Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks
Abstract
:1. Introduction
2. Materials and Methods
2.1. Collection Sites
2.2. Field Activities
2.3. Laboratory Activities
2.3.1. Virus Isolates
- BTV-2, strain 2000TE8341: It was isolated from the spleen of a Sardinian sheep that died because of BTV in 2000. The strain was passed once onto the Kc cell line and three times onto VERO cells (from African green monkey kidney) before use.
- BTV-4 ITA, strain 2014TE31172: It was isolated from the blood of a sheep infected with BTV in the Apulia region in 2014. The strain was passed once onto the Kc cell line and three times onto VERO cells before use.
- BTV-4 MOR, strain MOR2009-07: Kindly provided by the Pirbright Institute (Lara Harrup), it was isolated from a blood sample of a BTV-infected sheep in Morocco in 2009. This strain was passed three times onto the Kc cell line and twice onto VERO cells before use.
- BTV-8, strain UKG2007-82: Kindly provided by the Pirbright Institute (Lara Harrup), it was isolated from a blood sample of a bovine infected in the UK in 2007. The strain was passed three times onto the Kc cell line and twice onto VERO cells before use.
2.3.2. Culicoides Oral Infection
2.3.3. Species Identification
2.3.4. Virus Detection
2.4. Statistical Analysis
3. Results
3.1. Feeding Rate
3.2. Competence Studies
4. Discussion
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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BTV-4 ITA | Fed via Hemotek | Fed via Cotton Pledget | |||||||
SPECIES | SITE | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi |
Culicoides obsoletus/scoticus | Abruzzo | 5 | 9139 | 0.05 | 4 | 566 | 3923 | 14.43 | 190 |
Culicoides obsoletus/scoticus | Lazio | 229 | 752 | 30.45 | 186 | ||||
Culicoides imicola | Sardinia | 1107 | 54,471 | 2.03 | 359 | 330 | 2078 | 15.88 | 258 |
Culicoides imicola | Calabria | 0 | 2586 | 0 | 0 | 400 | 2196 | 18.21 | 269 |
BTV-2 | Fed via Hemotek | Fed via Cotton Pledget | |||||||
SPECIES | SITE | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi |
Culicoides obsoletus/scoticus | Abruzzo | 4 | 4131 | 0.1 | 1 | 447 | 4589 | 9.74 | 226 |
Culicoides obsoletus/scoticus | Lazio | 173 | 516 | 33.53 | 75 | ||||
Culicoides imicola | Sardinia | 719 | 71,843 | 1 | 257 | 351 | 3376 | 10.40 | 228 |
Culicoides imicola | Calabria | 0 | 1213 | 0 | 0 | 337 | 2426 | 13.89 | 219 |
BTV-8 | Fed via Hemotek | Fed via Cotton Pledget | |||||||
SPECIES | SITE | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi |
Culicoides obsoletus/scoticus | Abruzzo | 174 | 484 | 35.95 | 110 | ||||
Culicoides obsoletus/scoticus | Lazio | 77 | 185 | 41.62 | 61 | ||||
Culicoides imicola | Sardinia | 190 | 57,318 | 0.33 | 107 | 153 | 1593 | 9.6 | 125 |
Culicoides imicola | Calabria | 165 | 402 | 41.04 | 117 | ||||
