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Biomedical subjects

R B Tesh

Publications and source records attributed to R B Tesh.

At least 145 records · Page 8Linked to original sources
PubMed1979

Transovarial transmission of yellow fever virus by mosquitoes (Aedes aegypti).

Female Aedes aegypti mosquitoes infected with yellow fever virus by intrathoracic inoculation transmitted the virus to a small percentage of their F1 progeny. Infected offspring were obtained from surface-sterilized as well as from untreated eggs, indicating that the virus was transovarially transmitted. Vertical transmission of yellow fever virus in mosquitoes may be an alternative mechanism for biological survival of the virus during adverse periods or in the absence of susceptible vertebrate hosts.

Aedes↗
PubMed1979

Antigenic variation among strains of the New Jersey serotype of vesicular stomatitis virus.

Four strains of vesicular stomatitis virus--New Jersey (Hazelhurst, Guatemala, Panama, and Concan) were compared by cross-neutralization and complement-fixation tests. They were indistinguishable by complement-fixation test; however, by plaque-reduction neutralization method, slight antigenic differences were observed between the Hazelhurst and the three other strains. It is concluded that these antigenic differences are insufficient to warrant reclassification of vesicular stomatitis virus--New Jersey into two distinct subtypes, as has been recently proposed.

Animals↗
PubMed1978

Transovarial transmission of Japanese encephalitis virus by mosquitoes.

Female Aedes albopictus and Aedes togoi mosquitoes infected with Japanese encephalitis virus either by intrathoracic inoculation or by ingestion of a virus-sucrose-erythrocyte mixture transmitted the virus to a small percentage of their F1 progeny. Adult F1 female Aedes albopictus thus infected transmitted the virus in turn to newly hatched chickens by feeding on them.

Aedes↗
PubMed1978

The prevalence of encephalomyocarditis virus neutralizing antibodies among various human populations.

The prevalence of encephalomyocarditis virus (EMC) antibodies among selected human populations in various regions of the world was determined by the plaque reduction neutralization method. Antibody rates among children ranged from 1.0 to 33.9%, while those among adults varied from 3.2 to 50.6%. No differences between sexes were found in the frequency of EMC infection. The pattern of age-specific antibody rates observed among the study populations suggests that EMC infection occurs primarily during childhood. There appeared to be no association between the presence of EMC antibodies and potential exposure to rats. Sera from diabetic, suspected encephalitis, and myocarditis patients were also examined for EMC neutralizing antibodies. The prevalence of antibodies among these groups was not significantly different from that of control populations in the same geographic regions. No association was demonstrated between EMC infection and these three diseases. The results of this study indicate that EMC infection in man is fairly common but that most human cases are probably asymptomatic and/or unrecognized.

Adolescent↗
PubMed1977

Effect of insecticide spraying for malaria control on the incidence of sandfly fever in Athens, Greece.

Sera from 637 Athens residents of various age groups were examined by plaque reduction neutralization test for antibodies against Naples and Sicilian Phlebotomus fever viruses. A marked change in the prevalence of antibodies to both agents was observed in persons born after 1946, when residual insecticide spraying for malaria control was initiated in Greece. The prevalence of Naples and Sicilian neutralizing antibodies among residents greater than or equal to 30 years of age was 36% and 13%, respectively. In contrast, only 4% of persons less than or equal to 29 years of age had Naples antibodies and all were negative to Sicilian. These serologic data confirm previous clinical observations that sandfly fever becam uncommon in Athens after initiation of the insecticide spraying program. Presumedly the spraying program was effective in reducing the Phlebotomus population to levels where virus transmission was minimal. New information on the specificity and duration of Phlebotomus fever neutralizing antibodies is also presented.

Adolescent↗
PubMed1976

Variation among goegraphic strains of Aedes albopictus in susceptibility to infection with chikungunya virus.

Two types of variation were observed when the susceptibility of 16 different geographic strains of Aedes albopictus to oral infection with chikungunya (CHIK) virus was studied. One was differential susceptibility to infection with the virus. The other was variation in the quantity of virus present in infected mosquitoes after a standard incubation period. Mean virus titers of infected mosquitoes of different geographic strains varied almost 1,000-fold. Attempts to develop increasingly resistant or susceptible mosquito lines through genetic selection were unsuccessful. Infection rates did not change significantly despite 3 to 6 generations of selective inbreeding. In contrast, crosses between strains of high and low CHIK susceptibility yielded hybrid mosquitoes with infection rates and mean virus titers intermediate between those of the parent colonies. These data suggest that at least one factor controlling the susceptibility of A. albopictus to CHIK infection is genetic. Two lines of A. albopictus with a marked difference in susceptibility to oral infection with dengue viruses were equally susceptible to oral infection with chikungunya virus.

Aedes↗
PubMed1976

Clinical and serologic responses of volunteers infected with phlebotomus fever virus (Sicilian type).

