Serosurvey on Sheep Unravel Circulation of Rift Valley Fever Virus in Nigeria

Rift Valley fever is an arboviral zoonoses causing severe morbidity and mortality among humans and animals in many African countries. A cross-sectional study in populations of sheep reared around the Gidan-Waya Forest Reserve located in Jema'a LGA of Kaduna State, Nigeria to determine the serological evidence of exposure to Rift Valley fever virus (RVFV) using a commercial competitive enzyme-linked immunosorbent assay. Of the 200 sheep sampled, 9 (4.5%; 95 CI 2.23-8.33) were positive for antibodies to the RVFV. The detection of antibodies suggests a covert circulation among the sheep and may be indicative of a subclinical infection.

Virus envelope tissue factor promotes infection in mice

Essentials The coagulation initiator, tissue factor (TF), is on the herpes simplex virus 1 (HSV1) surface. HSV1 surface TF was examined in mice as an antiviral target since it enhances infection in vitro. HSV1 surface TF facilitated infection of all organs evaluated and anticoagulants were antiviral. Protease activated receptor 2 inhibited infection in vivo and its pre-activation was antiviral. SUMMARY: Background Tissue factor (TF) is the essential cell surface initiator of coagulation, and mediates cell signaling through protease-activated receptor (PAR) 2. Having a diverse cellular distribution, TF is involved in many biological pathways and pathologies. Our earlier work identified host cell-derived TF on the envelope covering several viruses, and showed its involvement in enhanced cell infection in vitro. Objective In the current study, we evaluated the in vivo effects of virus surface TF on infection and on the related modulator of infection PAR2. Methods With the use of herpes simplex virus type 1 (HSV1) as a model enveloped virus, purified HSV1 was generated with or without envelope TF through propagation in a TF-inducible cell line. Infection was studied after intravenous inoculation of BALB/c, C57BL/6J or C57BL/6J PAR2 knockout mice with 5 × 105 plaque-forming units of HSV1, mimicking viremia. Three days after inoculation, organs were processed, and virus was quantified with plaque-forming assays and quantitative real-time PCR. Results Infection of brain, lung, heart, spinal cord and liver by HSV1 required viral TF. Demonstrating promise as a therapeutic target, virus-specific anti-TF mAbs or small-molecule inhibitors of coagulation inhibited infection. PAR2 modulates HSV1 in vivo as demonstrated with PAR2 knockout mice and PAR2 agonist peptide. Conclusion TF is a constituent of many permissive host cell types. Therefore, the results presented here may explain why many viruses are correlated with hemostatic abnormalities, and indicate that TF is a novel pan-specific envelope antiviral target.

Dengue virus persists and replicates during storage of platelet and red blood cell units

BACKGROUND

Dengue virus (DENV) is a transfusion-transmissible arbovirus that threatens blood donor systems with approximately 200 million high-titer asymptomatic infections occurring annually. Here we investigated the viability of DENV during storage of donor-derived platelet (PLT) and red blood cell (RBC) units. While purified PLTs have been shown to generate viable DENV, RBCs are replication incompetent. Combined with different storage criteria, distinct virus persistence profiles were anticipated in PLT and RBC units.

STUDY DESIGN AND METHODS

Mimicking the virus titer of asymptomatic donors, purified DENV was spiked (10(5) -10(6) infectious units/mL) into PLT or RBC units produced and stored according to blood bank operating procedures. DENV was measured by infectious plaque-forming assays and by quantitative reverse transcription-polymerase chain reaction.

RESULTS

In both PLT (7 days, 20-24°C) and RBC (42 days, 1-6°C) units, infectious DENV persisted throughout storage despite logarithmic decay. In buffer alone, DENV infectivity was insignificant by Day 1 at 20 to 24°C or 14 days at 1 to 6°C. Infectious virus production was identified in stored PLT units using a translation inhibitor and supported by virus genome replication. Surprisingly, DENV was also produced in RBC units, implying the involvement of cells other than RBCs.

CONCLUSION

Both virus propagation and effects independent of cell function mitigate the intrinsic lability of DENV. Nevertheless, the overall rapid storage decay suggests that aged PLT and RBC units may be safer. These data raise awareness to the possible persistence of other conceivably more robust RNA viruses during the storage of cellular blood products.