BTV-4 MOR | Fed via Hemotek | Fed via Cotton Pledget | |||||||
SPECIES | SITE | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi | ENGORGED | TOTAL NUMBER | FEEDING RATE (%) | 10 dpi |
Culicoides obsoletus/scoticus | Abruzzo | 168 | 720 | 23.33 | 126 | ||||
Culicoides obsoletus/scoticus | Lazio | 87 | 278 | 31.29 | 64 | ||||
Culicoides imicola | Sardinia | 178 | 26,863 | 0.66 | 120 | ||||
Culicoides imicola | Calabria | 153 | 471 | 32.48 | 116 | ||||
Culicoides obsoletus/scoticus | SUBTOTAL | 9 | 13,270 | 0.07 | 5 | 1921 | 11,447 | 16.78 | 1038 |
Culicoides imicola | SUBTOTAL | 2194 | 214,294 | 1.02 | 843 | 1889 | 12,542 | 15.06 | 1332 |
TOTAL | 2203 | 227,564 | 0.97 | 848 | 3810 | 23,989 | 15.88 | 2370 |
Virus | Minimum–Maximum Virus Titer TCID50 mL (Number of Blood Meals) |
---|---|
BTV-4 ITA | 105.3–106.54 (20) |
BTV-2 | 105.01–106.14 (22) |
BTV-8 | 105–106.3 (16) |
BTV-4 MOR | 105.68–106.39 (15) |
Serogroup-Specific RT PCR (Positive Midges Ct < 50) | Serotype-Specific RT PCR (Positive Midges Ct < 40) | ||||||||
---|---|---|---|---|---|---|---|---|---|
Feeding Method | BTV Strain | Population | Number of Tested | Number of Positive | Recovery Rate (%) | Ct Mean (Min–Max) | Number of Positive | Recovery Rate (%) | Ct Mean (Min–Max) |
cotton | 4 ITA | C. obsoletus/scoticus Abruzzo | 16 | 14 | 87.5 | 36 (31–44) | / | / | / |
cotton | 4 ITA | C. obsoletus/scoticus Lazio | 11 | 11 | 100 | 38 (36–39) | 11 | 100 | 33 (32–35) |
Hemotek | 4 ITA | C. imicola Sardinia | 35 | 33 | 94.3 | 37 (35–42) | 33 | 94.3 | 33 (30–36) |
cotton | 4 ITA | C. imicola Sardinia | 10 | 8 | 80 | 40 (38–42) | 8 | 80 | 35 (33–37) |
cotton | 4 ITA | C. imicola Calabria | 15 | 15 | 100 | 39 (36–42) | 15 | 100 | 33 (31–36) |
cotton | 2 | C. obsoletus/scoticus Abruzzo | 15 | 12 | 80 | 37 (33–42) | 1 | 6.7 | 39 (39–39) |
cotton | 2 | C. obsoletus/scoticus Lazio | 11 | 11 | 100 | 38 (36–39) | 11 | 100 | 34 (33–35) |
Hemotek | 2 | C. imicola Sardinia | 21 | 19 | 90.5 | 39 (36–43) | 18 | 85.7 | 34 (32–39) |
cotton | 2 | C. imicola Sardinia | 14 | 7 | 50 | 43 (41–44) | 4 | 28.6 | 38 (36–39) |
cotton | 2 | C. imicola Calabria | 12 | 12 | 100 | 40 (35–43) | 12 | 100 | 35 (32–38) |
cotton | 8 | C. obsoletus/scoticus Abruzzo | 17 | 12 | 70.6 | 42 (39–47) | 7 | 41.2 | 35 (34–36) |
cotton | 8 | C. obsoletus/scoticus Lazio | 7 | 4 | 57.1 | 41 (39–42) | 2 | 28.6 | 36 (34–37) |
Hemotek | 8 | C. imicola Sardinia | 9 | / | / | / | 8 | 88.9 | 35 (32–37) |
cotton | 8 | C. imicola Sardinia | 13 | / | / | / | 9 | 69.2 | 36 (35–37) |
cotton | 8 | C. imicola Calabria | 15 | 13 | 86.7 | 39 (37–41) | 13 | 86.7 | 35 (33–37) |
cotton | 4 MOR | C. obsoletus/scoticus Abruzzo | 13 | 10 | 76.9 | 42 (38–49) | 10 | 76.9 | 35 (33–38) |
cotton | 4 MOR | C. obsoletus/scoticus Lazio | 8 | 7 | 87.5 | 40 (37–47) | 7 | 87.5 | 33 (31–35) |
