Development of a luminex-based assay for the detection of anti-capripoxvirus and rift valley fever virus antibodies in domestic ruminants.

The three members of the genus capripoxvirus (CaPV), lumpy skin disease virus (LSDV), sheeppox virus (SPPV), and goatpox virus (GTPV) have common hosts and areas of overlapping geographical distribution with Rift Valley fever virus (RVFV). Hence, to ensure more cost-effective disease surveillance we developed and evaluated a Luminex assay for the simultaneous detection of antibodies against CaPV and RVFV in domestic ruminants. In cattle, the assay had a sensitivity (Se) of 98.

Attempted Transmission of Marburg Virus by Bat-Associated Fleas (Ischnopsyllidae: Thaumapsyllinae) to the Egyptian Rousette Bat ().

Egyptian rousette bats (ERBs) are implicated as reservoir hosts for Marburg virus (MARV), but natural mechanisms involved in maintenance of MARV in ERB populations remain undefined. A number of hematophagous ectoparasites, including fleas, parasitize bats. Subcutaneous (SC) inoculation of ERBs with MARV consistently results in viremia, suggesting that infectious MARV could be ingested by blood-sucking ectoparasites during feeding.

Epidemiological and Genomic Characterisation of Middelburg and Sindbis Alphaviruses Identified in Horses with Febrile and Neurological Infections, South Africa (2014-2018).

Although Old World alphaviruses, Middelburg- (MIDV) and Sindbis virus (SINV), have previously been detected in horses and wildlife with neurologic disease in South Africa, the pathogenesis and clinical presentation of MIDV and SINV infections in animals are not well documented. Clinical samples from horses across South Africa with acute or fatal neurologic and febrile infections submitted between 2014-2018 were investigated. In total, 69/1084 (6.

At Least Three Doses of Leading Vaccines Essential for Neutralisation of SARS-CoV-2 Omicron Variant.

Plasma samples taken at different time points from donors who received either AstraZeneca (Vaxzevria) or Pfizer (Comirnaty) or Moderna (Spikevax) coronavirus disease-19 (COVID-19) vaccine were assessed in virus neutralization assays against Delta and Omicron variants of concern and a reference isolate (VIC31). With the Pfizer vaccine there was 6-8-fold reduction in 50% neutralizing antibody titres (NT) against Delta and VIC31 at 6 months compared to 2 weeks after the second dose; followed by 25-fold increase at 2 weeks after the third dose. Neutralisation of Omicron was only consistently observed 2 weeks after the third dose, with most samples having titres below the limit of detection at earlier timepoints.

Chemical inactivation of foot-and-mouth disease virus in bovine tongue epithelium for safe transport and downstream processing.

Epithelial tissue or vesicular fluid from an unruptured or recently ruptured vesicle is the sample of choice for confirmatory laboratory diagnosis of foot-and-mouth disease (FMD). However, in 'FMD-free' countries the transport and downstream processing of such samples from potentially infected animals present a biosafety risk, particularly during heightened surveillance, potentially involving decentralised testing in laboratories without adequate biocontainment facilities. In such circumstances, rapid inactivation of virus, if present, prior to transport becomes a necessity, while still maintaining the integrity of diagnostic analytes.

Detection and genome characterization of Middelburg virus strains isolated from CSF and whole blood samples of humans with neurological manifestations in South Africa.

Background: The Old world Alphavirus, Middelburg virus (MIDV), is not well known and although a few cases associated with animal illness have previously been described from Southern Africa, there has been no investigation into the association of the virus with human illness. The current study aimed to investigate possible association of MIDV infection with febrile or neurological manifestations in hospitalized or symptomatic patients fromGauteng, South Africa.

Methods: This study is a descriptive retrospective and prospective laboratory based study.

A Stabilized, Monomeric, Receptor Binding Domain Elicits High-Titer Neutralizing Antibodies Against All SARS-CoV-2 Variants of Concern.

