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Gerken KN, Owuor KO, Ndenga B, Wambua S, Winter C, Chemutai S, Omukuti R, Arabu D, Miring’u I, Wilson WC, Mutuku F, Waggoner JJ, Pinsky B, Bosire C, LaBeaud AD. Expanding Understanding of Urban Rift Valley Fever Risk and Associated Vector Ecology at Slaughterhouses in Kisumu, Kenya. Pathogens 2024; 13:488. [PMID: 38921786 PMCID: PMC11206928 DOI: 10.3390/pathogens13060488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/01/2024] [Accepted: 06/04/2024] [Indexed: 06/27/2024] Open
Abstract
Rift Valley fever virus (RVFV) is an adaptable arbovirus that can be transmitted by a wide variety of arthropods. Widespread urban transmission of RVFV has not yet occurred, but peri-urban outbreaks of RVFV have recently been documented in East Africa. We previously reported low-level exposure in urban communities and highlighted the risk of introduction via live animal influx. We deployed a slaughtered animal testing framework in response to an early warning system at two urban slaughterhouses and tested animals entering the meat value chain for anti-RVFV IgG and IgM antibodies. We simultaneously trapped mosquitoes for RVFV and bloodmeal testing. Out of 923 animals tested, an 8.5% IgG seroprevalence was identified but no evidence of recent livestock exposure was detected. Mosquito species abundance varied greatly by slaughterhouse site, which explained 52% of the variance in blood meals. We captured many Culex spp., a known RVFV amplifying vector, at one of the sites (p < 0.001), and this species had the most diverse blood meals. No mosquito pools tested positive for RVFV antigen using a rapid VecTOR test. These results expand understanding of potential RVF urban disease ecology, and highlight that slaughterhouses are key locations for future surveillance, modelling, and monitoring efforts.
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Affiliation(s)
- Keli Nicole Gerken
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA 94305, USA; (B.P.); (A.D.L.)
| | - Kevin Omondi Owuor
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu 40100, Kenya; (K.O.O.); (B.N.); (C.W.)
| | - Bryson Ndenga
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu 40100, Kenya; (K.O.O.); (B.N.); (C.W.)
| | - Sammy Wambua
- Pwani University Biosciences Research Centre (PUBReC), Pwani University, Kilifi 80108, Kenya; (S.W.); (S.C.); (R.O.); (D.A.); (I.M.)
- Research and Conservation Support Society (RECOURSE), Kilifi 80108, Kenya
- School of Biodiversity One Health and Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Christabel Winter
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu 40100, Kenya; (K.O.O.); (B.N.); (C.W.)
| | - Salome Chemutai
- Pwani University Biosciences Research Centre (PUBReC), Pwani University, Kilifi 80108, Kenya; (S.W.); (S.C.); (R.O.); (D.A.); (I.M.)
- Research and Conservation Support Society (RECOURSE), Kilifi 80108, Kenya
| | - Rodney Omukuti
- Pwani University Biosciences Research Centre (PUBReC), Pwani University, Kilifi 80108, Kenya; (S.W.); (S.C.); (R.O.); (D.A.); (I.M.)
- Research and Conservation Support Society (RECOURSE), Kilifi 80108, Kenya
| | - Daniel Arabu
- Pwani University Biosciences Research Centre (PUBReC), Pwani University, Kilifi 80108, Kenya; (S.W.); (S.C.); (R.O.); (D.A.); (I.M.)
- Research and Conservation Support Society (RECOURSE), Kilifi 80108, Kenya
| | - Irene Miring’u
- Pwani University Biosciences Research Centre (PUBReC), Pwani University, Kilifi 80108, Kenya; (S.W.); (S.C.); (R.O.); (D.A.); (I.M.)
- Research and Conservation Support Society (RECOURSE), Kilifi 80108, Kenya
| | - William C. Wilson
- Foreign Arthropod-Borne Animal Disease Research, United States Department of Agriculture-Agriculture Research Service (USDA-ARS), Manhattan, KS 66502, USA;
| | - Francis Mutuku
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa 80110, Kenya;
| | - Jesse J. Waggoner
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA;
| | - Benjamin Pinsky
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA 94305, USA; (B.P.); (A.D.L.)
| | - Carren Bosire
- Department of Pure and Applied Sciences, Technical University of Mombasa, Mombasa 80100, Kenya;
| | - Angelle Desiree LaBeaud
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA 94305, USA; (B.P.); (A.D.L.)
