Divergent Rhabdovirus Discovered in a Patient with New-Onset Nodding Syndrome

A divergent rhabdovirus was discovered in the bloodstream of a 15-year-old girl with Nodding syndrome from Mundri West County in South Sudan. Nodding syndrome is a progressive degenerative neuropathy of unknown cause affecting thousands of individuals in Sub-Saharan Africa. The index case was previously healthy until she developed head-nodding seizures four months prior to presentation. Virus discovery by VIDISCA-NGS on the patient’s plasma detected multiple sequence reads belonging to a divergent rhabdovirus. The viral load was 3.85 × 10³ copies/mL in the patient’s plasma and undetectable in her cerebrospinal fluid. Further genome walking allowed for the characterization of full coding sequences of all the viral proteins (N, P, M, U1, U2, G, U3, and L). We tentatively named the virus “Mundri virus” (MUNV) and classified it as a novel virus species based on the high divergence from other known viruses (all proteins had less than 43% amino acid identity). Phylogenetic analysis revealed that MUNV forms a monophyletic clade with several human-infecting tibroviruses prevalent in Central Africa. A bioinformatic machine-learning algorithm predicted MUNV to be an arbovirus (bagged prediction strength (BPS) of 0.9) transmitted by midges (BPS 0.4) with an artiodactyl host reservoir (BPS 0.9). An association between MUNV infection and Nodding syndrome was evaluated in a case–control study of 72 patients with Nodding syndrome (including the index case) matched to 65 healthy households and 48 community controls. No subject, besides the index case, was positive for MUNV RNA in their plasma. A serological assay detecting MUNV anti-nucleocapsid found, respectively, in 28%, 22%, and 16% of cases, household controls and community controls to be seropositive with no significant differences between cases and either control group. This suggests that MUNV commonly infects children in South Sudan yet may not be causally associated with Nodding syndrome.

Cytokine production by human leukocytes with different expressions of natural antiviral immunity and the effect of antibodies against interferons and TNF-alpha

Introduction:

Two activities of innate antiviral immunity were studied: the resistance of human peripheral blood mononuclear cells (PMBCs) ex vivo to viral infection and the production of cytokines.

Materials and Methods:

Samples of blood were taken from healthy blood donors and from persons with frequent infections of the upper respiratory system. PMBCs were isolated by gradient centrifugation. Vesicular stomatitis virus (VSV) was used as the indicatory virus to infect PMBCs. The cytokines: IFN, TNF, and IL-6 were titrated by biological methods and IL-10 by ELISA.

Results:

Blood donors were divided for two groups: those with VSV-resistant and those with VSV-sensitive PMBCs and secretion of cytokines by them was compared. The resistant PMBCs produced more cytokines than the sensitive ones. A statistically significant difference, was found only in the case of the IFNs. To examine the contribution of IFNs and TNF in maintaining resistance, leukocytes from both groups were treated with specific anti-cytokine antibodies. The authors’ previous study showed that the elimination of spontaneous IFN-±, IFN-β, IFN-γ, and TNF-± from resistant leukocytes resulted in increased VSV replication This indicates the important role of cytokines. In VSV-sensitive PMBCs, anti-IFN-± showed the opposite effect (decreased virus replication). In the absence of spontaneous IFN-±, disturbances in cytokine production were observed.

Conclusions:

Complete resistance of PMBC to VSV infection is accompanied by higher cytokine release, The paradoxical effect of anti-IFN-± on virus replication in leukocytes sensitive to viral infection may be attributed to changes in the cytokine profile balance, i.e. high TNF production by VSV-infected leukocytes and a complete reduction of IL-6 production.

Transmission of vesicular stomatitis New Jersey virus to cattle by the biting midge Culicoides sonorensis (Diptera: Ceratopogonidae)

Laboratory-reared Culicoides sonorensis Wirth & Jones were infected with vesicular stomatitis virus serotype New Jersey (family Rhabdoviridae, genus Vesiculovirus, VSNJV) through intrathoracic inoculation. After 10-d incubation at 25 degrees C, these insects were allowed to blood feed on four steers. Two other steers were exposed to VSNJV through intralingual inoculation with 10(8) tissue culture infective dose50 VSNJV. All six steers became seropositive for VSNJV. The results demonstrate the ability of C. sonorensis to transmit VSNJV to livestock. Only the animals intralingually inoculated with VSNJV showed clinical signs in the form of vesicles at the site of inoculation. Uninfected C. sonorensis allowed to feed on the exposed animals did not become infected with VSNJV. Animals infected by C. sonorensis showed a slower antibody response compared with intralingually inoculated animals. This is probably because of different amounts of virus received via insect transmission and syringe inoculation. A significant difference was found in the serum acute-phase protein alpha-1-acid glycoprotein in animals that received VSNJV through C. sonorensis transmission. These animals had previously been exposed to insect attack in the field compared with intralingually inoculated animals and C. sonorensis-infected animals that had been protected from insect attack. The failure to observe clinical signs of vesicular stomatitis through transmission of VSNJV by C. sonorensis may explain widespread subclinical infections during vesicular stomatitis epidemics.

