sign in sign up
<<
Home , Medical entomology

1st Regional meeting of the new phase of the MediLabSecure project January 20-24, 2020 - Institut Pasteur, Dakar, Senegal

Update of strains circulating in Tunisia and Algeria: One Health perspective Fares Wasfi1,2,4, M’ghirbi Youmna1,3,4, Hachid Aissam5, Gdoura Mariem1,2,4, Touzi Henda1,2,4, Benbetka Chahrazed5, Fayez Khardine5, Benallal Kamel6, Benbetka Sihem6, Harrat Zoubir6, Bouattour Ali1,3,4, Triki Henda1,2,4. 1: Virus Hosts Laboratory, Pasteur Institute of Tunis, Tunisia. 2: Department of Clinical , Pasteur Institute of Tunis, Tunisia. 3: Department of Medical Entomology, Pasteur Institute of Tunis, TUNISIA. 4: University of Tunis El Manar, Tunis, TUNISIA. 5: Laboratory of , Pasteur Institute of Algeria, Algiers, ALGERIA. 6: Laboratory of Medical Entomology, Pasteur Institute of Algeria, Algiers, ALGERIA.

Background

West Nile virus (WNV) is a -borne flavivirus mainly transmitted by mosquitoes in sylvatic cycles involving birds, as amplifying host, and bird-feeding mosquitoes, as vectors. Humans and equines are considered as incidental dead-end hosts. WNV is recognized as one of the most widespread arbovirus in the Mediterranean basin region and worldwide with major public health concerns [1]. Many neuroinvasives outbreaks were notified since the mid 1990’s in Maghreb including Algeria (1994) and

Tunisia (1997, 2012, 2018). Serological and molecular studies on humans, equines, birds Human sampling in 2019 and mosquitoes as well as virus detection in the vector showed an intensive circulation of Mosquitoes sampling in2019 Horses sampling in2019 WNV in Tunisia [1-4] and Algeria [5-7]. North African WNV strains (Tunisia, Morocco) were Human sampling in2018 Mosquitoes sampling in2018 typed and belonged to sub-lineage WNV-1a; however, epidemiological data regarding Horses sampling in2018 WNV circulation in North Africa is still limited. Mosquitoes sampling in2017 Figure1. Humans, mosquitoes and horses sampling Our study aimed to further develop the epidemiological status of the WNV in Tunisia and Algeria. Molecular investigation was performed in order to characterize the WNV strains Table1. Serological and molecular investigations results circulating in human and mosquito’s population surrounding clinical cases. In addition, Humans Mosquitoes Horses serological investigation was conducted on horses in coastal region in Tunisia. Countries Years (qRT-PCR) (qRT-PCR) (ELISA- IgG) Tunisia 2018 48 confirmed 11 pos pools 48/86 (56%) Materials and methods 23 sequences 5 sequences Sampling of human urine, adult mosquitoes and horses sera are presented in Figure 1. 2019 07 confirmed 2 pos pools 27/49 (55%) Positive WNV real-time PCR urine and mosquitoes pools were selected for WNV genetic 03 sequences 0 sequences characterization based on amplification and sequencing of a partial structural region of Algeria 2017 5 pos pools WNV genome (Figure 2). Phylogenetic tree was performed including all genotypes 2 sequences described worldwide (WNV-1 to 5 and WNV-7). Two different methods were conducted: Neighbor joining analysis method with the 2019 2 confirmed 1 sequence Kimura 2-parameter model and Maximum parsimony. The tree topology was supported by 1000 bootstrap replicates and Usutu virus (USUV, NC006551) sequence was used as out- group. Genetic distances were calculated using the neighbor-joining and p-distance methods. 233-FW: 5'-TTGTGTTGGCTCTCTTGGCGTTCTT-3‘ 640c-Rev: 5'-CAGCCGACAGCACTGGGCATTCATA-3' Results and Discussion Figure 2. Targeted structural region for genetic characterization

Amplification was successfully obtained for 57 human and 18 mosquitoe’s samples and Figure3a 99 65 Lineage1

68 99 PCR products were successfully sequenced (Table1). 53 Lineage2 65 Lineage7 Lineage4 99 Lineage3 Lineage5 The obtained sequences with 358-nucleotide-long fragment were compared to each other NC006551.USUV and to WNV sequences isolated previously in Tunisia Algeria and worldwide. 2 MU42.TUN2018 Mu6.TUN2018 MU65.TUN2018 MU130.TUN2018 The phylogenetic tree (Figure 3a) showed, as expected, a clear distribution of the Mu74.TUN2018 Mu78.TUN2018 V3.TUN2018 sequences according to the viral lineage. Tunisian and Algerian WNV sequences grouped MU69.TUN2018 Mu128.TUN2018 Mu73.TUN2018 MU22.TUN2019 within the WNV-1a sub-lineage in one Mediterranean sub-cluster, similarly to the Mu55.TUN2018 Mu109.TUN2018 Mu124.TUN2018 sequence identified during the Tunisia 1997 outbreak. However, the newly obtained Mu03.TUN2018 67 MU41.TUN2018 MU23.TUN2018 sequences were grouped together in a single cluster, independently from the other Mu58.TUN2018 62 Mu118.TUN2018 DQ786573.FRA2004 sequences within the 1a sub-lineage (Figure 3b). Mu54.TUN2018 98 P1.DZ2017 P5.DZ2017 These results may indicate the emergence of a new variant within the 1a sub-lineage that Mu103.TUN2018 Mu119.TUN2018 Mu10.TUN2018 caused the 2018 Outbreak in Tunisia and 2019 sporadic cases in Tunisia and Algeria. 58 395.DZ2019 Mu120.TUN2018