Saturation suppressor mutagenesis was used to generate thermostable mutants of the SARS-CoV-2 spike receptor-binding domain (RBD). A triple mutant with an increase in thermal melting temperature of ~7°C with respect to the wild-type B.1 RBD and was expressed in high yield in both mammalian cells and the microbial host, , was downselected for immunogenicity studies.

Vector Competence of (Diptera: Nycteribiidae) for Marburg Virus Transmission in (Chiroptera: Pteropodidae).

This study aimed to determine the vector competence of bat-associated nycteribiid flies () for Marburg virus (MARV) in the Egyptian Rousette Bat (ERB), . In flies fed on subcutaneously infected ERBs and tested from 3 to 43 days post infection (dpi), MARV was detected only in those that took blood during the peak of viremia, 5-7 dpi. Seroconversion did not occur in control bats in contact with MARV-infected bats infested with bat flies up to 43 days post exposure.

Rift Valley Fever Virus Seroprevalence among Humans, Northern KwaZulu-Natal Province, South Africa, 2018-2019.

We detected Rift Valley fever virus (RVFV) IgM and IgG in human serum samples collected during 2018-2019 in northern KwaZulu-Natal Province, South Africa. Our results show recent RVFV circulation and likely RVFV endemicity in this tropical coastal plain region of South Africa in the absence of apparent clinical disease.

Large-Scale International Validation of an Indirect ELISA Based on Recombinant Nucleocapsid Protein of Rift Valley Fever Virus for the Detection of IgG Antibody in Domestic Ruminants.

Diagnostic performance of an indirect enzyme-linked immunosorbent assay (I-ELISA) based on a recombinant nucleocapsid protein (rNP) of the Rift Valley fever virus (RVFV) was validated for the detection of the IgG antibody in sheep ( = 3367), goat ( = 2632), and cattle ( = 3819) sera. Validation data sets were dichotomized according to the results of a virus neutralization test in sera obtained from RVF-endemic (Burkina Faso, Democratic Republic of Congo, Mozambique, Senegal, Uganda, and Yemen) and RVF-free countries (France, Poland, and the USA). Cut-off values were defined using the two-graph receiver operating characteristic analysis.

A 1958 Isolate of Kedougou Virus (KEDV) from Ndumu, South Africa, Expands the Geographic and Temporal Range of KEDV in Africa.

The mosquito-borne flavivirus, Kedougou virus (KEDV), first isolated in Senegal in 1972, is genetically related to dengue, Zika (ZIKV) and Spondweni viruses (SPOV). Serological surveillance studies in Senegal and isolation of KEDV in the Central African Republic indicate occurrence of KEDV infections in humans, but to date, no disease has been reported. Here, we assembled the coding-complete genome of a 1958 isolate of KEDV from a pool of mosquitoes collected in Ndumu, KwaZulu-Natal, South Africa.

Immunogenicity and Protective Efficacy of a Highly Thermotolerant, Trimeric SARS-CoV-2 Receptor Binding Domain Derivative.

The receptor binding domain (RBD) of SARS-CoV-2 is the primary target of neutralizing antibodies. We designed a trimeric, highly thermotolerant glycan engineered RBD by fusion to a heterologous, poorly immunogenic disulfide linked trimerization domain derived from cartilage matrix protein. The protein expressed at a yield of ∼80-100 mg/L in transiently transfected Expi293 cells, as well as CHO and HEK293 stable cell lines and formed homogeneous disulfide-linked trimers.

Lithium inhibits NF-κB nuclear translocation and modulate inflammation profiles in Rift valley fever virus-infected Raw 264.7 macrophages.

Introduction: Rift Valley fever virus (RVFV) is a zoonotic life-threatening viral infection endemic across sub-Saharan African countries and the Arabian Peninsula; however, there is a growing panic of its spread to non-endemic regions. This viral infection triggers a wide spectrum of symptoms that span from fibril illnesses to more severe symptoms such as haemorrhagic fever and encephalitis. These severe symptoms have been associated with dysregulated immune response propagated by the virulence factor, non-structural protein (NSs).