Hemotek | 4 MOR | C. imicola Sardinia | 6 | 6 | 100 | 36 (34–38) | 6 | 100 | 31 (29–32) |
cotton | 4 MOR | C. imicola Calabria | 14 | 14 | 100 | 39 (36–41) | 13 | 92.9 | 34 (31–37) |
Serogroup-Specific RT PCR (Positive Midges Ct < 50) | Serotype-Specific RT PCR (Positive Midges Ct < 40) | ||||||
---|---|---|---|---|---|---|---|
Feeding Method | BTV Strain | Population | Number of Tested | Number of Positive | Ct Mean (Min–Max) | Number of Positive | Ct Mean (Min–Max) |
Hemotek | 4 ITA | C. obsoletus/scoticus Abruzzo | 4 | 0 | / | / | / |
cotton | 4 ITA | C. obsoletus/scoticus Abruzzo | 190 | 9 | 40 (34–46) | 1 | 29 (29–29) |
cotton | 4 ITA | C. obsoletus/scoticus Lazio | 186 | 18 | 41 (25–47) | 2 | 33 (27–39) |
Hemotek | 4 ITA | C. imicola Sardinia | 359 | 275 | 32 (24–48) | 253 | 30 (23–39) |
cotton | 4 ITA | C. imicola Sardinia | 258 | 17 | 36 (27–41) | 9 | 33 (27–38) |
cotton | 4 ITA | C. imicola Calabria | 269 | 15 | 40 (26–47) | 6 | 33 (24–37) |
Hemotek | 2 | C. obsoletus/scoticus Abruzzo | 1 | 0 | / | / | / |
cotton | 2 | C. obsoletus/scoticus Abruzzo | 226 | 6 | 38 (27–42) | 1 | 30 (30–30) |
cotton | 2 | C. obsoletus/scoticus Lazio | 75 | 9 | 38 (33–40) | 2 | 36 (33–38) |
Hemotek | 2 | C. imicola Sardinia | 257 | 186 | 32 (22–47) | 171 | 29 (23–39) |
cotton | 2 | C. imicola Sardinia | 228 | 16 | 40 (32–45) | 12 | 35 (30–39) |
cotton | 2 | C. imicola Calabria | 219 | 7 | 41 (28–45) | 2 | 32 (25–38) |
cotton | 8 | C. obsoletus/scoticus Abruzzo | 110 | 4 | 43 (39–46) | 1 | 38 (38–38) |
cotton | 8 | C. obsoletus/scoticus Lazio | 61 | 2 | 42 (39–44) | 0 | / |
Hemotek | 8 | C. imicola Sardinia | 107 | / | / | 56 | 30 (27–38) |
cotton | 8 | C. imicola Sardinia | 125 | / | / | 1 | 30 (30–30) |
cotton | 8 | C. imicola Calabria | 117 | 12 | 40 (31–44) | 1 | 34 (34–34) |
cotton | 4 MOR | C. obsoletus/scoticus Abruzzo | 126 | 0 | / | / | / |
cotton | 4 MOR | C. obsoletus/scoticus Lazio | 64 | 4 | 40 (38–43) | 0 | / |
Hemotek | 4 MOR | C. imicola Sardinia | 120 | 62 | 38 (31–45) | 59 | 32 (27–38) |
cotton | 4 MOR | C. imicola Calabria | 116 | 8 | 38 (33–43) | 6 | 32 (29–39) |
Serogroup-Specific RT-PCR | Serotype-Specific RT-PCR | ||||||
---|---|---|---|---|---|---|---|
Feeding Method | BTV Strain | Population | Number of Tested | Number of Positive with Ct < 50 (Recovery Rate%) | Number of Positive with Ct < Mean Ct at 0 dpi (Recovery Rate%) | Number of Positive with Ct < 40 (Recovery Rate%) | Number of Positive with Ct < Mean Ct at 0 dpi (Recovery Rate%) |
cotton | 4 ITA | C. obsoletus/scoticus Abruzzo | 190 | 9 (4.7) | 1 (0.5) | 1 (0.5) | / |
cotton | 4 ITA | C. obsoletus/scoticus Lazio | 186 | 18 (9.7) | 2 (1.1) | 2 (1.1) | 1 (0.5) |
Hemotek | 4 ITA | C. imicola Sardinia | 359 | 275 (76.6) | 201 (56) | 253 (70.5) | 165 (46) |
cotton | 4 ITA | C. imicola Sardinia | 258 | 17 (6.6) | 13 (5) | 9 (3.5) | 6 (2.3) |