56 V97.TUN2018 Unfortunately, these sequences could not compare to those circulating in Europe and the V154.TUN2018 V153.TUN2018 V75.TUN2018 Mu139.TUN2018 Mediterranean basin. Indeed (i) several published sequences have targeted different 81 MU18.TUN2019 MU24.TUN2019 KC131125.ISR2011 genomic regions (NS3 and NS5 regions) and (ii) no WNV-lineage 1 sequence from 2018 GU246710.ISR2008 58 FJ483549.ITA2008 HM138725.ITA2009 was published. GU011992.ITA2009 AF404757.ITA1998 JF707789.SPA2008 AY701413.MOR2003 AJ965626.PRT2004 Serological investigation in horses revealed high seroprevalence with 56% and 55% in FJ766332.SPA2007 AY701412.MOR1996 66 KF647253.ITA2013 84 KC954092.ITA2012 2018 and 2019 respectively. JX556213.ITA2012 GU246655.ISR2002 GU246660.ISR2003 These results corroborate with those previously reported in Tunisia and Algeria [1, 4, 5]. 62 JQ928175.ITA2011 JN858069.ITA2011 Mediteranean subtype AY268132.FRA2000 68 56 Our serological investigation in equines (Table 1) associated to recently and previous KY703854.SEN1990 73 AY262283.KEN1998 GU246701.ISR2007 serological data favor the endemic circulation of WNV in Tunisia, Algeria and the 73 77 AF260969.ROU1996 76 AF317203.RUS1999 AY278442.RUS2000 surrounding Mediterranean areas. HM152775.ISR2000 GQ851608.CAF1967 AY660002.MEX2003 MH508015.USA2011 GQ851607.NGA1965 65 AY268133.TUN1997 52 AF481864.ISR1998 Conclusion AY646354.USA2002 AF404754.USA2000 DQ164205.USA2002 DQ211652.USA1999 Sublineage.1a DQ080054.USA2003 80 JX070655.TJK Our work highlights the need of standardization of molecular characterization approaches AY603654.ETH1976 100 JX041628.AZE1970 Sublineage.1b JX041630.AZE1967 and strengthening regional and international collaborations to better elucidate the EU081844.EGY1951 GQ851603.AUS1991 dynamics of circulation of WNV to prevent the reoccurrence and spread of the humans 0.002 and animals in North Africa and the Mediterranean region. Figure3: Phylogenetic tree References 1- Benjelloun A, El Harrak M, Belkadi B. 2016. West Nile disease in north-west Africa: bibliographical review. Transbound Emerg Dis;63:153–9. 2- Bahri O, Dhifallah I, Ben Alaya-Bouafif N, Fekih H, Gargouri J, Triki H. 2010. Sero-epidemiological study of West Nile virus circulation in human in Tunisia. Bull Soc Pathol Exot ;104:272–6. 3- Fares W, Dachraoui K,Cherni S, Barhoumi W, Chelbi I, Derbali M, Zoghlami Z, Zhioua E. 2016. Detection of West Nile virus in Culex mosquitoes, Tunisia, 2014. Acta Tropica,159: 106-110. 4- Hammami S, Hassine TB, Conte A, Amdouni J, De Massis F, Sghaier S, et al. 2017. West Nile disease in Tunisia: an overview of 60 years. Vet Ital;53:225–34. 5- Lafri I, Prat CM, Bitam I, Gravier P, Besbaci M, Zeroual F, et al. 2017. Seroprevalence of West Nile virus antibodies in equids in the northeast of Algeria and detection of virus circulation in 2014. Comp Immunol Microbiol Infect Dis;50:8–12. 6- Benbetka S, Hachid A, Benallal KE, Benbetka C, Khaldi A, Bitam I, Harrat Z. . 2018. First field evidence of Culex perexiguus by West Nile virus in Sahara Oasis of Algeria. J Vector Borne DisOct-Dec;55(4):305-309. 7- Hachid A, Beloufa MA, Seghier M, Bahoura N, Dia M, Fall G, Sall AA. 2019 . Evidence of West Nile virus circulation among humans in central northern Algeria. New Microbes New Infect. Mar 8;29:100512. .