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At least 19 recordsLinked to original sources
PubMed2024

Age and gender profiles of HIV infection burden and viraemia: novel metrics for HIV epidemic control in African populations with high antiretroviral therapy coverage.

INTRODUCTION: To prioritize and tailor interventions for ending AIDS by 2030 in Africa, it is important to characterize the population groups in which HIV viraemia is concentrating. METHODS: We analysed HIV testing and viral load data collected between 2013-2019 from the open, population-based Rakai Community Cohort Study (RCCS) in Uganda, to estimate HIV seroprevalence and population viral suppression over time by gender, one-year age bands and residence in inland and fishing communities. All estimates were standardized to the underlying source population using census data. We then assessed 95-95-95 targets in their ability to identify the populations in which viraemia concentrates. RESULTS: Following the implementation of Universal Test and Treat, the proportion of individuals with viraemia decreased from 4.9% (4.6%-5.3%) in 2013 to 1.9% (1.7%-2.2%) in 2019 in inland communities and from 19.1% (18.0%-20.4%) in 2013 to 4.7% (4.0%-5.5%) in 2019 in fishing communities. Viraemia did not concentrate in the age and gender groups furthest from achieving 95-95-95 targets. Instead, in both inland and fishing communities, women aged 25-29 and men aged 30-34 were the 5-year age groups that contributed most to population-level viraemia in 2019, despite these groups being close to or had already achieved 95-95-95 targets. CONCLUSIONS: The 95-95-95 targets provide a useful benchmark for monitoring progress towards HIV epidemic control, but do not contextualize underlying population structures and so may direct interventions towards groups that represent a marginal fraction of the population with viraemia.

Universal Test and Treat↗
PubMed1979

Viraemia in Clethrionomys glareolus -- a new ecological marker of tick-borne encephalitis virus.

Viraemia was studied in adult Clethrionomys glareolus subcutaneously infected with 12 strains of tick-borne encephalitis (TBE) virus isolated in western and eastern foci of TBE. Nine strains caused viraemia regularly or irregularly, reaching titres higher than the threshold level of TBE virus infectivity for its vectors, ixodid ticks (2.5 -- 4.5 log LD50/0,03 ml) and three strains caused lower levels of hiraemia (0.4 -- 1.5 log LD50/0.03 ml). The ability or inability of various TBE virus strains to cause viraemia in adult C. glareolus in titres higher than the threshold level of infectivity for tick vectors was considered as an ecological marker of TBE virus. This marker was designated Cg: Cg+ and Cg- for TBE virus strains inducing respectively higher and lower levels of viraemia than the threshold of infectivity.

Animals↗
PubMed1978

The pathogenesis of infectious avian encephalomyelitis. 3. The relationship between viraemia, invasion of the brain by the virus, and the development of specific serum neutralising antibody.

An association was demonstrated between the development of clinical infectious avian encephalomyelitis (IAE), the persistence and titre of infectious avian encephalomyelitis virus (IAEV) in the brain of the chicken, the duration of detectable viraemia and the age of the chicken at the time of infection with the virus. The older the chicken at the time of infection the milder the disease, the lower the virus titre in the brain and the shorter the period of viraemia. IAEV serum neutralising antibody was produced earlier after infection in older chickens, and its detection was associated with decreasing virus titres in the brain and the cessation of detectable viraemia. Treatment of chickens with testosterone in ova, to inhibit the development of antibody synthesis, prevented the onset of age-associated resistance and testosterone treated birds were as susceptible to clinical IAE as baby chickens. The results suggested that the ability to produce IAEV serum neutralising antibody was an important component of age-associated resistance to IAE.

Age Factors↗
PubMed1978

Herpes virus of turkey vaccine: viraemias in field flocks and in experimental chickens.

In a field survey of viraemias due to vaccination of chickens with herpes virus of turkey, variation was encountered in titres and percentages of birds viraemic. The incidence of viraemias was much lower in sick than in healthy birds in flocks undergoing mortality from Marek's disease. In a concurrent experiment the same strain of chicken and the same commercial vaccine were used as in the field flocks affected with Marek's disease. A high incidence of viraemia and 84.6 per cent protection against Marek's disease were obtained with single vaccination at one day of age. Revaccination at 21 days of age produced no measurable benefits in the same experiment.

Age Factors↗
PubMed1976

Pathogenesis of foot-and-mouth disease: clearance of the virus from the circulation of cattle and goats during experimental viraemia.

Viraemia is an important aspect of the pathogenesis of infectious diseases, but the mechanisms of entry and removal of virus from the vascular system particularly in natural hosts are poorly understood. The results of this study showed that the clearance of foot and mouth disease virus (FMDV) from the circulation of cattle and goats followed the general rules for the clearance of inert particulate materials and other viruses from the circulation. High doses of infused FMDV were cleared less efficiently than low doses, probably as a result of a depletion of the reticulo-endothelial system by the higher doses. FMDV was cleared from the circulation of cattle at a considerably slower rate than from the circulation of goats, but in both species significant individual variation in clearance was observed. These results could explain individual as well as species variations relative to the onset and duration of viraemia.

Animals↗
PubMed1979

Investigation of the incidence of influenza A viraemia caused by virus strains circulating among children in 1968 - 1977.