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Bron GM, Wichgers Schreur PJ, de Jong MCM, van Keulen L, Vloet RPM, Koenraadt CJM, Kortekaas J, ten Bosch QA. Quantifying Rift Valley fever virus transmission efficiency in a lamb-mosquito-lamb model. Front Cell Infect Microbiol 2023; 13:1206089. [PMID: 38170150 PMCID: PMC10759236 DOI: 10.3389/fcimb.2023.1206089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 10/30/2023] [Indexed: 01/05/2024] Open
Abstract
Rift Valley fever virus (RVFV) is a (re)emerging mosquito-borne pathogen impacting human and animal health. How RVFV spreads through a population depends on population-level and individual-level interactions between vector, host and pathogen. Here, we estimated the probability for RVFV to transmit to naive animals by experimentally exposing lambs to a bite of an infectious mosquito, and assessed if and how RVFV infection subsequently developed in the exposed animal. Aedes aegypti mosquitoes, previously infected via feeding on a viremic lamb, were used to expose naive lambs to the virus. Aedes aegypti colony mosquitoes were used as they are easy to maintain and readily feed in captivity. Other mosquito spp. could be examined with similar methodology. Lambs were exposed to either 1-3 (low exposure) or 7-9 (high exposure) infectious mosquitoes. All lambs in the high exposure group became viremic and showed characteristic signs of Rift Valley fever within 2-4 days post exposure. In contrast, 3 out of 12 lambs in the low exposure group developed viremia and disease, with similar peak-levels of viremia as the high exposure group but with some heterogeneity in the onset of viremia. These results suggest that the likelihood for successful infection of a ruminant host is affected by the number of infectious mosquitoes biting, but also highlights that a single bite of an infectious mosquito can result in disease. The per bite mosquito-to-host transmission efficiency was estimated at 28% (95% confidence interval: 15 - 47%). We subsequently combined this transmission efficiency with estimates for life traits of Aedes aegypti or related mosquitoes into a Ross-McDonald mathematical model to illustrate scenarios under which major RVFV outbreaks could occur in naïve populations (i.e., R0 >1). The model revealed that relatively high vector-to-host ratios as well as mosquitoes feeding preferably on competent hosts are required for R0 to exceed 1. Altogether, this study highlights the importance of experiments that mimic natural exposure to RVFV. The experiments facilitate a better understanding of the natural progression of disease and a direct way to obtain epidemiological parameters for mathematical models.
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Affiliation(s)
- Gebbiena M. Bron
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, Netherlands
| | | | - Mart C. M. de Jong
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, Netherlands
| | - Lucien van Keulen
- Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, Netherlands
| | - Rianka P. M. Vloet
- Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, Netherlands
| | | | - Jeroen Kortekaas
- Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, Netherlands
| | - Quirine A. ten Bosch
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, Netherlands
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Tinto B, Quellec J, Cêtre-Sossah C, Dicko A, Salinas S, Simonin Y. Rift Valley fever in West Africa: A zoonotic disease with multiple socio-economic consequences. One Health 2023; 17:100583. [PMID: 37664171 PMCID: PMC10474305 DOI: 10.1016/j.onehlt.2023.100583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/12/2023] [Accepted: 06/12/2023] [Indexed: 09/05/2023] Open
Abstract
Rift Valley fever virus (RVFV) is an arbovirus that causes Rift Valley fever (RVF), a zoonotic disease that mainly affects domestic and wildlife ruminants and humans. The first epidemic in North-Western and West Africa occurred in Senegal and Mauritania in 1987, two countries where RVF is now endemic. Slaughterhouse workers, farmers, herders and veterinarians are at high risk of exposure to RVF. Beyond the health threat, RVF is considered to cause major socio-economic problems, specifically in developing countries where livestock farming and trade are important economic activities. Indeed, the mortality rate linked to RVF infection can reach 95-100% in newborns and young animals. In West Africa, livestock production is a key factor for food production and for national economics. Epizootics caused by RVF can therefore have serious socio-economic consequences by impacting multisectoral economics, the psycho-social health of pastoral communities, and food security. Improving prevention strategies against RVF, including vaccination, enhancing knowledge of RVF and correcting any inappropriate behaviors by populations of endemics areas, as well as better monitoring of RVF ecological factors are effective ways to better foresee and control outbreaks of RVF and its socio-economical side-effects in countries at high risk of occurrence of the disease.
