ANTIBODIES TO ARBOVIRUSES IN HOUSE SPARROWS ( PASSER DOMESTICUS ) IN THE CZECH

Jufiicová Z. , I . Li terák, J . Pinowski : Antibodies to Arboviruses in House Sparrows (Passer domesticus) in the Czech Republic. Acta Vet. Brno 2000, 69: 213–215. From 1995 to 1997, house sparrows (Passer domesticus) (n = 273) from suburban area close to Kunín in the northeastern part of the Czech Republic were examined by using a haemagglutination-inhibition test (positive titre ≥ 20) for the presence of antibodies to arboviruses. Antibodies to Sindbis alphavirus, West Nile flavivirus, tick-borne encephalitis flavivirus, ËahyÀa bunyavirus, and âalovo bunyavirus were detected at seroprevalences of 2.2 %, 5.5 %, 1.8 %, 14.7 %, and 2.2 %, respectively. The study area seems to be an endemic focus of the ËahyÀa bunyavirus occurrence. Alphavirus, Flavivirus, Bunyavirus, seroprevalence, wild birds Wild birds may serve as a reservoir of arboviruses in central Europe (Aspöck et al.1973; Hubá lek et al. 1989). From this point of view, abundant synanthropic house sparrows were tested only few times (Ernek and Lichard 1964; Ernek et al. 1968; S ix l et al. 1973; Jufi icová et al. 1998). However, in our opinion, house sparrow is the most suitable species of wild birds for studying occurrence of various arboviruses in urban and suburban areas. The reasons are its high fidelity to a locality, continuous exposition to arbovirus vectors, and easy catchability of representative numbers of sparrows for testing. For three years, we tested house sparrows from one Czech locality for the presence of antibodies to five arboviruses in order to verify the idea to use such testing for the monitoring of the arbovirus occurrences in the environment. The results of our investigation are presented in this study. Materials and Methods House sparrows were captured with mist-nets in a suburban agricultural area in a small village Kunín near Nov ̆ Jiãín in the northeastern part of the Czech Republic. Birds were captured, killed and bled every November from 1995 to 1997. Blood sera of sparrows were examined for antibodies to Sindbis alphavirus (SIN), West Nile flavivirus (WN), tick-borne encephalitis flavivirus (Central European encephalitis serogroup) (TBE), ËahyÀa bunyavirus (California serogroup) (TAH) and âalovo bunyavirus (CVO). Sera were examined by using the haemagglutination-inhibition test in accordance with the method described elsewhere (Jufi icová et al. 1998). For the preparation of antigens, SIN EgAr 339 SM 16, WN EgAr 101 SM 12, TAH 92 SM 12 and CVO 184 SM7 strains were used (Hubálek et al. 1989). The TBE antigen was a commercially available “HA TBE Antigen” (IMUNA, Slovak Republic). Titres of 20 and higher were considered significantly positive. Four haemagglutination units were used in the test. All the antigens used were tested prior to the haemagglutinationinhibition test with homologous and heterologous positive sera to eliminate nonspecific haemagglutination. No cross-reactions between antigens were observed. ACTA VET. BRNO 2000, 69: 213–215 Address for correspondence: Doc. MVDr. Ivan Literák, CSc. Department of Infectious Diseases and Epizootiology, Faculty of Veterinary Medicine University of Veterinary and Pharmaceutical Sciences, Palackého 1-3, 612 42 Brno, Czech Republic Phone ++420-5-41 56 23 07 Fax: ++420-5-74 88 41 E-mail: literaki@vfu.cz http://www.fvu.cz/acta-vet/actavet.htm Results and Discussion A total of 273 house sparrows were examined. Antibodies to SIN, WN, TBE, TAH and CVO were detected at prevalences of 2.2 %, 5.5 %, 1.8 %, 14.7 % and 2.2 %, respectively (Table 1). Titres ranged from 20 to 160. Titres of antibodies to flaviviruses are shown in Table 2. All the examined arboviruses occurred in the studied area. Results of our serological survey in house sparrows mostly correspond to a similar study in Poland where antibodies to SIN, WN, TBE, TAH and CVO were detected in house sparrows at seroprevalences of 1.1%, 2.8 %, 1.1%, 2.8% and 1.1%, respectively (Jufi icová et al. 1998). The only striking difference is between prevalences to TAH. In the Czech study area in Kunín, the prevalence to TAH was 14.7%. Near Warsaw, it was only 2.8%. We learned that not only sparrows but also humans from Kunín area and close surroundings are often exposed to TAH. The prevalence of virus neutralization antibodies to TAH of 20.6 % were found in the human inhabitans of that area and in summer 1970, six cases of the syndrome of human aseptic meningitis with a four-fold increase of antibodies to TAH were observed (Heinz et al. 1972). However, whether TAH or other studied viruses have an impact on the health status of sparrows remains unanswered. High prevalences of antibodies to ËahyÀa bunyavirus in both men and house sparrows suggests that the suburban area close to Kunín is an endemic focus of the ËahyÀa bunyavirus occurrence. The prevalences of arboviruses in birds are linked to the presence of specific vectors: various mosquitoes for SIN, WN, TAH, CVO and ticks Ixodes ricinus for TBE (Hubálek et al. 1989; Danielová 1990). These vectors had to attack the sparrows. Since the prevalences to studied arboviruses were not significantly different in various years, we suppose the similar amount of the attacks in the suburban environment in these years. 214 Sparrow No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 WN 40 20 40 40 20 20 20 80 40 20 40 40 80 20 20 TBE 20 20 20 40 20 Table 1 Prevalences of antibodies to arboviruses in house sparrows (Passer domesticus) in the Czech Republic Sindbis West Tick-borne ËahyÀa âalovo Year alphavirus Nile encephalitis bunyavirus bunyavirus flavivirus flavivirus 1995 2/74a 2/74 2/74 11/74 1/74 1996 1/54 3/54 1/54 8/54 1/54 1997 3/145 10/145 2/145 21/145 4/145 Total 6/273 15/273 5/237 40/273 6/273 % 2.2 5.5 1.8 14.7 2.2 Significance of differencesb NS NS NS NS NS a Positive/tested b Differences between seroprevalences in individual years were tested using χ2 test NS Not significant Table 2 Titres of antibodies to flaviviruses (WN = West Nile flavivirus, TBE = tick-borne encephalitis flavivirus) in seropositive house sparrows (Passer domesticus) Protilátky proti arbovirÛm u vrabcÛ domácích (Passer domesticus) v âeské republice Vrabci domácí (Passer domesticus) pocházející z vesnického, zemûdûlského prostfiedí Kunína (okr. Nov ̆ Jiãín) byli v letech 1995 aÏ 1997 vy‰etfiováni na pfiítomnost protilátek proti arbovirÛm. Hemaglutinaãnû-inhibiãním testem byla vy‰etfiena séra 273 vrabcÛ. Za pozitivní byl povaÏován titr ≥ 20. Protilátky proti alphaviru Sindbis byly detekovány v 2,2 % prevalenci, proti flaviviru West Nile v 5,5 % prevalenci, proti viru klí‰Èové encefalitidy v 1,8 % prevalenci, proti bunyaviru ËahyÀa v 14,7 % prevalenci a proti bunyaviru âalovo v 2,2 % prevalenci. Kunínsko se zdá b ̆t endemick ̆m ohniskem v ̆skytu bunyaviru ËahyÀa.

