Home About us Contact
|
Home About us Contact | ||
|
|
||
Virus Shedding (virus + shedding)
Selected AbstractsInfluenza A viruses with truncated NS1 as modified live virus vaccines: Pilot studies of safety and efficacy in horsesEQUINE VETERINARY JOURNAL, Issue 1 2009T. M. Chambers Summary Reasons for performing study: Three previously described NS1 mutant equine influenza viruses encoding carboxyterminally truncated NS1 proteins are impaired in their ability to inhibit type I IFN production in vitro and are replication attenuated, and thus are candidates for use as a modified live influenza virus vaccine in the horse. Hypothesis: One or more of these mutant viruses is safe when administered to horses, and recipient horses when challenged with wild-type influenza have reduced physiological and virological correlates of disease. Methods: Vaccination and challenge studies were done in horses, with measurement of pyrexia, clinical signs, virus shedding and systemic proinflammatory cytokines. Results: Aerosol or intranasal inoculation of horses with the viruses produced no adverse effects. Seronegative horses inoculated with the NS1-73 and NS1-126 viruses, but not the NS1-99 virus, shed detectable virus and generated significant levels of antibodies. Following challenge with wild-type influenza, horses vaccinated with NS1-126 virus did not develop fever (>38.5°C), had significantly fewer clinical signs of illness and significantly reduced quantities of virus excreted for a shorter duration post challenge compared to unvaccinated controls. Mean levels of proinflammatory cytokines IL-1, and IL-6 were significantly higher in control animals, and were positively correlated with peak viral shedding and pyrexia on Day +2 post challenge. Conclusion and clinical relevance: These data suggest that the recombinant NS1 viruses are safe and effective as modified live virus vaccines against equine influenza. This type of reverse genetics-based vaccine can be easily updated by exchanging viral surface antigens to combat the problem of antigenic drift in influenza viruses. [source] Efficacy of a live equine herpesvirus-1 (EHV-1) strain C147 vaccine in foals with maternally-derived antibody: protection against EHV-1 infectionEQUINE VETERINARY JOURNAL, Issue 5 2004J. R. PATEL Summary Reasons for performing study: Currently, there is no recommended immunoprophylaxis against febrile respiratory diseases due to equine herpesvirus-1 (EHV-1) and -4 (EHV-4) in horses below age 5,6 months. This is because of interference by maternally-derived antibody (MDA) of vaccines. Objective: Unweaned equine foals are an important reservoir of EHV-1 transmission; therefore, we experimentally assessed the efficacy of a live EHV-1 vaccine in foals age 1.4-3.5 months with MDA. Methods: Following vaccination and challenge, parameters assessed were virus shedding in nasal mucus, leucocyte-associated viraemia, circulating virus neutralising antibody activity and clinical reactions. Results: Controlled challenge showed that a single intranasal dose of the vaccine afforded partial but significant protection against febrile respiratory disease, virus shedding and viraemia due to EHV-1 infection, despite virus-neutralising MDA. Conclusions and potential relevance: The prospective vaccine would be a significant step forward in reducing the incidence of the disease caused by EHV-1 infection. [source] Comparison of viral load and duration of virus shedding in symptomatic and asymptomatic neonatal rotavirus infectionsJOURNAL OF MEDICAL VIROLOGY, Issue 10 2010Sasirekha Ramani Abstract A single rotavirus strain causing asymptomatic infections as well as severe gastrointestinal disease has been described in the neonatal nurseries of the Christian Medical College, Vellore. In this study, quantitative real-time RT-PCR was used to determine the association of viral load with the presence of gastrointestinal symptoms in neonates. Viral load was estimated in terms of the crossing point [C(t) value] at which the amplicon could be detected in the real-time PCR assay. The study was carried out on 103 neonates, including 33 asymptomatic neonates and 70 neonates with different gastrointestinal symptoms. The duration of virus shedding was also compared between five symptomatic and four asymptomatic neonates using real-time RT-PCR. There was no significant difference in viral load between symptomatic and asymptomatic neonates (P,=,0.087). Among neonates with different gastrointestinal symptoms, those presenting with feed intolerance and abdominal distension had a significantly higher viral load than those with other gastrointestinal symptoms (P,=,0.02). For the study on virus shedding, nine neonates were followed up for a median duration of 53 days, with a median of 31 samples tested per child. Extended shedding of low copies of rotavirus was found, with no significant differences in pattern of shedding between symptomatic and asymptomatic neonates. The lack of correlation between viral load and gastrointestinal disease demonstrates yet another difference between neonatal rotavirus infection and infection in older children where higher viral load correlates with severe disease. J. Med. Virol. 82:1803,1807, 2010. © 2010 Wiley-Liss, Inc. [source] Human cytomegalovirus-associated oral and maxillo-facial diseaseCLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2007S. Doumas Abstract Human cytomegalovirus is a ubiquitous pathogen with protean clinical manifestations. After initial infection, the virus remains in a persistent state in the host. Immunity plays a pivotal role in counteracting its virulence, albeit intermittent virus shedding occurs in immunocompetent individuals. Should deficiencies in immunity occur, e.g., as a consequence of AIDS or iatrogenic immunosuppression, then virus replication and subsequent pathogenic manifestations ensue. In the oral and maxillo-facial region, the virus causes a wide variety of diseases, mainly atypical chronic ulcerations and sialadenitis. These morbidities are rarely reported and sometimes cause significant problems for clinicians. [source] | ||||||||||