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Affiliation(s)
- Bachirou Tinto
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- Laboratoire National de Référence des Fièvres Hémorragiques Virale, Centre MURAZ, Institut National de Santé Publique (INSP), Bobo-Dioulasso, Burkina Faso
| | - Jordan Quellec
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- ASTRE, University of Montpellier, CIRAD, INRAe, Montpellier, France
| | | | - Amadou Dicko
- Laboratoire central de référence, Institut National de Santé Publique (INSP), Ouagadougou, Burkina Faso
- Ministère de l'Agriculture, des ressources animales et halieutiques du Burkina Faso, Ouagadougou, Burkina Faso
| | - Sara Salinas
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
| | - Yannick Simonin
- Pathogenesis and Control of Chronic and Emerging Infections, University of Montpellier, INSERM, Etablissement Français du Sang, Montpellier, France
- ASTRE, University of Montpellier, CIRAD, INRAe, Montpellier, France
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Bian T, Hao M, Zhao X, Zhao C, Luo G, Zhang Z, Fu G, Yang L, Chen Y, Wang Y, Yu C, Yang Y, Li J, Chen W. A Rift Valley fever mRNA vaccine elicits strong immune responses in mice and rhesus macaques. NPJ Vaccines 2023; 8:164. [PMID: 37891181 PMCID: PMC10611786 DOI: 10.1038/s41541-023-00763-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
Rift Valley fever virus (RVFV) is listed as a priority pathogen by the World Health Organization (WHO) because it causes serious and fatal disease in humans, and there are currently no effective countermeasures. Therefore, it is urgent to develop a safe and efficacious vaccine. Here, we developed six nucleotide-modified mRNA vaccines encoding different regions of the Gn and Gc proteins of RVFV encapsulated in lipid nanoparticles, compared their ability to induce immune responses in mice and found that mRNA vaccine encoding the full-length Gn and Gc proteins had the strongest ability to induce cellular and humoral immune responses. IFNAR(-/-) mice vaccinated with mRNA-GnGc were protected from lethal RVFV challenge. In addition, mRNA-GnGc induced high levels of neutralizing antibodies and cellular responses in rhesus macaques, as well as antigen-specific memory B cells. These data demonstrated that mRNA-GnGc is a potent and promising vaccine candidate for RVFV.
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Affiliation(s)
- Ting Bian
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture and Rural Affairs, Nanjing, China
- Frontier Biotechnology Laboratory, Zhejiang University-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, China
| | - Meng Hao
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Xiaofan Zhao
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Chuanyi Zhao
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Gang Luo
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Zhendong Zhang
- School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China
| | - Guangcheng Fu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Lu Yang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Yi Chen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Yudong Wang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Changming Yu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China
| | - Yilong Yang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China.
| | - Jianmin Li
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China.
- Frontier Biotechnology Laboratory, Zhejiang University-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, China.
| | - Wei Chen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing, 100071, China.