cotton | 4 ITA | C. imicola Calabria | 269 | 15 (5.6) | 4 (1.5) | 6 (2.2) | 1 (0.4) |
cotton | 2 | C. obsoletus/scoticus Abruzzo | 226 | 6 (2.7) | 2 (0.9) | 1 (0.4) | 1 (0.4) |
cotton | 2 | C. obsoletus/scoticus Lazio | 75 | 9 (12.0) | 2 (2.7) | 2 (2.7) | 1 (1.3) |
Hemotek | 2 | C. imicola Sardinia | 257 | 186 (72.4) | 148 (57.6) | 171 (66.5) | 131 (51.4) |
cotton | 2 | C. imicola Sardinia | 228 | 16 (7.0) | 11 (4.8) | 12 (5.3) | 10 (4.4) |
cotton | 2 | C. imicola Calabria | 219 | 7 (3.2) | 2 (0.9) | 2 (0.9) | 1 (0.5) |
cotton | 8 | C. obsoletus/scoticus Abruzzo | 110 | 4 (3.6) | 2 (1.8) | 1 (0.9) | 0 (0) |
cotton | 8 | C. obsoletus/scoticus Lazio | 61 | 2 (3.3) | 1 (1.6) | 0 (0) | 0 (0) |
Hemotek | 8 | C. imicola Sardinia | 107 | / | / | 56 (52.3) | 54 (50.5) |
cotton | 8 | C. imicola Sardinia | 125 | / | / | 1 (0.8) | 1 (0.8) |
cotton | 8 | C. imicola Calabria | 117 | 12 (10.3) | 2 (1.7) | 1 (0.9) | 1 (0.9) |
cotton | 4 MOR | C. obsoletus/scoticus Abruzzo | 126 | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
cotton | 4 MOR | C. obsoletus/scoticus Lazio | 64 | 4 (6.3) | 2 (3.1) | 0 (0) | 0 (0) |
Hemotek | 4 MOR | C. imicola Sardinia | 120 | 62 (51.7) | 16 (13.3) | 59 (49.2) | 21 (17.5) |
cotton | 4 MOR | C. imicola Calabria | 116 | 8 (6.9) | 5 (4.3) | 6 (5.2) | 4 (3.4) |
Recovery Rate % (Confidence Intervals %) | ||||||
---|---|---|---|---|---|---|
RT-PCR | Population | Feeding Method | BTV-4 ITA | BTV-2 | BTV-8 | BTV-4 MOR |
Serogroup-specific RT-PCR | C. obsoletus/scoticus Abruzzo | Cotton | 0.5 (0.1–2.9) | 0.9 (0.3–3.1) | 1.8 (0.6–6.4) | 0 (0–2.3) |
C. obsoletus/scoticus Lazio | Cotton | 1.1 (0.3–3.8) | 2.7 (0.8–9.2) | 1.6 (0.4–8.7) | 3.1 (1–10.7) | |
C. imicola Sardinia | Hemotek | 56 (50.8–61) | 57.6 (51.5–63.5) | / | 13.3 (8.4–20.6) | |
Cotton | 5 (3–8.4) | 4.8 (2.7–8.4) | / | / | ||
C. imicola Calabria | Cotton | 1.5 (0.6–3.7) | 0.9 (0.3–3.2) | 1.7 (0.5–6) | 4.3 (1.9–9.7) | |
Serotype-specific RT-PCR | C. obsoletus/scoticus Abruzzo | Cotton | / | 0.4 (0.1–2.4) | 0 (0–2.7) | 0 (0–2.3) |
C. obsoletus/scoticus Lazio | Cotton | 0.5 (0.1–2.9) | 1.3 (0.3–7.1) | 0 (0–4.7) | 0 (0–4.5) | |
C. imicola Sardinia | Hemotek | 46 (40.9–51.1) | 51.4 (44.9–57) | 50.5 (41.1–59.8) | 17.5 (11.8–25.3) | |
Cotton | 2.3 (1.1–5) | 4.4 (2.4–7.9) | 0.8 (0.2–4.3) | / | ||
C. imicola Calabria | Cotton | 0.4 (0.1–2) | 0.5 (0.1–2.5) | 0.9 (0.2–4.6) | 3.4 (1.4–8.5) |
Dpi | BTV Strain | Site | Species | Number of Positive/Number of Tested | Recovery Rate % | Confidence Intervals % | CT Mean (Min–Max) |
---|---|---|---|---|---|---|---|
0 | 4 ITA | Abruzzo | C. obsoletus | 5/6 | 83.3 | / | 37 (32–44) |
C. scoticus | 8/9 | 88.9 | / | 34 (31–40) | |||
C. obsoletus/scoticus * | 1/1 | 100 | / | 41 (41–41) | |||
Lazio | C. obsoletus | 1/1 | 100 | / | 37 (37–37) | ||
