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Managing hytrosavirus infections in Glossina pallidipes colonies: feeding regime affects the prevalence of salivary gland hypertrophy syndrome.

Abd-Alla AM, Kariithi HM, Mohamed AH, Lapiz E, Parker AG, Vreysen MJ - PLoS ONE (2013)

Bottom Line: Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections.We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources.The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9) virus copies in regular colonies to an average of 10(2.5) and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach.

View Article: PubMed Central - PubMed

Affiliation: Insect Pest Control Laboratory, Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture, Vienna, Austria. a.m.m.abd-alla@iaea.org

ABSTRACT
Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH) syndrome and the virus isolated from Glossina pallidipes (GpSGHV) has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. Due to the deleterious impact of SGHV on G. pallidipes colonies, several approaches were investigated to develop a virus management strategy. Horizontal virus transmission is the major cause of the high prevalence of the GpSGHV in tsetse colonies. Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections. However, due to the absence of disposable feeding equipment (feeding trays and silicone membranes), the implementation of a clean feeding approach remains economically difficult. We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources. The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9) virus copies in regular colonies to an average of 10(2.5) and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach. The clean feeding approach also reduced the virus load from an average of 10(8) virus copy numbers to an average of 10(3) virus copies and SGH prevalence of 10% to 4% in flies fed after the clean fed colony. Taken together, these data indicate that the clean feeding approach is applicable in large-scale G. pallidipes production facilities and eliminates the deleterious effects of the virus and the SGH syndrome in these colonies.

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Related in: MedlinePlus

Prevalence of SGH in different tsetse colonies of G. pallidipes.The flies were randomly selected at different time points from the different colonies and dissected to determine status of the salivary glands. Numbers between brackets are the mean SGH prevalence percentage. The line is the smoothed regression.
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pone-0061875-g001: Prevalence of SGH in different tsetse colonies of G. pallidipes.The flies were randomly selected at different time points from the different colonies and dissected to determine status of the salivary glands. Numbers between brackets are the mean SGH prevalence percentage. The line is the smoothed regression.

Mentions: Two protocols for feeding the Seibersdorf Tororo flies were used: 1) the standard membrane feeding protocol [19], whereby successive cages with flies were offered a blood meal on the same membrane, and 2) a “clean blood feeding protocol” (hereafter denoted as “clean feeding”), whereby each cage of flies was provided with new, sterile defibrinated cow blood at each meal [19] (Figure 1). The clean feeding protocol was used to prevent the flies from picking up the virus from the blood already used for feeding previous cages. To implement the clean feeding protocol in the large-scale colony, newly-emerged (teneral) G. pallidipes flies from the regular Seibersdorf Tororo colony were offered a clean blood meal and thereafter these flies and their progeny were always the first to be fed on fresh, clean blood during the entire period of the experiment. This colony was denoted as “clean feeding colony 1″ (CFC-1), and was expanded by addition of teneral flies emerging from the CFC-1 parents until the maximum number of cages that could be fed first (during one round of feeding) on available feeding trays was attained. Subsequently, when the maximum number of cages for the CFC-1 colony was attained, the excess flies from the CFC-1 progeny were fed on the same membrane as a second feeding round after feeding the CFC-1 colony. This second-round fed group of flies was denoted as “clean feeding colony 2″ (CFC-2), and was always maintained on a second feeding round after feeding the CFC-1 colony throughout the entire experimental period. During the establishment of the CFC-1 and CFC-2, the regular colony was always fed on the same membranes used to feed CFC-1 and -2 (at the third and subsequent feeding rounds), and was denoted as “normal feeding colony” (NFC).


Managing hytrosavirus infections in Glossina pallidipes colonies: feeding regime affects the prevalence of salivary gland hypertrophy syndrome.

Abd-Alla AM, Kariithi HM, Mohamed AH, Lapiz E, Parker AG, Vreysen MJ - PLoS ONE (2013)

Prevalence of SGH in different tsetse colonies of G. pallidipes.The flies were randomly selected at different time points from the different colonies and dissected to determine status of the salivary glands. Numbers between brackets are the mean SGH prevalence percentage. The line is the smoothed regression.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646844&req=5

pone-0061875-g001: Prevalence of SGH in different tsetse colonies of G. pallidipes.The flies were randomly selected at different time points from the different colonies and dissected to determine status of the salivary glands. Numbers between brackets are the mean SGH prevalence percentage. The line is the smoothed regression.
Mentions: Two protocols for feeding the Seibersdorf Tororo flies were used: 1) the standard membrane feeding protocol [19], whereby successive cages with flies were offered a blood meal on the same membrane, and 2) a “clean blood feeding protocol” (hereafter denoted as “clean feeding”), whereby each cage of flies was provided with new, sterile defibrinated cow blood at each meal [19] (Figure 1). The clean feeding protocol was used to prevent the flies from picking up the virus from the blood already used for feeding previous cages. To implement the clean feeding protocol in the large-scale colony, newly-emerged (teneral) G. pallidipes flies from the regular Seibersdorf Tororo colony were offered a clean blood meal and thereafter these flies and their progeny were always the first to be fed on fresh, clean blood during the entire period of the experiment. This colony was denoted as “clean feeding colony 1″ (CFC-1), and was expanded by addition of teneral flies emerging from the CFC-1 parents until the maximum number of cages that could be fed first (during one round of feeding) on available feeding trays was attained. Subsequently, when the maximum number of cages for the CFC-1 colony was attained, the excess flies from the CFC-1 progeny were fed on the same membrane as a second feeding round after feeding the CFC-1 colony. This second-round fed group of flies was denoted as “clean feeding colony 2″ (CFC-2), and was always maintained on a second feeding round after feeding the CFC-1 colony throughout the entire experimental period. During the establishment of the CFC-1 and CFC-2, the regular colony was always fed on the same membranes used to feed CFC-1 and -2 (at the third and subsequent feeding rounds), and was denoted as “normal feeding colony” (NFC).

Bottom Line: Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections.We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources.The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9) virus copies in regular colonies to an average of 10(2.5) and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach.

View Article: PubMed Central - PubMed

Affiliation: Insect Pest Control Laboratory, Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture, Vienna, Austria. a.m.m.abd-alla@iaea.org

ABSTRACT
Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH) syndrome and the virus isolated from Glossina pallidipes (GpSGHV) has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. Due to the deleterious impact of SGHV on G. pallidipes colonies, several approaches were investigated to develop a virus management strategy. Horizontal virus transmission is the major cause of the high prevalence of the GpSGHV in tsetse colonies. Implementation of a "clean feeding" regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections. However, due to the absence of disposable feeding equipment (feeding trays and silicone membranes), the implementation of a clean feeding approach remains economically difficult. We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources. The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 10(9) virus copies in regular colonies to an average of 10(2.5) and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach. The clean feeding approach also reduced the virus load from an average of 10(8) virus copy numbers to an average of 10(3) virus copies and SGH prevalence of 10% to 4% in flies fed after the clean fed colony. Taken together, these data indicate that the clean feeding approach is applicable in large-scale G. pallidipes production facilities and eliminates the deleterious effects of the virus and the SGH syndrome in these colonies.

Show MeSH
Related in: MedlinePlus