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Cecilia H, Vriens R, Wichgers Schreur PJ, de Wit MM, Métras R, Ezanno P, ten Bosch QA. Heterogeneity of Rift Valley fever virus transmission potential across livestock hosts, quantified through a model-based analysis of host viral load and vector infection. PLoS Comput Biol 2022; 18:e1010314. [PMID: 35867712 PMCID: PMC9348665 DOI: 10.1371/journal.pcbi.1010314] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 08/03/2022] [Accepted: 06/16/2022] [Indexed: 01/17/2023] Open
Abstract
Quantifying the variation of pathogens’ life history traits in multiple host systems is crucial to understand their transmission dynamics. It is particularly important for arthropod-borne viruses (arboviruses), which are prone to infecting several species of vertebrate hosts. Here, we focus on how host-pathogen interactions determine the ability of host species to transmit a virus to susceptible vectors upon a potentially infectious contact. Rift Valley fever (RVF) is a viral, vector-borne, zoonotic disease, chosen as a case study. The relative contributions of livestock species to RVFV transmission has not been previously quantified. To estimate their potential to transmit the virus over the course of their infection, we 1) fitted a within-host model to viral RNA and infectious virus measures, obtained daily from infected lambs, calves, and young goats, 2) estimated the relationship between vertebrate host infectious titers and probability to infect mosquitoes, and 3) estimated the net infectiousness of each host species over the duration of their infectious periods, taking into account different survival outcomes for lambs. Our results indicate that the efficiency of viral replication, along with the lifespan of infectious particles, could be sources of heterogeneity between hosts. Given available data on RVFV competent vectors, we found that, for similar infectious titers, infection rates in the Aedes genus were on average higher than in the Culex genus. Consequently, for Aedes-mediated infections, we estimated the net infectiousness of lambs to be 2.93 (median) and 3.65 times higher than that of calves and goats, respectively. In lambs, we estimated the overall infectiousness to be 1.93 times higher in individuals which eventually died from the infection than in those recovering. Beyond infectiousness, the relative contributions of host species to transmission depend on local ecological factors, including relative abundances and vector host-feeding preferences. Quantifying these contributions will ultimately help design efficient, targeted, surveillance and vaccination strategies. Viruses spread by mosquitoes present a major threat to animal and public health worldwide. When these pathogenic viruses can infect multiple species, controlling their spread becomes difficult. Rift Valley fever virus (RVFV) is such a virus. It spreads predominantly among ruminant livestock but can also spill over and cause severe disease in humans. Understanding which of these ruminant species are most important for the transmission of RVFV can help for effective control. One piece of this puzzle is to assess how effective infected animals are at transmitting RVFV to mosquitoes. To answer this question, we combine mathematical models with observations from experimental infections in cattle, sheep, and goats, and model changes in viremia over time within individuals. We then quantify the relationship between hosts’ viremia and the probability to infect mosquitoes. In combining these two analyses, we estimate the overall transmission potential of sheep, when in contact with mosquitoes, to be 3 to 5 times higher than that of goats and cattle. Further, sheep that experience a lethal infection have an even larger overall transmission potential. Once applied at the level of populations, with setting-specific herd composition and exposure to mosquitoes, these results will help unravel species’ role in RVF outbreaks.
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Affiliation(s)
- Hélène Cecilia
- INRAE, Oniris, BIOEPAR, Nantes, France
- * E-mail: (HC); (QAtB)
| | - Roosmarie Vriens
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - Mariken M. de Wit
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Raphaëlle Métras
- Sorbonne Université, INSERM, Institut Pierre Louis d’Epidémiologie et de Santé Publique (IPLESP), Paris, France
| | | | - Quirine A. ten Bosch
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, The Netherlands
- * E-mail: (HC); (QAtB)
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Safety and immunogenicity of four-segmented Rift Valley fever virus in the common marmoset. NPJ Vaccines 2022; 7:54. [PMID: 35585071 PMCID: PMC9117246 DOI: 10.1038/s41541-022-00476-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 04/05/2022] [Indexed: 11/08/2022] Open
Abstract
Rift Valley fever virus (RVFV) is an emerging mosquito-borne bunyavirus that is highly pathogenic to wild and domesticated ruminants, camelids, and humans. While animals are exclusively infected via mosquito bites, humans can also be infected via contact with contaminated tissues or blood. No human vaccine is available and commercialized veterinary vaccines do not optimally combine efficacy with safety. We previously reported the development of two novel live-attenuated RVF vaccines, created by splitting the M genome segment and deleting the major virulence determinant NSs. The vaccine candidates, referred to as the veterinary vaccine vRVFV-4s and the human vaccine hRVFV-4s, were shown to induce protective immunity in multiple species after a single vaccination. Anticipating accidental exposure of humans to the veterinary vaccine and the application of hRVFV-4s to humans, the safety of each vaccine was evaluated in the most susceptible nonhuman primate model, the common marmoset (Callithrix jacchus). Marmosets were inoculated with high doses of each vaccine and were monitored for clinical signs as well as for vaccine virus dissemination, shedding, and spreading to the environment. To accurately assess the attenuation of both vaccine viruses, separate groups of marmosets were inoculated with the parent wild-type RVFV strains. Both wild-type strains induced high viremia and disseminated to primary target organs, associated with mild-to-severe morbidity. In contrast, both vaccines were well tolerated with no evidence of dissemination and shedding while inducing potent neutralizing antibody responses. The results of the studies support the unprecedented safety profile of both vaccines for animals and humans.
