Neutralizing antibodies against Rift Valley fever virus in wild antelope in far northern KwaZulu‐Natal, South Africa, indicate recent virus circulation

In vitro neutralizing antibodies have been often correlated with protection against Rift Valley fever virus (RVFV) infection. We have reported previously that a single inoculation of sucrose-purified modified vaccinia Ankara (MVA) encoding RVFV glycoproteins (rMVAGnGc) was sufficient to induce a protective immune response in mice after a lethal RVFV challenge. Protection was related to the presence of glycoprotein specific CD8+ cells, with a low-level detection of in vitro neutralizing antibodies. In this work we extended those observations aimed to explore the role of humoral responses after MVA vaccination and to study the contribution of each glycoprotein antigen to the protective efficacy. Thus, we tested the efficacy and immune responses in BALB/c mice of recombinant MVA viruses expressing either glycoprotein Gn (rMVAGn) or Gc (rMVAGc). In the absence of serum neutralizing antibodies, our data strongly suggest that protection of vaccinated mice upon the RVFV challenge can be achieved by the activation of cellular responses mainly directed against Gc epitopes. The involvement of cellular immunity was stressed by the fact that protection of mice was strain dependent. Furthermore, our data suggest that the rMVA based single dose vaccination elicits suboptimal humoral immune responses against Gn antigen since disease in mice was exacerbated upon virus challenge in the presence of rMVAGnGc or rMVAGn immune serum. Thus, Gc-specific cellular immunity could be an important component in the protection after the challenge observed in BALB/c mice, contributing to the elimination of infected cells reducing morbidity and mortality and counteracting the deleterious effect of a subneutralizing antibody immune response.

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Panveld oviposition sites of floodwater Aedes mosquitoes and attempts to detect transovarial transmission of Rift Valley fever virus in South Africa

Medical and Veterinary Entomology ◽

10.1111/j.1365-2915.1988.tb00189.x ◽

1988 ◽

Vol 2 (3) ◽

pp. 231-236 ◽

Cited By ~ 14

Author(s):

THOMAS P. GARGAN ◽

PETER G. JUPP ◽

ROBERT J. NOVAK

Keyword(s):

South Africa ◽

Rift Valley ◽

Rift Valley Fever ◽

Rift Valley Fever Virus ◽

Fever Virus ◽

Transovarial Transmission ◽

Valley Fever ◽

Aedes Mosquitoes ◽

Oviposition Sites

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Detection of Rift Valley Fever Virus Lineage H from South Africa through Syndromic Sentinel Surveillance Network in Senegal

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab655 ◽

2021 ◽

Author(s):

Ndeye Sakha Bob ◽

Mamadou Aliou Barry ◽

Moussa Moise Diagne ◽

Martin Faye ◽

Marie Henriette Dior Ndione ◽

...

Keyword(s):

South Africa ◽

Rift Valley ◽

Surveillance System ◽

Rift Valley Fever ◽

Rift Valley Fever Virus ◽

Fever Virus ◽

Enzyme Linked Immunosorbent Assay ◽

Rt Pcr ◽

Surveillance Network ◽

Valley Fever

Abstract Background Rift Valley fever virus (RVFV) is an arbovirus that causes epizootics and epidemics among livestock population and humans. Our surveillance system has revealed multiple emergences and re-emergences of RVFV in West Africa over the last decade. Methods In Senegal a sentinel syndromic surveillance network (4S) has been implemented since 2011. Samples from human suspected arbovirus infection in 4S sentinel sites were sent to Institut Pasteur de Dakar (IPD) where arbovirus diagnosis by enzyme-linked immunosorbent assay (ELISA), real-time reverse transcription polymerase chain reaction (RT-PCR), and virus isolation were performed. Overall, IPD has received a total of 1,149 samples from arboviral suspected patients through the 4S network from January to December 2020. These samples were screened for seven arboviruses including RVFV. Whole genome sequencing of positive RVFV samples by RT-PCR were performed using Illumina Miseq platform followed by genome assembly. Phylogenetic analysis were performed using MEGA X. Results Out of the 1,149 arbovirus suspected cases, four RVFV positive samples were detected with RT-PCR while five RVFV positive samples were detected by ELISA. Complete genome sequences were obtained for three strains among the four positive samples by RT-PCR. Phylogenetic analyses indicated an emergence of a virus first described in South Africa during a major outbreak. Conclusion Strong surveillance system allowed the detection of RVFV outbreak in Senegal in 2020. The obtained genomes clustered with strains from South Africa belonging to lineage H. This calls for an implementation of a strong surveillance system in wild animals, humans, and livestock simultaneously in all African Countrries.

