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Rift Valley fever in Mozambique

epidemiology, diagnostics and vaccine use

Moiane, Belisário Tomé (2017). Rift Valley fever in Mozambique. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2017:84
ISBN 978-91-7760-058-9
eISBN 978-91-7760-059-6
[Doctoral thesis]

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Official URL: http://pub.epsilon.slu.se/

Abstract

Background: Rift Valley fever (RVF) is an arthropod-borne disease that causes huge losses among livestock in Africa and Arabic Peninsula, due to high death and abortion rates. RVF phlebovirus (RVFPV) also infects humans, raising public health concerns worldwide. RVF is endemic in Mozambique however, outbreaks were just reported in the south. In this thesis, we have analyzed the serological status of domestic ruminants, and African buffaloes, identified RVFPV mosquito vectors in Gaza province, evaluated the stability of a formalin RVFPV vaccine stored at different temperatures in Mozambique and evaluated RVFPV antigens for oral immunization of mice.

Materials and methods: Blood samples were collected from cattle (n = 2724), goats (n = 1283), sheep (n = 148), and African buffaloes (n = 69), between February 2010 and May 2011 (study I), in 2013 and 2014 in the three regions of Mozambique (study II), and 2014 to 2016 in Gaza (study III), furthermore, mosquito trapping was performed for morphological identification and RVFPV detection (study III). Serological status of the herds was achieved by ELISA and PRNT. In study IV we evaluated the stability of a formalin-inactivated RVFPV-vaccine treated in four different temperature conditions, by assessing the antibody response in animal groups A-D. Two RVFPV antigens (N and ∆Gn proteins) were expressed in Arabidopsis thaliana plants and administered orally to mice in two experiments (n =4, each group and n = 8 in the control) (study V).

Results and discussion: RVFPV seropositivity rate ranged from 7% to 36.9%. The seroprevalences in livestock and African buffaloes were high suggesting that RVFPV is actively circulating in Mozambique. Culex, Anopheles, and Mansonia were abundant potential vectors of RVFPV; Members of Culex genus were found to carry RVFPV, however, identification down to species was not performed; the formalin-inactivated vaccine elicited strong and long-lasting antibody response in cattle, irrespectively of the storage condition; A. thaliana plants successfully expressed RVF antigens, which in turn induced strong antibody responses in mice. Further studies on the use of these antigens in ruminants are pending investigations.

Conclusions: (1) RVFPV is actively circulating among livestock and African buffaloes in Mozambique which requires a continuous and intensified surveillance; (2) a member of Culex genus is a candidate vector for RVFPV in South Mozambique; (3) formalin-inactivated RVFPV vaccine used for cattle in Mozambique is stable; (4) RVFPV antigens expressed in A. thaliana plants elicited strong antibody response in mice and are eligible for use as vaccine candidates.

Authors/Creators:Moiane, Belisário Tomé
Title:Rift Valley fever in Mozambique
Subtitle:epidemiology, diagnostics and vaccine use
Alternative abstract:
LanguageAbstract
UNSPECIFIED