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Stoek F, Rissmann M, Ulrich R, Eiden M, Groschup MH. Black rats (Rattus rattus) as potential reservoir hosts for Rift Valley fever phlebovirus: Experimental infection results in viral replication and shedding without clinical manifestation. Transbound Emerg Dis 2022; 69:1307-1318. [PMID: 33794070 DOI: 10.1111/tbed.14093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/05/2021] [Accepted: 03/29/2021] [Indexed: 12/01/2022]
Abstract
Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that can cause severe disease in ruminants and humans. Epidemics occur mainly after heavy rainfall, which leads to a significant increase in the occurrence of RVFV-transmitting mosquitoes. During inter-epidemic periods, the virus is assumed to be maintained between mosquitoes, susceptible livestock and yet unknown wildlife. The widespread rodent Rattus rattus (black rat) has been suspected to be involved in RVFV maintenance. In order to elucidate its susceptibility and thus its possible role in the transmission cycle of the virus, an experimental infection study was performed. Black rats were subcutaneously infected with highly virulent RVFV strain 35/74 and euthanized on days 3, 14 and 28 post-infection. Additional black rats served as non-infected contact animals. The infected black rats showed high susceptibility to RVFV infection. Generation of RVFV-neutralizing antibodies was found, and the rats developed viraemias lasting up to 17 days. Viral RNA was found in tissues until the last day of the experiment. However, neither a clinical manifestation nor virus-induced histopathological lesions were observed in any rat. These findings indicate the persistence of RVFV in black rats without affecting the animals. In contact animals, no evidence of horizontal RVFV transmission was found, although the co-housed infected rats showed oral, rectal and conjunctival RVFV shedding. Results of this study point to an involvement of black rats in the RVFV transmission cycle, and further studies are needed to investigate their potential role in the maintenance of the virus.
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Affiliation(s)
- Franziska Stoek
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Melanie Rissmann
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
- Department of Viroscience, Erasmus MC, Rotterdam, Netherlands
| | - Reiner Ulrich
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
- Faculty of Veterinary Medicine, Institute of Veterinary-Pathology, Universität Leipzig, Leipzig, Germany
| | - Martin Eiden
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Martin H Groschup
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
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Kain MP, Skinner EB, van den Hurk AF, McCallum H, Mordecai EA. Physiology and ecology combine to determine host and vector importance for Ross River virus. eLife 2021; 10:e67018. [PMID: 34414887 PMCID: PMC8457839 DOI: 10.7554/elife.67018] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 08/19/2021] [Indexed: 01/19/2023] Open
Abstract
Identifying the key vector and host species that drive the transmission of zoonotic pathogens is notoriously difficult but critical for disease control. We present a nested approach for quantifying the importance of host and vectors that integrates species' physiological competence with their ecological traits. We apply this framework to a medically important arbovirus, Ross River virus (RRV), in Brisbane, Australia. We find that vertebrate hosts with high physiological competence are not the most important for community transmission; interactions between hosts and vectors largely underpin the importance of host species. For vectors, physiological competence is highly important. Our results identify primary and secondary vectors of RRV and suggest two potential transmission cycles in Brisbane: an enzootic cycle involving birds and an urban cycle involving humans. The framework accounts for uncertainty from each fitted statistical model in estimates of species' contributions to transmission and has has direct application to other zoonotic pathogens.
