Ultrastructural evidence for trans-ovum transmission of the DNA virus of tsetse,Glossina pallidipes (Diptera: Glossinidae)

Jura, Walter G. Z. O.; Otieno, L. H.; Chimtawi, M.

doi:10.1007/bf01568821

Cited by 34 publications

(21 citation statements)

References 8 publications

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“…GpSGHV induces a characteristic syndrome of SGH in its host, a property shared with two other viruses of Diptera described in Musca domestica (15) and Merodon equestris (6). It also induces lesions in gonads and accessory glands of male and female tsetse flies (38,39,59,60) and in the milk glands of females (61), which may be responsible for mother-to-offspring transmission. This specific tissue tropism for some target organs of adult flies reflects a close and very likely ancient adaptation of the virus to the biology of its host.…”

Section: Resultsmentioning

confidence: 99%

“…A colony was established, which reached 15,000 females by July 2000 but experienced a steady decline in 2001 and was lost by 2002. Efforts to identify the cause(s) of the decline led to the discovery of a high proportion (over 85% in some samples) of male and female individuals with salivary gland hypertrophy (SGH), a syndrome first described in wild populations of G. pallidipes (12,80) but later observed in many tsetse fly species from different African countries (17,24,38,39,48,50,54,65). The causative agent of this syndrome was later identified as a nuclear rod-shaped, enveloped DNA virus averaging 70 by 640 nm in size (33).…”

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confidence: 99%

“…This virus was also found to be associated with testicular degeneration and ovarian abnormalities (38,42,59,60), and its presence has been shown to affect the development, survival, fertility, and fecundity of naturally (20) or experimentally (40,62) infected flies. Mother-to-offspring transmission, either transovum or through infected milk glands (39,59,61), is thought to be the mode of transmission of the virus in natural tsetse fly populations. In reared colonies, however, horizontal transmission facilitated by the membrane feeding technique used for large-scale feeding of tsetse flies (21) may constitute the main route of virus transmission.…”

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confidence: 99%

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Genome Analysis of a Glossina pallidipes Salivary Gland Hypertrophy Virus Reveals a Novel, Large, Double-Stranded Circular DNA Virus

Abd-Alla

François

Parker

et al. 2008

J Virol

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Several species of tsetse flies can be infected by the Glossina pallidipes salivary gland hypertrophy virus (GpSGHV). Infection causes salivary gland hypertrophy and also significantly reduces the fecundity of the infected flies. To better understand the molecular basis underlying the pathogenesis of this unusual virus, we sequenced and analyzed its genome. The GpSGHV genome is a double-stranded circular DNA molecule of 190,032 bp containing 160 nonoverlapping open reading frames (ORFs), which are distributed equally on both strands with a gene density of one per 1.2 kb. It has a high A؉T content of 72%. About 3% of the GpSGHV genome is composed of 15 sequence repeats, distributed throughout the genome. Although sharing the same morphological features (enveloped rod-shaped nucleocapsid) as baculoviruses, nudiviruses, and nimaviruses, analysis of its genome revealed that GpSGHV differs significantly from these viruses at the level of its genes. Sequence comparisons indicated that only 23% of GpSGHV genes displayed moderate homologies to genes from other invertebrate viruses, principally baculoviruses and entomopoxviruses. Most strikingly, the GpS-GHV genome encodes homologues to the four baculoviral per os infectivity factors (p74 [pif-0], pif-1, pif-2, and pif-3). The DNA polymerase encoded by GpSGHV is of type B and appears to be phylogenetically distant from all DNA polymerases encoded by large double-stranded DNA viruses. The majority of the remaining ORFs could not be assigned by sequence comparison. Furthermore, no homologues to DNA-dependent RNA polymerase subunits were detected. Taken together, these data indicate that GpSGHV is the prototype member of a novel group of insect viruses.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Genome Analysis of a Glossina pallidipes Salivary Gland Hypertrophy Virus Reveals a Novel, Large, Double-Stranded Circular DNA Virus

Abd-Alla

François

Parker

et al. 2008

J Virol

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“…The vertical transmission is subdivided into two forms: transovarial and transovum, in which the parasites are present within the eggs or on the eggshells, respectively [20], [23], [24]. In the latter scenario, the parasites are acquired by the newly hatched nymphs or larvae by feeding on eggshell remnants [24].…”

Section: Introductionmentioning

confidence: 99%

Transovum Transmission of Trypanosomatid Cysts in the Milkweed Bug, Oncopeltus fasciatus