Pre-exposure rabies booster vaccinations: a literature review

In Europe, more attention is turning towards human infection with European bat lyssaviruses (EBLVs). Following the death of a bat conservationist from EBLV in Scotland, in 2002, the Department of Health in the United Kingdom (UK) recommended that all bat workers receive prophylactic rabies vaccination. This systematic literature review aims to review the evidence base for current UK policy on rabies booster vaccination. Ten papers met the inclusion criteria and were reviewed. Most of the papers were prospective cohort studies with follow-up ending after the first booster vaccination. One year after a three dose intramuscular primary rabies vaccination course, 87.9-100 % of participants had a rabies antibody level > or = 0.5 IU/ml, before the first booster. It may, therefore, be prudent for the UK to reduce its current recommended interval, primary course to first booster, from two years to one year. More research, with longer follow-up, is required to enable recommendations on subsequent boosters to be made.

EBLV-2 prevalence in the United Kingdom as determined by surveillance testing

Five cases of EBLV-2 have been detected in the UK since 1996, with all wildlife cases in the Daubenton's bat: one on the south coast in Sussex in 1996, one in Lancashire in 2002, another in 2003, one in Surrey in 2004 and a human fatality in Angus, Scotland, in 2002. As a result of the human case, a seroprevalence study, aimed primarily at the Daubenton's bat was conducted in 2003 in Scotland and at some sites in England. In Scotland, 198 Daubenton's, 20 Natterer's and 6 pipistrelles were caught at 19 sites and analysed, while in England 67 Daubenton, 2 Brandts/ Whiskered and 4 pipistrelle bats were analysed from four sites in Lancashire. Analysis of blood was performed by a modified fluorescent antibody virus neutralisation test (mFAVN) to determine antibody titre to EBLV-2. Ignoring those sites where we had a priori reason to expect infected bats, the overall seroprevalence was between 0.7-5.1 % (95 % confidence interval), with a maximum likelihood estimate of 2.2 %. Mouth swabs were taken and tested for virus genome by RT-PCR and live virus by tissue culture isolation. All of the PCR and isolation results were negative suggesting that none of the bats sampled were actively excreting virus. This suggests a low level of active infection in Britain and raises the possibility that bats may recover following exposure to EBLV-2.

Cytokine levels in Chandipura virus associated encephalopathy in children

An association of Chandipura (CHP) virus with an explosive outbreak of encephalitis in children from India affecting 349 children with 55% mortality was recently reported. To understand the role of cytokines in the pathogenesis of CHP infection, 14 paediatric encephalitis cases admitted to a tertiary care hospital and 5 age-matched apparently healthy control children were studied. At the time of sampling, post onset of disease was < or =2 d (Group A, n = 4) and >2 d (Group B, n = 10). Concentrations of IL-2, IFN-gamma, TNF-alpha and IL-6 in mitogen stimulated PBMC supernatants of patients and controls were assessed by ELISA. IL-2 levels in Group A and B were significantly higher compared with controls (28.4+/-21.9 vs <7.8, p=0.01, 269.4+/-311.0.vs <7.8, p = 0.01). IFN-gamma levels were significantly elevated in both the groups compared with controls (394.4+/-107.7 vs 13.9+/-20.9, p = 0.01, 339.5+/-244.9 vs 13.9+/-20.9, p = 0.01). TNF-alpha and IL-6 levels were significantly higher in Group B compared with controls (573.1+/-472.5 vs 113.4.+/-148.3, p = 0.01, 486.2+/-145.7 vs 113.8+/-82.4, p = 0.003). Cytokine levels were not significantly different in Groups A and B.