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Affiliation(s)
- Morgan P Kain
- Department of Biology, Stanford UniversityStanfordUnited States
- Natural Capital Project, Woods Institute for the Environment, Stanford UniversityStanfordUnited States
| | - Eloise B Skinner
- Department of Biology, Stanford UniversityStanfordUnited States
- Centre for Planetary Health and Food Security, Griffith UniversityGold CoastAustralia
| | - Andrew F van den Hurk
- Public Health Virology, Forensic and Scientific Services, Department of HealthBrisbaneAustralia
| | - Hamish McCallum
- Centre for Planetary Health and Food Security, Griffith UniversityGold CoastAustralia
| | - Erin A Mordecai
- Department of Biology, Stanford UniversityStanfordUnited States
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Oymans J, Wichgers Schreur PJ, van Keulen L, Kant J, Kortekaas J. Rift Valley fever virus targets the maternal-foetal interface in ovine and human placentas. PLoS Negl Trop Dis 2020; 14:e0007898. [PMID: 31961862 PMCID: PMC6994196 DOI: 10.1371/journal.pntd.0007898] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 01/31/2020] [Accepted: 11/01/2019] [Indexed: 01/10/2023] Open
Abstract
Background Rift Valley fever virus (RVFV) is an arbovirus of the order Bunyavirales that causes severe disease in ruminants and humans. Outbreaks in sheep herds are characterised by newborn fatalities and abortion storms. The association of RVFV infections with abortions of ovines and other ruminants is well recognized, whereas the pathology resulting in abortion has remained undescribed. Accumulating evidence suggests that RVFV is abortogenic in humans as well, warranting more research on the interaction of RVFV with the ruminant and human placenta. Methodology/Principal findings Pregnant ewes were inoculated with a highly virulent strain of RVFV and necropsied at different days post infection. Tissues were collected and analysed by PCR, virus isolation, and immunohistochemistry. The results show that RVFV replicates efficiently in maternal placental epithelial cells before the virus infects foetal trophoblasts. Moreover, the virus was shown to bypass the maternal epithelial cell layer by directly targeting foetal trophoblasts in the haemophagous zone, a region of the ovine placenta where maternal blood is in direct contact with foetal cells. Abortion was associated with widespread necrosis of placental tissues accompanied with severe haemorrhages. Experiments with human placental explants revealed that the same virus strain replicates efficiently in both cyto- and syncytiotrophoblasts. Conclusions/Significance This study demonstrates that RVFV targets the foetal-maternal interface in both ovine and human placentas. The virus was shown to cross the ovine placental barrier via two distinct routes, ultimately resulting in placental and foetal demise followed by abortion. Our finding that RVFV replicates efficiently in human trophoblasts underscores the risk of RVFV infection for human pregnancy. Rift Valley fever virus (RVFV) is a mosquito-borne RNA virus that causes severe disease in ruminants, wildlife and humans in Africa and the Arabian Peninsula. Outbreaks are characterised by high mortality rates among newborn lambs and abortion storms in sheep herds. The severe outcome of RVFV infection during pregnancy in livestock is well documented, whereas the pathological changes that result in abortion have not yet been described. To investigate how RVFV crosses the placenta and how infection results in abortion, pregnant ewes were infected with RVFV and target cells in maternal and foetal tissues were identified at different time points after inoculation. We show that epithelial cells of the ovine placenta and foetal trophoblasts are primary target cells of RVFV and that placental demise is the primary cause of abortion. The same RVFV strain was shown to replicate efficiently in human placental explants, targeting both cyto- and syncytiotrophoblasts.
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Affiliation(s)
- Judith Oymans
- Wageningen Bioveterinary Research, Houtribweg, Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University & Research, Wageningen, The Netherlands
| | | | - Lucien van Keulen
- Wageningen Bioveterinary Research, Houtribweg, Lelystad, The Netherlands
| | - Jet Kant
- Wageningen Bioveterinary Research, Houtribweg, Lelystad, The Netherlands
| | - Jeroen Kortekaas
- Wageningen Bioveterinary Research, Houtribweg, Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University & Research, Wageningen, The Netherlands
- * E-mail:
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Abstract
Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that was first discovered in Kenya in 1930 and is now endemic throughout multiple African countries and the Arabian Peninsula. RVF virus primarily infects domestic livestock (sheep, goats, cattle) causing high rates of neonatal mortality and abortion, with human infection resulting in a wide variety of clinical outcomes, ranging from self-limiting febrile illness to life-threatening haemorrhagic diatheses, and miscarriage in pregnant women. Since its discovery, RVF has caused many outbreaks in Africa and the Arabian Peninsula with major impacts on human and animal health. However, options for the control of RVF outbreaks are limited by the lack of licensed human vaccines or therapeutics. For this reason, RVF is prioritized by the World Health Organization for urgent research and development of countermeasures for the prevention and control of future outbreaks. In this review, we highlight the current understanding of RVF, including its epidemiology, pathogenesis, clinical manifestations and status of vaccine development.