Dias

Vasconcellos²,

Romeiro³

et al. 2014

PLoS ONE

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Leptomonas wallacei is a trypanosomatid that develops promastigotes and cystic forms in the gut of the hemipteran insect Oncopeltus fasciatus. Insect trypanosomatids are thought to be solely transmitted from one host to another through the ingestion of parasite-contaminated feces. However, here we show that L. wallacei cysts present on the eggshells of eggs laid by O. fasciatus can also act as infective forms that are transmitted to the insect offspring. Newly hatched O. faciatus nymphs are parasite-free, but some of them become contaminated with L. wallacei after feeding on eggshell remnants. The present study is the first report of transovum transmission of a trypanosomatid, a process that may have a relevant role in parasite’s within-host population dynamics.

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“…The tsetse SGHV was capable of infecting the male testes, causing azoospermia or oligospermia (11). Venereal transmission between infected and healthy tsetse flies has been reported (13).…”

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confidence: 99%

Effects of Salivary Gland Hypertrophy Virus on the Reproductive Behavior of the Housefly, Musca domestica

Lietze

Geden

Blackburn

et al. 2007

Appl Environ Microbiol

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Pathological studies demonstrated that the salivary gland hypertrophy virus of houseflies (MdSGHV) shuts down reproduction in infected females. The mechanism that underlay the disruption of reproduction functioned on several levels. Females infected at the previtellogenic stage did not produce eggs, reflecting a block in the gonadotropic cycle. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis of hemolymph samples demonstrated that MdSGHV infection reduced the levels of both the female-specific hexamerin and egg yolk proteins. Furthermore, reverse transcriptase quantitative real-time PCR data demonstrated that infection blocked hexamerin and yolk protein gene transcription. When females were allowed to develop eggs prior to infection (postvitellogenic stage), the outcome of mating attempts depended upon when mating took place. If egg-containing, virus-infected females were mated within 24 h of infection, they copulated and deposited a single batch of fertilized eggs. However, if mating was delayed for a longer period, the egg-containing females refused to copulate with healthy males. Both of these results suggested that a virusinduced signal influenced the central nervous system, shutting down female receptivity and egg production. All experiments demonstrated that MdSGHV-infected males did not display azoospermia and were fertile. Both healthy females mated with infected males, and the resulting F1 progeny were free of salivary gland hypertrophy symptoms, which suggests that the virus is not sexually or vertically transmitted.In the early 1990s, an insect virus was detected and isolated from hypertrophied salivary glands of male and female houseflies, Musca domestica L., in Florida. The virus was described initially as a nonoccluded, enveloped, rod-shaped, doublestranded DNA virus (7). Feeding bioassays demonstrated that the virus could be transmitted per os to healthy adult houseflies and that infection with the virus was responsible for the salivary gland hypertrophy (SGH) symptoms. In these experiments, 95% of the female houseflies with symptoms of SGH showed no sign of ovarian development (7). A similar virus causing symptoms of SGH has been reported in the narcissus bulb fly, Merodon equestris (Fabricius) (3), and in various species of tsetse flies, Glossina spp. (3, 11). Comparisons of the different virus-host fly systems have demonstrated that the different viruses have several morphological and pathological properties in common (3,7,8,11,15,16,19). Electron microscopic observation of virus particles either in thin sections of hypertrophied salivary glands or from sucrose density gradientpurified, negatively stained preparations showed enveloped bacilliform virions. In all three fly groups, the virus replicates in the salivary gland tissue of male and female flies. Additionally, infected adults do not exhibit any external disease symptoms, and morphogenesis occurs in the nuclei, resulting in nuclear SGH.The most thoroughly studied SGH viruses (SGHVs) are those associated...

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Ultrastructural evidence for trans-ovum transmission of the DNA virus of tsetse,Glossina pallidipes (Diptera: Glossinidae)

Cited by 34 publications

References 8 publications

Genome Analysis of a Glossina pallidipes Salivary Gland Hypertrophy Virus Reveals a Novel, Large, Double-Stranded Circular DNA Virus

Genome Analysis of a Glossina pallidipes Salivary Gland Hypertrophy Virus Reveals a Novel, Large, Double-Stranded Circular DNA Virus

Transovum Transmission of Trypanosomatid Cysts in the Milkweed Bug, Oncopeltus fasciatus

Effects of Salivary Gland Hypertrophy Virus on the Reproductive Behavior of the Housefly, Musca domestica

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