its natural reservoir host.  (+info)

Sex differences in the recognition of and innate antiviral responses to Seoul virus in Norway rats. (8/27)

Among rodents that carry hantaviruses, more males are infected than females. Male rats also have elevated copies of Seoul virus RNA and reduced transcription of immune-related genes in the lungs than females. To further characterize sex differences in antiviral defenses and whether these differences are mediated by gonadal hormones, we examined viral RNA in the lungs, virus shedding in saliva, and antiviral defenses among male and female rats that were intact, gonadectomized neonatally, or gonadectomized in adulthood. Following inoculation with Seoul virus, high amounts viral RNA persisted longer in lungs from intact males than intact females. Removal of the gonads in males reduced the amount of viral RNA to levels comparable with intact females at 40 days post-inoculation (p.i.). Intact males shed more virus in saliva than intact females 15 days p.i.; removal of the gonads during either the neonatal period or in adulthood increased virus shedding in females and decreased virus shedding in males. Induction of pattern recognition receptors (PRRs; Tlr7 and Rig-I), expression of antiviral genes (Myd88, Visa, Jun, Irf7, Ifnbeta, Ifnar1, Jak2, Stat3, and Mx2), and production of Mx protein was elevated in the lungs of intact females compared with intact males. Gonadectomy had more robust effects on the induction of PRRs than on downstream IFNbeta or Mx2 expression. Putative androgen and estrogen response elements are present in the promoters of several of these antiviral genes, suggesting the propensity for sex steroids to directly affect dimorphic antiviral responses against Seoul virus infection.  (+info)