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Affiliation(s)
- Daniel Wright
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- The Jenner Institute, University of Oxford, Oxford OX1 2JD, UK
| | - Jeroen Kortekaas
- Wageningen Bioveterinary Research, Lelystad, The Netherlands
- Laboratory of Virology, Wageningen University, Wageningen, The Netherlands
| | - Thomas A. Bowden
- Wellcome Centre for Human Genetics, Division of Structural Biology, University of Oxford, Oxford OX1 2JD, UK
| | - George M. Warimwe
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford OX1 2JD, UK
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Odendaal L, Clift SJ, Fosgate GT, Davis AS. Lesions and Cellular Tropism of Natural Rift Valley Fever Virus Infection in Adult Sheep. Vet Pathol 2018; 56:61-77. [DOI: 10.1177/0300985818806049] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Rift Valley fever (RVF) is a mosquito-borne disease that affects both ruminants and humans, with epidemics occurring more frequently in recent years in Africa and the Middle East, probably as a result of climate change and intensified livestock trade. Sheep necropsied during the 2010 RVF outbreak in South Africa were examined by histopathology and immunohistochemistry (IHC). A total of 124 sheep were available for study, of which 99 cases were positive for RVF. Multifocal-random, necrotizing hepatitis was confirmed as the most distinctive lesion of RVF cases in adult sheep. Of cases where liver, spleen, and kidney tissues were available, 45 of 70 had foci of acute renal tubular epithelial injury in addition to necrosis in both the liver and spleen. In some cases, acute renal injury was the most significant RVF lesion. Immunolabeling for RVFV was most consistent and unequivocal in liver, followed by spleen, kidney, lung, and skin. RVFV antigen-positive cells included hepatocytes, adrenocortical epithelial cells, renal tubular epithelial cells, macrophages, neutrophils, epidermal keratinocytes, microvascular endothelial cells, and vascular smooth muscle. The minimum set of specimens to be submitted for histopathology and IHC to confirm or exclude a diagnosis of RVFV are liver, spleen, and kidney. Skin from areas with visible crusts and lung could be useful additional samples. In endemic areas, cases of acute renal tubular injury should be investigated further if other more common causes of renal lesions have already been excluded. RVFV can also cause an acute infection in the testis, which requires further investigation.
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Affiliation(s)
- Lieza Odendaal
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, Gauteng, South Africa
| | - Sarah J. Clift
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, Gauteng, South Africa
| | - Geoffrey T. Fosgate
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, Gauteng, South Africa
| | - A. Sally Davis
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, Gauteng, South Africa
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
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Rift Valley fever in animals and humans: Current perspectives. Antiviral Res 2018; 156:29-37. [PMID: 29857007 DOI: 10.1016/j.antiviral.2018.05.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/21/2018] [Accepted: 05/24/2018] [Indexed: 02/03/2023]
Abstract
Rift Valley fever (RVF) is an ecologically complex emerging arboviral disease that causes significant illness in both livestock and people. This review article is designed to assist the reader in understanding the varied aspects of RVF disease in animals and humans. The historical facets of RVF disease, including the evolution of human outbreaks, are presented and discussed. The different clinical presentations of human RVF disease and the underlying causes are then addressed. We explore the exposure and transmission potential of RVF in animals and people. In the concluding section, we discuss the historical role of RVF as a biological weapon. We conclude with an outline of the important unanswered questions for ongoing research into this important zoonotic disease.