ChAdOx1 nCoV-19 (AZD1222) vaccine candidate significantly reduces SARS-CoV-2 shedding in ferrets.

Vaccines against SARS-CoV-2 are likely to be critical in the management of the ongoing pandemic. A number of candidates are in Phase III human clinical trials, including ChAdOx1 nCoV-19 (AZD1222), a replication-deficient chimpanzee adenovirus-vectored vaccine candidate. In preclinical trials, the efficacy of ChAdOx1 nCoV-19 against SARS-CoV-2 challenge was evaluated in a ferret model of infection.

ILRUN Downregulates ACE2 Expression and Blocks Infection of Human Cells by SARS-CoV-2.

The human protein-coding gene (inflammation and lipid regulator with UBA-like and NBR1-like domains; previously C6orf106) was identified as a proviral factor for Hendra virus infection and was recently characterized to function as an inhibitor of type I interferon expression. Here, we have utilized transcriptome sequencing (RNA-seq) to define cellular pathways regulated by ILRUN in the context of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection of Caco-2 cells. We find that inhibition of ILRUN expression by RNA interference alters transcription profiles of numerous cellular pathways, including upregulation of the SARS-CoV-2 entry receptor and several other members of the renin-angiotensin aldosterone system.

Ribosome-Profiling Reveals Restricted Post Transcriptional Expression of Antiviral Cytokines and Transcription Factors during SARS-CoV-2 Infection.

The global COVID-19 pandemic caused by SARS-CoV-2 has resulted in over 2.2 million deaths. Disease outcomes range from asymptomatic to severe with, so far, minimal genotypic change to the virus so understanding the host response is paramount.

Epidemiology and Genomic Analysis of Equine Encephalosis Virus Detected in Horses with Clinical Signs in South Africa, 2010-2017.

Equine encephalosis virus (EEV) is a neglected virus endemic to South Africa and is considered to generally result in mild disease in equines. Specimens were analyzed from live horses that presented with undefined neurological, febrile, or respiratory signs, or sudden and unexpected death. Between 2010 and 2017, 111 of 1523 (7.

Shedding of Marburg Virus in Naturally Infected Egyptian Rousette Bats, South Africa, 2017.

We detected Marburg virus RNA in rectal swab samples from Egyptian rousette bats in South Africa in 2017. This finding signifies that fecal contamination of natural bat habitats is a potential source of infection for humans. Identified genetic sequences are closely related to Ravn virus, implying wider distribution of Marburg virus in Africa.

Concentration of infectious SARS-CoV-2 by polyethylene glycol precipitation.

The development of medical countermeasures against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires robust viral assays. Here we have adapted a protocol for polyethylene glycol (PEG)-mediated precipitation of SARS-CoV-2 stocks without the need for ultracentrifugation. Virus precipitation resulted in a ∼1.

Patterns of Rift Valley fever virus seropositivity in domestic ruminants in central South Africa four years after a large outbreak.

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis showing complex epidemiological patterns that are poorly understood in South Africa. Large outbreaks occur in the central interior at long, irregular intervals, most recently in 2010-2011; however, the level of herd immunity of ruminant livestock, a key determinant of outbreaks, is unknown. During 2015-2016 a cross-sectional study on 234 randomly-selected farms investigated the prevalence, patterns of, and factors associated with, antibodies to RVF virus (RVFV) in livestock in an area heavily affected by that outbreak.

Development and validation of a pen side test for Rift Valley fever.

Background: Rift Valley fever (RVF) is one of the main vector borne zoonotic diseases that affects a wide range of ruminants and human beings in Africa and the Arabian Peninsula. A rapid and specific test for RVF diagnosis at the site of a suspected outbreak is crucial for the implementation of control measures.

Methodology/principal Findings: A first-line lateral flow immunochromatographic strip test (LFT) was developed for the detection of the nucleoprotein (N) of the RVF virus (RVFV).