. However, in our opinion, house sparrow is the most suitable species of wild birds for studying occurrence of various arboviruses in urban and suburban areas.The reasons are its high fidelity to a locality, continuous exposition to arbovirus vectors, and easy catchability of representative numbers of sparrows for testing.For three years, we tested house sparrows from one Czech locality for the presence of antibodies to five arboviruses in order to verify the idea to use such testing for the monitoring of the arbovirus occurrences in the environment.The results of our investigation are presented in this study.

Materials and Methods
House sparrows were captured with mist-nets in a suburban agricultural area in a small village Kunín near NovJ iãín in the northeastern part of the Czech Republic.Birds were captured, killed and bled every November from 1995 to 1997.
For the preparation of antigens, SIN EgAr 339 SM 16, WN EgAr 101 SM 12, TAH 92 SM 12 and CVO 184 SM7 strains were used (H ubálek et al. 1989).The TBE antigen was a commercially available "HA TBE Antigen" (IMUNA, Slovak Republic).Titres of 20 and higher were considered significantly positive.Four haemagglutination units were used in the test.All the antigens used were tested prior to the haemagglutinationinhibition test with homologous and heterologous positive sera to eliminate nonspecific haemagglutination.No cross-reactions between antigens were observed.

Results and Discussion
A total of 273 house sparrows were examined.Antibodies to SIN, WN, TBE, TAH and CVO were detected at prevalences of 2.2 %, 5.5 %, 1.8 %, 14.7 % and 2.2 %, respectively (Table 1).Titres ranged from 20 to 160.Titres of antibodies to flaviviruses are shown in Table 2.All the examined arboviruses occurred in the studied area.
Results of our serological survey in house sparrows mostly correspond to a similar study in Poland where antibodies to SIN, WN, TBE, TAH and CVO were detected in house sparrows at seroprevalences of 1.1%, 2.8 %, 1.1%, 2.8% and 1.1%, respectively (Jufiicová et al. 1998).The only striking difference is between prevalences to TAH.In the Czech study area in Kunín, the prevalence to TAH was 14.7%.Near Warsaw, it was only 2.8%.We learned that not only sparrows but also humans from Kunín area and close surroundings are often exposed to TAH.The prevalence of virus neutralization antibodies to TAH of 20.6 % were found in the human inhabitans of that area and in summer 1970, six cases of the syndrome of human aseptic meningitis with a four-fold increase of antibodies to TAH were observed (Heinz et al. 1972).However, whether TAH or other studied viruses have an impact on the health status of sparrows remains unanswered.High prevalences of antibodies to ËahyÀa bunyavirus in both men and house sparrows suggests that the suburban area close to Kunín is an endemic focus of the ËahyÀa bunyavirus occurrence.
Wild birds may serve as a reservoir of arboviruses in central Europe (A s p ö c k et al.1973; H u b á l e k et al. 1989).From this point of view, abundant synanthropic house sparrows were tested only few times (E r n e k and L i c h a r d 1964; E r n e k et al. 1968; S i x l et al. 1973; J u fi i c o v á et al.

Table 1
Prevalences of antibodies to arboviruses in house sparrows (Passer domesticus) in the Czech Republic Titres of antibodies to flaviviruses (WN = West Nile flavivirus, TBE = tick-borne encephalitis flavivirus) in seropositive house sparrows (Passer domesticus)