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Biomedical subjects

M Fekadu

Publications and source records attributed to M Fekadu.

At least 37 records · Page 2Linked to original sources
PubMed1991

Oral vaccination of skunks with raccoon poxvirus recombinants expressing the rabies glycoprotein or the nucleoprotein.

Twenty nine skunks (Mephitis mephitis) were vaccinated orally with raccoon poxvirus (RCN) recombinants: 10 with a recombinant expressing the rabies virus glycoprotein (RCNRG), 10 with RCNRG mixed with a recombinant expressing the rabies virus nucleoprotein (RCNRN) and nine with RCN alone. Rabies virus neutralizing antibodies were detected in six of the 20 skunks; five skunks (three given RCNRG, two given a mixture of recombinants) survived a rabies challenge that was lethal for nine skunks vaccinated with RCN alone.

Administration, Oral↗
PubMed1990

Rabies diagnostic reagents prepared from a rabies N gene recombinant expressed in baculovirus.

A gene encoding the nucleoprotein (N) of rabies virus was inserted into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus. Recombinant gene expression was controlled by the strong polyhedrin gene promoter. Insect cells (Spodoptera frugiperda) infected by a baculovirus recombinant containing the rabies virus N gene produced abundant amounts of a novel 55-kilodalton protein of a size comparable to that of the rabies virus N protein, as demonstrated by polyacrylamide gel electrophoresis. This new gene product possessed the antigenic and immunogenic properties of native viral N protein, as shown by the ability of the new protein to react in immunoprecipitation and immunofluorescence assays with antirabies antibodies, to serve as a substitute for infectious rabies virus in adsorbing suspensions for diagnostic tests, and to induce high-titered antiserum. The baculovirus expression system provides a safe, convenient, and inexpensive source of rabies virus N protein for the production of both antiserum and adsorbing suspensions for use in rabies diagnoses.

Animals↗
PubMed1988

Pathogenesis of rabies virus from a Danish bat (Eptesicus serotinus): neuronal changes suggestive of spongiosis.

Rabies virus strains isolated from a European bat (Eptesicus serotinus) in Denmark (DBV), a North American big brown bat (Eptesicus fuscus) in New York State (NY-bat), and a human in South Africa (Duvenhage strain (DUV-1) were studied by using a panel of monoclonal antibodies and by inoculating mice, cats, and dogs. The ten Danish virus isolates from the same bat species reacted identically with a panel of monoclonal antibodies. Immunofluorescence, monoclonal antibody, and histopathologic studies showed that the Danish bat isolates were similar to Duvenhage, and to some degree, to classical rabies virus. All isolates produced fatal infections in mice when inoculated by the intracerebral, footpad, and oral routes. Dogs and cats inoculated intracerebrally with the DBV and DUV-1 virus strains died of rabies-like illnesses within 10 days. Although no dogs that were inoculated intramuscularly or intravenously showed signs of disease, all developed neutralizing antibodies and resisted challenge with lethal dose of street rabies virus. All dogs inoculated with the NY-bat virus, with the exception of those inoculated intravenously, showed classical signs of rabies and one of the intramuscularly inoculated dogs recovered. Cats inoculated intramuscularly also died of rabies-like illness within 15 days. At necropsy, rabies antigen was detected by immunofluorescence in frozen sections of several organs, including brain and salivary glands. Histopathologic and electron microscopic studies of the central nervous system of mice, dogs and cats that died of DBV infection showed neuronal cytoplasmic changes considered to be a form of spongiosis.

Animals↗
PubMed1988

Use of the avidin-biotin peroxidase system to detect rabies antigen in formalin-fixed paraffin-embedded tissues.

We stained rabies-infected nervous and salivary-gland tissues fixed in formalin or acetone and embedded in paraffin with the avidin-biotin peroxidase system. With this system, rabies-virus antigen was detected in neurons, glandular acinar cells, and vascular endothelial cells more effectively than by immunofluorescence, especially when tissues were enzyme-digested with pronase before immunoperoxidase staining. The avidin-biotin peroxidase system should be useful for routine diagnosis, retrospective studies of rabies, and identification of specific cells involved in the spread of virus in rabies-infected hosts.