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Transmission Potential of Rift Valley Fever Virus over the Course of the 2010 Epidemic in South Africa

Emerging Infectious Diseases ◽

10.3201/eid1906.121641 ◽

2013 ◽

Vol 19 (6) ◽

pp. 916-924 ◽

Cited By ~ 17

Author(s):

Raphaëlle Métras ◽

Marc Baguelin ◽

W. John Edmunds ◽

Peter N. Thompson ◽

Alan Kemp ◽

...

Keyword(s):

South Africa ◽

Rift Valley ◽

Rift Valley Fever ◽

Rift Valley Fever Virus ◽

Fever Virus ◽

Valley Fever ◽

Transmission Potential

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

Scientific Reports ◽

10.1038/s41598-020-62453-6 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Yusuf B. Ngoshe ◽

Alida Avenant ◽

Melinda K. Rostal ◽

William B. Karesh ◽

Janusz T. Paweska ◽

...

Keyword(s):

South Africa ◽

Rift Valley ◽

Rift Valley Fever ◽

Rift Valley Fever Virus ◽

Fever Virus ◽

Valley Fever ◽

Domestic Ruminants ◽

Large Outbreak ◽

Central South

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Genetically Modified Rabies Virus Vector-Based Rift Valley Fever Virus Vaccine is Safe and Induces Efficacious Immune Responses in Mice

Viruses ◽

10.3390/v11100919 ◽

2019 ◽

Vol 11 (10) ◽

pp. 919 ◽

Cited By ~ 3

Author(s):

Zhang ◽

Hao ◽

Feng ◽

Jin ◽

Yan ◽

...

Keyword(s):

T Cells ◽

Rabies Virus ◽

Rift Valley ◽

Neutralizing Antibodies ◽

Rift Valley Fever ◽

Memory T Cells ◽

Rift Valley Fever Virus ◽

Fever Virus ◽

Igg Antibodies ◽

Valley Fever

Rift Valley fever virus (RVFV), which causes Rift Valley fever (RVF), is a mosquito-borne zoonotic pathogen that causes serious morbidity and mortality in livestock and humans. RVF is a World Health Organization (WHO) priority disease and, together with rabies, is a major health burden in Africa. Here, we present the development and characterization of an inactivated recombinant RVFV and rabies virus (RABV) vaccine candidate (rSRV9-eGn). Immunization with rSRV9-eGn stimulated the production of RVFV-specific IgG antibodies and induced humoral and cellular immunity in mice but did not induce the production of neutralizing antibodies. IgG1 and IgG2a were the main isotypes observed by IgG subtype detection, and IgG3 antibodies were not detected. The ratios of IgG1/IgG2a > 1 indicated a Type 2 humoral immune response. An effective vaccine is intended to establish a long-lived population of memory T cells, and mice generated memory cells among the proliferating T cell population after immunization with rSRV9-eGn, with effector memory T cells (TEM) as the major population. Due to the lack of prophylactic treatment experiments, it is impossible to predict whether this vaccine can protect animals from RVFV infection with only high titres of anti-RVFV IgG antibodies and no neutralizing antibodies induced, and thus, protection confirmation needs further verification. However, this RVFV vaccine designed with RABV as the vector provides ideas for the development of vaccines that prevent RVFV and RABV infections.

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