Plaque reduction neutralization test for measles antibodies: Description of a standardised laboratory method for use in immunogenicity studies of aerosol vaccination.
ABSTRACT Clinical trials of measles vaccination administered as aerosol are planned with the aim of obtaining licensure. Measles antibody levels will be measured using the plaque reduction neutralization test (PRNT) to assess antibody responses as a surrogate marker of efficacy.
A working group examined laboratory protocols for measles PRNT in use at three reference centres and agreed to a standardised procedure, which was subsequently validated.
Assay validation showed quantitative results varied approximately threefold both within and between assays. The lower limit of detection was approximately 20milliInternational Units/mL.
A standardised laboratory protocol for measles PRNT was established and validated for use in clinical trials of aerosolized measles vaccines.
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ABSTRACT: Aerosol immunization may be a useful tool to reach and sustain the elimination of measles, rubella, and congenital rubella syndrome. We compared booster seroresponses to aerosolized or injected MMR vaccines containing different strains of measles (Attenuvax or Edmonston-Zagreb) and mumps (Jeryl-Lynn or Leningrad-Zagreb).Vaccine 05/2014; 32(29). DOI:10.1016/j.vaccine.2014.04.031 · 3.49 Impact Factor
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ABSTRACT: West Nile virus (WNV) is a mosquito-borne flavivirus that causes subclinical symptoms, febrile illness with possible kidney infarction and encephalitis. Since WNV was first serologically detected in Assam during 2006, it has become recognized as an important etiological agent that causes acute encephalitis syndrome (AES) in addition to endemic Japanese encephalitis virus (JEV). Therefore, isolating and characterizing the currently circulating strain of WNV is important. The virus was isolated from the cerebrospinal fluid (CSF) of two patients that presented with AES. The genotyping of the isolates HQ246154 (WNIRGC07) and JQ037832 (WNIRTC08) based on the partial sequencing of 921 nucleotides (C-prM-E) of the genome placed them within lineage 5 along with other Indian strains isolated prior to 1982, but the present circulating virus formed a distinct subclade. The derived amino acid sequence alignment indicated substitution in A81T and A84P of the capsid region in HQ246154. A cross-neutralization assay suggested substantial antigenic variation between isolates. The pathogenesis in mice that suggested the circulating WNV was neuroinvasive and comparatively more pathogenic than previous strains from India.Comparative immunology, microbiology and infectious diseases 11/2013; 37(1). DOI:10.1016/j.cimid.2013.10.006 · 2.11 Impact Factor
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ABSTRACT: The kinetics of respiratory syncytial virus (RSV) neutralizing antibodies following birth, primary and secondary infections are poorly defined. The aims of the study were to measure and compare neutralizing antibody responses at different time points in a birth cohort followed-up over three RSV epidemics. Rural Kenyan children, recruited at birth between 2002 and 2003, were monitored for RSV infection over three epidemic seasons. Cord and 3-monthly sera, and acute and convalescent sera following RSV infection, were assayed in 28 children by plaque reduction neutralization test (PRNT). Relative to the neutralizing antibody titers of pre-exposure control sera (1.8 log10 PRNT), antibody titers following primary infection were (i) no different in sera collected between 0 and 0.4 months post-infection (1.9 log10 PRNT, P = 0.146), (ii) higher in sera collected between 0.5 and 0.9 (2.8 log10 PRNT, P < 0.0001), 1.0-1.9 (2.5 log10 PRNT, P < 0.0001), and 2.0-2.9 (2.3 log10 PRNT, P < 0.001) months post-infection, and (iii) no different in sera collected at between 3.0 and 3.9 months post-infection (2.0 log10 PRNT, P = 0.052). The early serum neutralizing response to secondary infection (3.02 log10 PRNT) was significantly greater than the early primary response (1.9 log10 PRNT, P < 0.0001). Variation in population-level virus transmission corresponded with changes in the mean cohort-level neutralizing titers. It is concluded that following primary RSV infection the neutralizing antibody response declines to pre-infection levels rapidly (∼3 months) which may facilitate repeat infection. The kinetics of the aggregate levels of acquired antibody reflect seasonal RSV occurrence, age, and infection history. J Med. Virol. 85:2020-2025, 2013. © 2013 Wiley Periodicals, Inc.Journal of Medical Virology 11/2013; 85(11):2020-5. DOI:10.1002/jmv.23696 · 2.22 Impact Factor