C. scoticus | 10/10 | 100 | / | 38 (36–39) | |||
2 | Abruzzo | C. obsoletus | 2/2 | 100 | / | 38 (33–42) | |
C. scoticus | 10/12 | 83.3 | / | 37 (33–42) | |||
Lazio | C. obsoletus | 2/2 | 100 | / | 38 (36–39) | ||
C. scoticus | 9/9 | 100 | / | 38 (36–39) | |||
8 | Abruzzo | C. obsoletus | 6/8 | 75 | / | 42 (39–45) | |
C. scoticus | 4/7 | 57.1 | / | 42 (39–47) | |||
C. obsoletus/scoticus * | 2/2 | 100 | / | 41 (40–42) | |||
Lazio | C. obsoletus | 6/6 | 100 | / | 41 (41–42) | ||
C. scoticus | 1/1 | 100 | / | 39 (39–39) | |||
4 MOR | Abruzzo | C. obsoletus | 3/5 | 60 | / | 43 (40–48) | |
C. scoticus | 7/8 | 87.5 | / | 42 (38–49) | |||
Lazio | C. obsoletus | 3/4 | 75 | / | 39 (38–41) | ||
C. scoticus | 4/4 | 100 | / | 40 (37–47) | |||
10 | 4 ITA | Abruzzo | C. obsoletus | 1/14 | 7.1 | 1.7–31.9 | 34 (34–34) |
C. scoticus | 8/173 | 4.6 | 2.4–8.9 | 41 (37–46) | |||
C. obsoletus/scoticus * | 0/3 | 0 | / | / | |||
Lazio | C. obsoletus | 3/39 | 7.7 | 2.8–20.4 | 41 (38–43) | ||
C. scoticus | 15/146 | 10.3 | 6.4–16.3 | 40 (25–47) | |||
C. obsoletus/scoticus * | 0/1 | 0 | / | / | |||
2 | Abruzzo | C. obsoletus | 0/46 | 0 | 0.1–7.5 | / | |
C. scoticus | 6/178 | 3.4 | 1.6–7.2 | 38 (27–42) | |||
C. obsoletus/scoticus * | 0/2 | 0 | / | / | |||
Lazio | C. obsoletus | 2/16 | 12.5 | 3.8–36.4 | 36 (33–39) | ||
C. scoticus | 7/59 | 11.9 | 5.9–22.6 | 39 (37–40) | |||
8 | Abruzzo | C. obsoletus | 1/45 | 2.2 | 0.5–11.5 | 44 (44–44) | |
C. scoticus | 3/63 | 4.8 | 1.7–13.1 | 42 (39–46) | |||
C. obsoletus/scoticus * | 0/2 | 0 | / | / | |||
Lazio | C. obsoletus | 2/46 | 4.3 | 1.3–14.5 | 42 (39–44) | ||
C. scoticus | 0/15 | 0 | 0.2–20.6 | / | |||
4 MOR | Abruzzo | C. obsoletus | 0/22 | 0 | 0.1–14.8 | / | |
C. scoticus | 0/103 | 0 | 0–3.5 | / | |||
C. obsoletus/scoticus * | 0/1 | 0 | / | / | |||
Lazio | C. obsoletus | 2/28 | 7.1 | 2.2–22.8 | 41 (38–43) | ||
C. scoticus | 2/36 | 5.6 | 0.1–9.5 | 40 (39–41) |
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Federici, V.; Goffredo, M.; Mancini, G.; Quaglia, M.; Santilli, A.; Di Nicola, F.; De Ascentis, M.; Cabras, P.; Volpicelli, C.; De Liberato, C.; et al. Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks. Viruses 2019, 11, 941. https://doi.org/10.3390/v11100941
Federici V, Goffredo M, Mancini G, Quaglia M, Santilli A, Di Nicola F, De Ascentis M, Cabras P, Volpicelli C, De Liberato C, et al. Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks. Viruses. 2019; 11(10):941. https://doi.org/10.3390/v11100941
Chicago/Turabian StyleFederici, Valentina, Maria Goffredo, Giuseppe Mancini, Michela Quaglia, Adriana Santilli, Francesca Di Nicola, Matteo De Ascentis, Pierangela Cabras, Carmela Volpicelli, Claudio De Liberato, and et al. 2019. "Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks" Viruses 11, no. 10: 941. https://doi.org/10.3390/v11100941