Animals↗
PubMed1988

Efficacy of rabies vaccines against Duvenhage virus isolated from European house bats (Eptesicus serotinus), classic rabies and rabies-related viruses.

Isolates of rabies from separate enzootics can be distinguished by their reactions with panels of monoclonal antibodies (mAbs) directed to different sites on the nucleocapsid and glycoproteins of the virus. Estimates of antigenic relatedness can be made by comparing similarities among groups. In this manner it can be shown that while classic strains of rabies react with most of the mAbs, the rabies related Lyssaviruses (Mokola, Lagos and Duvenhage) react with only a few of the mAbs and isolates of rabies from Eptesicus serotinus bats in Europe are intermediate between the two groups. Mice immunized intraperitoneally with human diploid vaccine (HDCV) or animal vaccines (Rabisin and Rabiffa) were protected against a challenge with DBV, DUV-1 and most classic rabies strains. HDCV gave only partial protection against human virus isolates from Finland and Saudi Arabia. The HDCV did not protect mice against challenges with Lagos bat or Mokola virus (rabies-like viruses). The animal vaccines, however, did protect mice against Lagos bat virus, but not against Mokola. Dogs immunized with Rabisin were protected against an intracerebral challenge with DBV. Dogs developed rabies-neutralizing antibody titres after intramuscular or intravenous inoculation with live DBV or DUV-1 virus; these dogs were protected against an intramuscular canine street rabies virus challenge. We conclude that the rabies vaccines tested protect against DBV/DUV-1 and classic street rabies strains, but not Mokola.

Animals↗
PubMed1984

Peripheral distribution of virus in dogs inoculated with two strains of rabies virus.

Forty-seven Beagles were inoculated IM with an Ethiopian strain or a Mexican strain of rabies virus to study the pathogenesis of street rabies virus in dogs. Thirty-nine dogs died of rabies, with incubation periods lasting 9 to 69 days. Of the dogs that died, 82% had shown typical signs of rabies, but 18% died without any noticeable signs of illness. Eight dogs that remained healthy during an observation period lasting more than 2 years did not produce detectable amounts of rabies virus-neutralizing antibodies; however, when challenge exposed with a large dose of the homologous rabies virus inoculum, these 8 dogs responded with high antibody titers, but challenge-exposed control dogs died of rabies. Infective virus was isolated from the saliva and cerebrospinal fluid of dogs before any signs of rabies were noticed; rabies virus-neutralizing antibodies were not detected in the serum and cerebrospinal fluid before illness. In this study, viral antigen was not detected in the skin biopsy specimens taken before signs of rabies were noticed. At necropsy of the 39 dogs, rabies virus was detected in most tissues examined. Viral antigen was detected in the skin tissues of 14 (36.8%) of the 38 dogs examined. The presence of viral antigen in the skin seemed to correlate with the presence of virus in the salivary glands, but virus in the salivary glands did not indicate the presence of virus in the skin. Eleven (44%) of the 25 dogs which had virus in the salivary glands did not have any detectable amount of viral antigen in the skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Rabies virus in the tonsils of a carrier dog.

A female dog, inoculated with a rabies isolate from the saliva of an apparently healthy Ethiopian dog, developed rabies but later recovered without supportive treatment. Rabies virus was isolated from the saliva collected 42, 169 and 305 days after recovery. Sixteen months after it recovered, the dog suddenly died after giving birth to two stillborn puppies. At necropsy, viral antigen could be detected in the tonsils and the brain tissue, but viable virus was isolated from the Palatine tonsils only.

Animals↗
PubMed1982

Pathogenesis of rabies in dogs inoculated with an Ethiopian rabies virus strain. Immunofluorescence, histologic and ultrastructural studies of the central nervous system.