Impact of macrophage and dendritic cell subset elimination on antiviral immunity, viral clearance and production of type 1 interferon

We report herein that vesicular stomatitis virus (VSV) induced a concurrent primary Th1 (T helper 1) and Th2 cytokine response detectable ex vivo. Liposome-encapsulated clodronate-mediated elimination of CD8- marginal dendritic cells (DCs) and splenic macrophages (m Phi), but not CD8+ interdigitating DCs, prior to infection resulted in a markedly diminished chemokine and Th1 (IL-2, interferon-gamma) cytokine response, although the Th2 response (IL-4) remained relatively intact. Repopulation with marginal DCs and marginal metallophilic macrophages (MMM) restored Th1 cytokine profiles but did not restore chemokine responsiveness or reduce VSV-induced morbidity/mortality. Chemokine competency returned approximately 4 weeks post-depletion, which correlated temporally with repopulation of the spleen with marginal zone macrophages (MZM) and red pulp macrophages (RPM). Unexpectedly, virus-induced morbidity persisted for over 1 month post-depletion and was associated with virus dissemination and distinctive histological lesions in the liver. Depletion of interferon-producing plasmacytoid dendritic cells did not account for virus-induced morbidity because serum levels of type I interferon were not diminished in Cl2MBP-liposome-treated mice. Thus, distinct m Phi subsets are critical for chemokine production and viral clearance, and, in their absence, VSV disseminates even in the presence of high titers of interferon.

CCR2+ and CCR5+ CD8+ T cells increase during viral infection and migrate to sites of infection

Chemokines and their receptors play a critical role in the selective recruitment of various leukocyte subsets. In this study, we correlated the expression of multiple chemokine and CC chemokine receptor (CCR) genes during the course of intracerebral (i.c.) infection with lymphocytic choriomeningitis virus (LCMV) and vesicular stomatitis virus (VSV), which are prototypic of a noncytopathic and a cytopathic virus, respectively. Infection of mice with either virus resulted in rapid activation and overlapping cerebral expression of a number of chemokine genes. Infection with VSV i.c. causes a rapidly lethal, T cell-independent encephalitis, and infection resulted in a dramatic early up-regulation of chemokine gene expression. Similar marked up-regulation of chemokine expression was not seen until late after LCMV infection and required the presence of activated T cells. Cerebral CCR gene expression was dominated by CCR1, CCR2 and CCR5. However, despite a stronger initial chemokine signal in VSV-infected mice, only LCMV-induced T cell-dependent inflammation was found to be associated with substantially increased expression of CCR genes. Virus-activated CD8+ T cells were found to express CCR2 and CCR5, whereas activated monocytes/macrophages expressed CCR1 in addition to CCR2 and CCR5. Together, these CCR profiles readily account for the CCR profile prominent during CD8+-dependent CNS inflammation.

A survey of expressed genes in the leukocytes of Japanese flounder, Paralichthys olivaceus, infected with Hirame rhabdovirus

We constructed a cDNA library of Japanese flounder, Paralichthys olivaceus, leukocytes that were infected with Hirame rhabdovirus (HRV) in order to analyze some of the genes that are induced and expressed by virus infection in the immune system. Four hundred and fifty-two partial sequences representing 300 cDNA clones were obtained from the 5' and/or 3' ends of inserts derived from the Japanese flounder leukocyte cDNA library. About three-quarters of the 300 cDNA clones (217 clones, 72.3%) represented known genes in the public databases, whereas the remaining 83 (27.7%) of the clones did not show any significant homology with the sequences in the public databases. Clones matching known genes were classified into 12 categories according to their function or distribution. Only 40 (18.4%) of the 217 known genes showed homology with fish genes deposited in the database. Thirty (10%) of the clones, encoding 21 different sequences, and representing several categories, were identified as putative biodefense genes or genes associated with the immune response. Nineteen of the 21 putative biodefense or immune response-related cDNAs have not been previously reported in fish genes or cDNAs.

Differential diagnosis of fish pathogenic rhabdoviruses by reverse transcriptase-dependent polymerase chain reaction

Reverse transcriptase-dependent polymerase chain reaction (RT-PCR) was applied to the detection and differentiation of viral hemorrhagic septicemia virus (VHSV) and infectious hematopoietic necrosis virus (IHNV) using primer pairs designed for the amplification of glycoprotein G-specific gene fragments of the two viruses. The products of 443 bp (VHS) and 548 bp (IHN), respectively, were amplified from the total RNA extracts of RTG-2 cells infected with a total of 9 different strains of either VHS virus or IHN virus. Restriction analysis using FokI, and DNA sequencing of the PCR products demonstrated specificity of the amplification. The RT-PCR amplification of VHSV or IHNV G-genes was found to be a simple, highly specific and sensitive method allowing differential diagnosis of VHS and IHN within 8 h.