Mopeia Virus–related Arenavirus, Morogoro, Tanzania | CDC EID

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Volume 15, Number 12–December 2009
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Mopeia Virus–related Arenavirus in Natal Multimammate Mice, Morogoro, Tanzania
Stephan Günther, Guy Hoofd, Remi Charrel, Christina Röser, Beate Becker-Ziaja, Graham Lloyd, Christopher Sabuni, Ron Verhagen, Guido van der Groen, Jan Kennis, Abdul Katakweba, Robert Machang'u, Rhodes Makundi, and Herwig Leirs
Author affiliations: Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany (S. Günther, B. Becker-Ziaja); Institute of Tropical Medicine Leopold II, Antwerp, Belgium (G. Hoofd, G. van der Groen); Université de la Méditerranée, Marseille, France (R. Charrel); Artus Company, Hamburg (C. Röser); Centre for Emergency Preparedness and Response, Salisbury, UK (G. Lloyd); Sokoine University of Agriculture, Morogoro, Tanzania (C. Sabuni, A. Katakweba, R. Machang'u, R. Makundi); University of Antwerp Department of Biology, Antwerp (R. Verhagen, J. Kennis, H. Leirs); and University of Aarhus Department of Integrated Pest Management, Kongens Lyngby, Denmark (H. Leirs)

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Abstract
A serosurvey involving 2,520 small mammals from Tanzania identified a hot spot of arenavirus circulation in Morogoro. Molecular screening detected a new arenavirus in Natal multimammate mice (Mastomys natalensis), Morogoro virus, related to Mopeia virus. Only a small percentage of mice carry Morogoro virus, although a large proportion shows specific antibodies.

Arenaviruses are segmented negative-strand RNA viruses. Their natural hosts are various rodent species. The virus family comprises several human pathogens causing hemorrhagic fever, namely Machupo, Guanarito, Junin, Sabia, and Chapare viruses in South America, and Lassa and Lujo viruses in Africa (1–3). In addition, Africa harbors arenaviruses that are not linked with human disease: Mobala, Ippy, Mopeia, and Kodoko viruses (4–7). We conducted a systematic search in wildlife in Tanzania to identify new African arenaviruses.

The Study
During 1985 through 1989, a total of 2,520 small mammals were live-trapped in different regions of Tanzania. After species determination, they were measured and bled by orbital puncture. Serum samples were tested by indirect immunofluorescent antibody (IFA) assay (8). Lassa virus was used as antigen due to its cross-reactivity with immune sera from animals infected with other arenaviruses (4,6). Clusters of seropositivity were found in Arvicanthis spp. rodents from the Iringa region (20%) and in Natal multimammate mice (Mastomys natalensis) from Arusha (18%) and Morogoro (17%) (Table 1), which suggests that these animals are reservoirs of arenaviruses. Titers ranged from 16 to 512 and 16 to 4,096 in Arvicanthis spp. rodents and M. natalensis mice, respectively. Peak prevalence in M. natalensis mice was found on the campus of the Sokoine University in Morogoro (23.7% of 746 animals collected over several seasons).

In 2004, M. natalensis mice were trapped in a mosaic of maize fields and fallow grassland at the university campus in the city of Morogoro (6°50´34.9794´´S; 37°38´8.232´´E) to identify the virus. The animal voucher specimens were deposited at the Royal Museum of Central Africa, Tervuren, Belgium. RNA was prepared from 10 mL of rodent serum by using the QIAamp Viral RNA kit (QIAGEN, Valencia, CA, USA), and screening was performed by using a pan–Old World arenavirus reverse transcription–PCR (RT-PCR) specific for the large (L) gene (9). One of 96 serum samples was positive (no. 3017/2004) (Table 2), and sequencing of the PCR fragment showed a new arenavirus sequence. The virus was isolated in Vero cells and called Morogoro virus (strain 3017/2004).

For sequencing, the isolate was propagated in T75 flasks, virus particles in supernatant were pelleted by ultracentrifugation, and RNA was isolated by using the QIAamp Viral RNA kit (QIAGEN). The entire 3.5-kb small (S) RNA segment was amplified by RT-PCR as described previously (10). The 7-kb L RNA segment was amplified in 2 fragments by using a long-range RT-PCR protocol and primers targeting the conserved termini of L RNA and Morogoro virus–specific primers designed on the basis of the sequence of the fragment detected by RT-PCR screening. By using the PCR products as a template, short overlapping fragments were amplified and sequenced with a set of consensus primers for Old World arenaviruses, and S and L RNA sequences were assembled (GenBank accession nos. EU914103 and EU914104). (Sequences reported in this article have been submitted to GenBank and assigned the following accession numbers: full-length S and L RNA sequences of Morogoro virus, EU914103–04; partial L gene sequences of Morogoro virus, EU914107–22; cytochrome B gene of Morogoro virus-positive Mastomys natalensis, EU914105–06.)

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