Showing papers by "Scott C. Weaver published in 1990"
TL;DR: Infection of the mosquito Culiseta melanura by eastern equine encephalomyelitis virus was examined using transmission electron microscopy and results were consistent with dissemination of virus from the posterior midgut to salivary glands via the hemolymph.
Abstract: Infection of the mosquito Culiseta melanura (Coquillett) by eastern equine encephalomyelitis virus was examined using transmission electron microscopy (TEM) of whole tagmata and fluorescent antibody assay (FA) and infectious assay (IA) of dissected tissues. Following infectious blood meals from chicks circulating different virus titers, mosquitoes were examined after extrinsic incubation intervals of 1-22 d. Virus was first detected by FA and IA in midguts and nonalimentary tissues 24 h after infection. Nascent virus was first visualized by TEM in several tissues, including midgut, fat body, and salivary glands, of high-titer-infected mosquitoes 48 h after they engorged. Moderate- and low-titer blood meals resulted in slightly slower appearance and dissemination of virus. Results were consistent with dissemination of virus from the posterior midgut to salivary glands via the hemolymph. Neural tissues contained little or no virus, whereas fat body appeared to be an important organ for virus replication and dissemination. Dissemination barriers did not accompany mosquito infections.
42 citations
Journal Article•
TL;DR: Assay of adult progeny from females that fed on viremic chicks and fluorescent antibody studies of infected females failed to provide evidence that EEE virus is transmitted vertically by Ae.
Abstract: We examined susceptibility of a strain of Aedes albopictus from Houston, Texas to experimental infection with eastern equine encephalomyelitis (EEE) virus. After 15 days of extrinsic incubation, all Ae. a!bopictu.q' examined by the cell culture assay and fluorescent antibody staining were infected but only 57 (4/7, of the mosquitoes that refed transmitted virus bv bite. Data supported the concept of a salivary gland infection barrier to EEE virus in Ae. aIbopicms and the conclusion that virus replicates in fat body following dissemination from the midguand prior to infection of salivary glands. Assay of adult progeny from females that fed on viremic chicks and fluorescent antibody studies of infected females failed to provide evidence that EEE virus is transmitted vertically by Ae. albopictus.
24 citations
TL;DR: Midguts of the mosquito Culiseta melanura (Coquillett) were examined by light and electron microscopy at varying intervals after blood feeding to find cell loss was apparently low in the abdominal midgut, with occasional cellular debris detected in the lumen 3-5 d after engorgement.
Abstract: Midguts of the mosquito Culiseta melanura (Coquillett) were examined by light and electron microscopy at varying intervals after blood feeding. Peritrophic membrane deposition first appeared 6 h after engorgement as a thin, electron-translucent band adjacent to epithelial cells throughout the abdominal midgut and reached maximum thickness at 12 h. Cell loss was apparently low in the abdominal midgut, with occasional cellular debris detected in the lumen 3–5 d after engorgement. Sloughing of cytoplasmic dropletlike evaginations, devoid of organelles, occurred infrequently in the abdominal midgut between 5 and 7 d after feeding. In contrast, cellular and cytoplasmic loss occurred continuously in the thoracic midgut. Epithelial cell replacement and regenerative cell mitosis were not detected in the abdominal or thoracic midgut.
16 citations
TL;DR: Evidence was obtained that myelin-like material in the lysosomes, probably the result of mitochondrial autolysis, is extruded into the lumen of the mosquito, Culiseta melanura.
Abstract: Abdominal midguts of the mosquito, Culiseta melanura, were examined by light and electron microscopy 1 hr-14 days days after blood feeding. Epithelial cells were drastically altered from columnar to squamous in form after engorgement, and returned to columnar by day 4 after feeding. Accumulation of mitochondria along brush borders of digestive cells, followed by the appearance of large secondary lysosomes, accompanied blood digestion. Evidence was obtained that myelin-like material in the lysosomes, probably the result of mitochondrial autolysis, is extruded into the lumen. Digestive cells resumed their pre-blood meal appearance by 10-14 days post-engorgement. Regenerative cells were scattered throughout the basal portion of the epithelium, along with endocrine cells. Other midgut cells containing large, microvilli-lined apical cavities were identified in most specimens. No evidence of division or differentiation was obtained for any cell types.
13 citations