Nineteen strains of Type A influenza virus isolated from the blood of small children in 1968--77 were studied. The investigation of the strains in HAIR with antisera to the antigenic components of the strains in HAIR with antisera to the antigenic components of the strains A/Hong-Kong/68,A/Anglia/72, A/Port Chalmers/73 and A/Victoria/75 made it possible to demonstrate antigenic "drive" of the haemagglutinin in the years 1968--1977 and to divide the strains into 4 varieties. A high sensitivity to inhibitors was observed in all the strains isolated. The study of pathogenicity and toxicity of the strains revealed viraemia in the strains isolated during the 1972--1973 epidemic and the subsequent epidemics with the absence of pathogenicity and toxicity for white mice. Regular finding of viraemia coincided in time with increased thermostablty of the haemagglutnin in the strains under study.

Allergy and Immunology↗
PubMed1976

Latent herpetic infections following experimental viraemia.

The spectrum of tissues harbouring latent herpes simplex virus following intravenous inoculation of mice was defined by in vitro co-cultivation techniques. The virus could be detected in central and peripheral nervous systems (including adrenal medulla), but could not be found in any non-neural tissues. Spinal ganglia were the organs most commonly involved. The relationship of these findings to the natural history of herpetic infections is discussed.

Adrenal Glands↗
PubMed1975

The comparative sensitivity of sheep and chicken embryos to bluetongue virus and observations on viraemia in experimentally infected sheep.

The virus titre in sheep blood samples received from BT-suspected cases in the field was assayed in sheep and in chicken embryos. These infected blood samples represented 3 different BT virus types: 4, 10 and 16. Three identical experiments were performed, one with each of the 3 different virus types. Ten-fold dilutions of the infected blood samples were prepared and 1 ml of each blood dilution was inoculated IV into series of 10 to 12-month old susceptible sheep; at the same time 0.1 ml of each dilution was inoculated IV into series of 10 to 13-day-old chicken embryos. The virus titre was found to be similar when assayed in the two host systems. There was no correlation between the amount of virus inoculated and the severity of symptoms in the inoculated sheep. The virus content in daily blood samples collected from the experimental sheep was assayed by IV inoculation of CE. Virus was isolated from all the reacting sheep and was detected sometimes as early as 1 day PI and as late as 30 days PI. A high titre of log10 4.0 to 7.0 per 1 ml of blood was recorded during several consecutive days before and after the onset of clinical signs. There seemed to be an inverse ratio between the amount of virus inoculated and the number of days the virus persisted in the bloodstream. The neutralisation index in day 22 serum samples was 3.5 to 4.5. Virus was isolated from some of the reacting sheep on the day that these antibody levels were recorded. Since the comparative simultaneous titrations of BT virus in sheep and in CE yielded similar results, the IV inoculation of CE is advocated as the routine method to be employed for laboratory diagnosis of this disease.

Animals↗
PubMed1978

A cell culture vaccine against bovine ephemeral fever.

A vaccine was prepared from cell culture fluids harvested from the twelfth passage of the 919 strain of bovine ephemeral fever (BEF) virus in Vero cell cultures. Cattle were vaccinated subcutaneously with various combinations of strain 919 virus and adjuvants. Neutralising antibodies were assayed at various times after vaccination and some cattle were challenged by intravenous inoculation with the virulent 417WBC strain of BEF virus. Strain 919 virus of the third and twelfth passage levels in Vero cells produced neither fever, clinical illness nor detectable viraemia in 5 calves inoculated intravenously. Nor could viraemia be detected in 5 heifers receiving vaccine subcutaneously. When the vaccine was administered mixed with aluminium hydroxide adjuvant, the production of neutralising antibodies increased with an increase in the volume of vaccine from 2.5 ml to 10 ml and the response to 2 injections was significantly better than the response to a single injection. The neutralising antibody response was decreased when vaccine was diluted in phosphate buffered saline. The neutralising antibody response following 2 subcutaneous vaccinations with strain 919 virus mixed with aluminium hydroxide adjuvant was higher than that following intravenous inoculation with virulent virus. The vaccine-induced antibodies persisted for at least 12 months, and revaccination at this time led to an increase in the titre of neutralising antibody. Antibodies induced by a single subcutaneous administration of strain 919 virus mixed with Freund's complete adjuvant persisted for at least 40 weeks; those induced by vaccine containing Freund's incomplete adjuvant had virtually disappeared within 16 weeks. All these calves responded to vaccination with aluminium hydroxide-containing vaccine with increases in levels of neutralising antibodies. Of 26 vaccinated calves challenged with virulent BEF virus, 24 remained clinically normal. Two developed brief periods of pyrexia on the seventh day after challenge, but no other clinical signs. One of these calves had a viraemia that was demonstrated only by intravenous inoculation of a susceptible calf. The remaining calf had no detectable viraemia. All of 7 unvaccinated calves developed severe clinical BEF within 5 days of challenge. No disease attributable to the 919 virus occurred in 24 vaccinated pregnant heifers or their newborn calves.

Adjuvants, Immunologic↗
PubMed1976

Pathogenesis of foot-and-mouth disease: the lung as an additional portal of entry of the virus.

Donor cattle infected with foot and mouth disease (FMD) virus subtype O1 were used to expose experimental cattle. The pharyngeal virus growth and viraemia patterns after contact exposure were quite different from those obtained after intranasal inoculation and suggested that the lower respiratory tract might provide an additional portal of entry for the virus. A tracheotomy was performed on experimental cattle to let the respiration bypass the pharynx, followed by exposure to FMD virus by different routes. The results confirmed that FMD virus can enter the bloodstream via the lung, followed by haematogenic infection of the pharynx and other replication sites simultaneously. These observations led to further experiments in which the intravenous route of infection was used to study the interaction of virus growth in the phayrnx, in other sites, and in viraemia.

Aerosols↗