Twenty volunteers were inoculated with various doses of human serum containing Phlebotomus fever virus (Sicilian type) to determine their clinical and serologic responses as well as the human infectious dose50 of the virus. All infected subjects developed fever which varied in duration from 6 to 74 hours. The most common symptoms during sandfly fever were headache, anorexia, myalgia, photophobia, low back and retro-orbital pain. Infected individuals developed a marked leukopenia characterized by an initial lymphopenia followed by protracted neutropenia. Little complement fixing antibody was detected in convalescent sera but most subjects developed significant rises in hemagglutination inhibiting antibodies. All infected subjects developed specific neutralizing antibodies with titers ranging from 1:40 to 1:2,560. Of the three serologic tests performed, the plaque reduction neutralization method appears to be the most sensitive test for detecting antibodies to Phlebotomus fever viruses.

Adult↗
PubMed1976

Serological studies on the epidemiology of sandfly fever in the Old World.

Selected human sera from 59 different localities in Africa, the Mediterranean littoral, eastern Europe and Asia were examined by plaque reduction neutralization test against eight sandfly (Phlebotomus) fever virus serotypes (Sicilian, Naples, Arumowot, SudAn 754-61, Karimabad, Salehabad, Gordil and Saint Floris) known to occur in the Old World. Results of these studies provide new information on the geographic distribution and prevalence of human infection with each of the viruses. Specific neutralizing antibodies were detected against all of the agents except Salehabad. Naples and Sicilian antibodies were encountered most frequently and had the widest geographic range; moreover they were found only in areas where Phlebotomus papatasi occurs. Age-specific antibody rates for several of the viruses are presented. These data and the epidemiology of sandfly fever are discussed.

Adolescent↗
PubMed1975

Failure of rubella virus to replicate in mosquitos.

Rubella virus failed to replicate in mosquitoes (Aedes albopictus and Culex fatigans) following parenteral inoculation. The virus demonstrated in mosquitoes tested immediately after inoculation but was not detected in insects sampled 7, 14 and 21 days postinoculation. This experiment provides further evidence that rubella is not an arbovirus, but does not invalidate its classification as a togavirus.

Aedes↗
PubMed1975

Antigenic relationships among phlebotomus fever group arboviruses and their implication for the epidemiology of sandfly fever.

The antigenic relationships of 21 known or presumed Phlebotomus fever group serotypes and of 2 ungrouped, solvent sensitive, sandfly-associated arboviruses (Pacui and Charleville) were studied by complement fixation, plaque neutralization, and hemagglutination-inhibition methods. Results of complement fixation and neutralization tests were specific, allowing clear separation of the various serotypes, while those of the hemagglutination-inhibition test showed broader crossing and lack of specificity. Pacui virus was shown to be a member of the Phlebotomus fever serogroup. Six new Phlebotomus fever group serotypes are also described, increasing the known members of the group to 22. The implications of these and other recent data about the epidemiology of sandfly fever are discussed.

Animals↗
PubMed1975

The distribution and prevalence of group A arbovirus neutralizing antibodies among human populations in Southeast Asia and the Pacific islands.

Plaque reduction neutralization tests, using five group A arboviruses (chikungunya, Ross River, Getah, Bebaru and Sindbis), were done on sera from human populations in 44 Southeast Asia and Pacific island localities. Specificity of the plaque neutralization test was determined by examining convalescent sera from patients with known alphavirus infections. Chikungunya-specific neutralizing antibodies were demonstrated in sera of persons living in South Vietnam, Northern Malaysia, Indonesia (Kalimantan and Sulawesi), as well as Luzon, Marinduque, Cebu and Mindanao islands in the Philippines. Evidence of Ross River virus infection was found among populations living in West New Guinea and Papua New Guinea mainland, the Bismark Archipelago, Rossel Island and the Solomon Islands. There appeared to be no geographic overlap in the distribution of chikungunya and Ross River viruses, with the separation in their distribution corresponding with Weber's line in the Pacific. Sindbis neutralizing antibodies were found in 7 of 21 populations sampled, but in general the prevalence of infection was low. Four sera, from Vietnam, Malaysia and Mindanao gave monospecific reactions with Getah virus. No evidence of specific Bebaru virus infection was detected. The epidemiology of these five alphaviruses in Southeast Asia and the Pacific islands is discussed.

Adolescent↗
PubMed1975

Laboratory studies of transovarial transmission of La Crosse and other arboviruses by Aedes albopictus and Culex fatigans.

Transovarial transmission of La Crosse virus by experimentally infected Aedes albopictus females to 2.7% of their F1 generation offspring was demonstrated. Progeny of both sexes were infected. Mean virus titers in parent mosquitoes and infected F1 generation adults were 10(4.6) and 10(3.4) plaque forming units/insect, respectively. The La Crosse-infected offspring were randomly distributed among the female parents. After two serial passages in A. albopictus, a marked change occurred in the plaque morphology of the virus but this had no apparent effect on the subsequent vertical transmission rate. In contrast, transovarial transmission did not occur in La Crosse-infected Culex fatigans or in A. albopictus and C. fatigans infected with vesicular stomatitis-Indiana, Cache Valley, Batai, Arumowot, and Itaporanga viruses. Results of this experiment suggest that the La Crosse model might be useful in studying the mechanism of transovarial transmission in additional mosquito species.

Aedes↗