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Vloet RPM, Vogels CBF, Koenraadt CJM, Pijlman GP, Eiden M, Gonzales JL, van Keulen LJM, Wichgers Schreur PJ, Kortekaas J. Transmission of Rift Valley fever virus from European-breed lambs to Culex pipiens mosquitoes. PLoS Negl Trop Dis 2017; 11:e0006145. [PMID: 29281642 PMCID: PMC5760105 DOI: 10.1371/journal.pntd.0006145] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 01/09/2018] [Accepted: 12/01/2017] [Indexed: 12/21/2022] Open
Abstract
Background Rift Valley fever virus (RVFV) is a mosquito-borne bunyavirus of the genus Phlebovirus that is highly pathogenic to ruminants and humans. The disease is currently confined to Africa and the Arabian Peninsula, but globalization and climate change may facilitate introductions of the virus into currently unaffected areas via infected animals or mosquitoes. The consequences of such an introduction will depend on environmental factors, the availability of susceptible ruminants and the capacity of local mosquitoes to transmit the virus. We have previously demonstrated that lambs native to the Netherlands are highly susceptible to RVFV and we here report the vector competence of Culex (Cx.) pipiens, the most abundant and widespread mosquito species in the country. Vector competence was first determined after artificial blood feeding of laboratory-reared mosquitoes using the attenuated Clone 13 strain. Subsequently, experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs were performed. Finally, the transmission of RVFV from viremic lambs to mosquitoes was studied. Principal findings Artificial feeding experiments using Clone 13 demonstrated that indigenous, laboratory-reared Cx. pipiens mosquitoes are susceptible to RVFV and that the virus can be transmitted via their saliva. Experiments with wild-type RVFV and mosquitoes hatched from field-collected eggs confirmed the vector competence of Cx. pipiens mosquitoes from the Netherlands. To subsequently investigate transmission of the virus under more natural conditions, mosquitoes were allowed to feed on RVFV-infected lambs during the viremic period. We found that RVFV is efficiently transmitted from lambs to mosquitoes, although transmission was restricted to peak viremia. Interestingly, in the mosquito-exposed skin samples, replication of RVFV was detected in previously unrecognized target cells. Significance We here report the vector competence of Cx. pipiens mosquitoes from the Netherlands for RVFV. Both laboratory-reared mosquitoes and well as those hatched from field-collected eggs were found to be competent vectors. Moreover, RVFV was transmitted efficiently from indigenous lambs to mosquitoes, although the duration of host infectivity was found to be shorter than previously assumed. Interestingly, analysis of mosquito-exposed skin samples revealed previously unidentified target cells of the virus. Our findings underscore the value of including natural target species in vector competence experiments. The consequences of first introductions of mosquito-borne viruses into previously unaffected areas depend on environmental factors, the availability of susceptible hosts and local vector populations. We have previously demonstrated that sheep breeds native to the Netherlands are highly susceptible to Rift Valley fever virus (RVFV), a mosquito-borne virus that causes severe outbreaks among domesticated ruminants and humans in Africa and the Arabian Peninsula. To gain further insight into the risk of a future RVFV introduction into the Netherlands, we have now investigated the vector competence of Cx. pipiens, the most abundant mosquito species in the country. Vector competence was first determined after artificial blood feeding and subsequently after feeding on viremic lambs. The results from artificial feeding experiments suggested that indigenous Cx. pipiens mosquitoes are competent vectors. The vector competence of Cx. pipiens was confirmed after feeding on viremic lambs. Transmission from lambs to mosquitoes was found to be very efficient, although largely confined to peak viremia. The localized inflammatory response resulting from mosquito bites was associated with enhanced virus replication in the skin.
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Affiliation(s)
- Rianka P. M. Vloet
- Department of Virology, Wageningen Bioveterinary Research, Lelystad, the Netherlands
| | | | | | - Gorben P. Pijlman
- Laboratory of Virology, Wageningen University, Wageningen, the Netherlands
| | - Martin Eiden
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Greifswald—Insel Riems, Germany
| | - Jose L. Gonzales
- Department of Bacteriology and Epidemiology, Wageningen Bioveterinary Research, Lelystad, the Netherlands
| | | | | | - Jeroen Kortekaas
- Department of Virology, Wageningen Bioveterinary Research, Lelystad, the Netherlands
- * E-mail:
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