Bakgrund: Rift Valley feber (RVF) är en artropod-vektorburen sjukdom i Afrika och på Arabiska halvön, RVF orsakar hög dödlighet och hög abortfrekvens och därmed stora förluster bland boskap. RVF phlebovirus (RVFPV) infekterar också människor, vilket globalt uppmärksammas som ett folkhälsoproblem. RVF är endemisk i Moçambique men utbrott har bara rapporterats i de södra delarna. I denna studie har vi analyserat serologisk status hos tama idisslare och hos Afrikansk buffel, identifierat myggvektorer för RVFPV i Gaza-provinsen, utvärderat stabiliteten hos ett formalininaktiverat RVFPV-vaccin lagrat vid olika temperaturer under fältförhållanden i Moçambique och utvärderat RVFPV-antigener för oral immunisering av möss.
Material och metoder: Blodprover insamlades från nötkreatur (n = 2724), getter (n = 1283), får (n = 148) och Afrikansk Buffel (n = 69), mellan februari 2010 och maj 2011 (studie I), under 2013 och 2014 i tre regionerna i Moçambique (studie II) och under 2014-2016 i Gaza (studie III). Vidare så fångades mygg för morfologisk identifiering och för påvisande av RVFPV (studie III). I studie IV utvärderade vi stabiliteten hos en formalininaktiverad RVFPV-vaccin som behandlats vid fyra olika temperaturer, genom att bedöma antikroppssvaret i djurgrupperna A-D. Serologisk undersökning av djuren gjordes med ELISA och PRNT. Två RVFPV-antigener (N och ΔGn-proteiner) som uttrycktes i Arabidopsis thaliana-växter administrerades oralt till möss i två experiment (n = 4 i varje grupp och n = 8 i kontrollen) (studie V)
Resultat och diskussion: Seroprevalensen för RVFPV varierade från 7% till 36,9% och den höga prevalensen hos boskap och Afrikansk buffel tyder på en aktiv cirkulation av RVFPV i Moçambique. Culex, Anopheles och Mansonia var rikligt förekommande potentiella vektorer för RVFPV. Culex-släktet påvisades bära RVFPV, men identifiering ned till underart utfördes inte; det formalininaktiverade vaccinet framkallade ett starkt och långvarigt antikroppssvar hos nötkreatur, oberoende av lagringsförhållandet. A. thaliana-växter uttryckte framgångsrikt RVF-antigener, vilket i sin tur gav upphov till ett starkt antikroppsvar hos möss. Ytterligare studier behövs om användningen av dessa antigener hos idisslare.
Slutsatser: (1) RVFPV cirkulerar aktivt bland boskap och Afrikansk buffel i Moçambique vilket kräver en intensiv övervakning; (2) en underart av Culex släktet är en kandidat som vektor av RVFPV i södra Moçambique; (3) formalininaktiverat RVFPV-vaccin som används till boskap i Moçambique är stabilt; (4) RVFPV-antigener uttryckta i A. thaliana-växter framkallar ett starkt antikroppssvar hos möss och är en tänkbar vaccinkandidat.

Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2017
Depositing date:20 December 2017
Volume:2017:84
Number of Pages:80
Papers/manuscripts:
NumberReferences
ILagerqvist, N.*, Moiane, B., Mapaco, L., Fafetine, J., Vene, S., Falk, K.I. (2013). Antibodies against Rift Valley fever virus in cattle, Mozambique. Emerging Infectious Diseases 19(7), 1177-1179.
IIMoiane, B.*, Mapaco, L., Thompson, P., Berg, M., Albihn, A., Fafetine, J. (2017). High seroprevalence of Rift Valley fever phlebovirus in domestic ruminants and African Buffaloes in Mozambique shows need for intensified surveillance. Infection Ecology & Epidemiology 7(1):1416248.
IIIMoiane, B.*, Mapaco, L., Fafetine, J., Macandza, G., Beti, D.J., Cholleti, H., Berg, M., Albihn, A. (2017). Identification of the Rift Valley fever phlebovirus vectors in South Mozambique (submitted).
IVLagerqvist, N.*, Moiane, B., Bucht, G., Fafetine, J., Paweska, J.T., Lundkvist, Å., Falk, K.I.(2012). Stability of a formalin-inactivated Rift Valley fever vaccine: Evaluation of a vaccination campaign for cattle in Mozambique. Vaccine 30(2012), 6534-6540.
VKalbina, I.*, Lagerqvist, N., Moiane, B., Ahlm, C., Andersson, S., Strid, Å., Falk, K.I. (2016). Arabidopsis thaliana plants expressing Rift Valley fever virus antigens: Mice exhibit systemic immune responses as the result of oral administration of transgenic plants. Protein Expression and Purification 127(2016), 61-67.
Place of Publication:Uppsala
Publisher:Department of Biomedical Sciences and Veterinary Public Health, Faculty of Veterinary Medicine and Animal Sciences, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-058-9
ISBN for electronic version:978-91-7760-059-6
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 3 Medical and Health Sciences > 304 Medical Biotechnology > Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Pathobiology
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Other Veterinary Science
Agrovoc terms:arabidopsis thaliana, mosquitoes, vectors
Keywords:Rift Valley fever phlebovirus, Arabidopsis thaliana, RVF antigens, seroprevalence, mosquito vectors, cattle, goats, sheep, African buffaloes, Mozambique
URN:NBN:urn:nbn:se:slu:epsilon-e-4585
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4585
ID Code:14924
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Biomedical Sciences and Veterinary Public Health
Deposited By: Mr. Belisário Moiane
Deposited On:21 Dec 2017 08:55
Metadata Last Modified:11 Jan 2018 09:37
Project info:
Name:Impact of Zoonotic Disease in Public Health In Mozambique
Programme:Program 2

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