Dogs were inoculated with either an Ethiopian of Mexican rabies virus strain. The distribution of viral antigen and lesions were studied by immunofluorescence, histologic and electron microscopic techniques. In all dogs inoculated with the Ethiopian rabies virus strain, tremendous whorls of filamentous fluorescing aggregates were observed throughout the brain; these were not observed in dogs inoculated with the Mexican virus. Lesions consisted on neuronal degeneration and neuronophagia, associated with large inclusion bodies and widespread inflammation in dogs inoculated with the Ethiopian isolate. All observed portions of the brain and spinal cord were affected. In general, lesions were much less severe with Mexican isolate. Occasional astrocytes were observed to have inclusions in dogs inoculated both with Ethiopian and Mexican strains. Most neurons examined electronmicroscopically showed signs of infection, varying from a small granular or finely fibrillar viral matrix to numerous matrices accompanied by prolific numbers of virus particles occupying much of the perikaryon. These were found in all dogs inoculated with the Ethiopian strain but were rare with the Mexican isolate. Viral budding occurred from membranes of the rough endoplasmic reticulum, outer lamella of the nuclear envelope, and rarely from the plasma membrane.

Animals↗
PubMed1982

Excretion of rabies virus in the saliva of dogs.

Thirty-nine dogs were injected intramuscularly with either an Ethiopian strain or a Mexican strain of rabies virus. The excretion of rabies virus in the saliva was studied before and during illness. Nine of 17 dogs that died after injection with the Ethiopian strain had virus in the submaxillary glands. Four of these dogs excreted virus in the saliva up to 13 days before signs of disease were observed. Sixteen of 22 dogs that died after injection with the Mexican strain had virus in the submaxillary glands. Eight of these dogs also excreted virus in the saliva up to seven days before signs of disease were observed. These findings indicate that rabid dogs may excrete virus in their saliva much earlier than previously reported.

Animals↗
PubMed1982

Rabies in Ethiopia.

Rabies is one of the most severe infectious diseases in Ethiopia, with many cases of the disease diagnosed in various parts of the country. The dog is the species most responsible for human exposure, with over 98% of the human cases and vaccinations due to the bite of rabid or suspected rabid dogs. Most of the treatments are due to stray dogs that bite, escape and are not available for observation. Most of the people who die of rabies are under 40 years of age, and among adults, the majority of these are males, suggesting that the close contact the young men have with dogs causes them to have a higher exposure rate and more deaths from rabies.

Adolescent↗
PubMed1981

Intermittent excretion of rabies virus in the saliva of a dog two and six months after it had recovered from experimental rabies.

A dog inoculated with a rabies virus isolate from the saliva of an apparently healthy Ethiopian dog was followed for more than 9 months. Saliva and blood specimens were collected three times weekly and cerebrospinal fluid weekly. Saliva samples collected on days 42 and 169 after the dog's recovery produced fatal rabies infections in mice inoculated intracerebrally.

Animals↗
PubMed1980

Recovery from clinical rabies of 2 dogs inoculated with a rabies virus strain from Ethiopia.

Two dogs, inoculated with a strain of rabies virus from Ethiopia, showed typical signs of rabies 8 days after inoculation. After 3 or 4 days with a deterioration in the physical condition, both animals began to recover, as shown by increased muscular movements, reaction to stimuli, awareness of surroundings, and attempts to rise. Both animals recovered completely, although 1 then died of Pseudomonas bacterial pneumonia. An increase in serum-neutralizing antibody and in CSF or brain-neutralizing antibody was noted in both animals. Such concentrations have been noted only in animals or persons that recovered from rabies.

Animals↗
PubMedDate not supplied

Pathogenesis of rabies virus infection in dogs.

Most dogs experimentally infected with street rabies virus showed clinical signs of rabies before death, but up to 18% of the dogs died without showing detectable signs of illness. In dogs showing signs, rabies was not invariably fatal. Up to 20% of dogs recovered without any supportive treatment. Some dogs inoculated with American (southern Texas) or Ethiopian canine street virus excreted virus in their saliva up to 14 days before signs appeared. There was no relation between the time of excretion of virus in the saliva and the titer of virus in the salivary glands at death. One dog that recovered from rabies intermittently excreted rabies virus in its saliva for a long time. The carrier state in rabies may play a significant role in the perpetuation and survival of the virus and may become a source for rabies outbreaks whenever a new generation of rabies susceptibles reaches critical density.

Animals↗