Duration of post-vaccination humoral immunity against yellow fever in children.

Introduction: Vaccination is the most important measure for prevention and control of yellow fever. It is recommended by the World Health Organization (WHO) for residents of endemic areas and travelers to risk areas. In 2013, the WHO discontinued the recommendation of booster doses every 10 years, indicating a single dose as sufficient for lifelong protection.

Heparin removal by ecteola-cellulose pre-treatment enables the use of plasma samples for accurate measurement of anti-Yellow fever virus neutralizing antibodies.

Technological innovations in vaccinology have recently contributed to bring about novel insights for the vaccine-induced immune response. While the current protocols that use peripheral blood samples may provide abundant data, a range of distinct components of whole blood samples are required and the different anticoagulant systems employed may impair some properties of the biological sample and interfere with functional assays. Although the interference of heparin in functional assays for viral neutralizing antibodies such as the functional plaque-reduction neutralization test (PRNT), considered the gold-standard method to assess and monitor the protective immunity induced by the Yellow fever virus (YFV) vaccine, has been well characterized, the development of pre-analytical treatments is still required for the establishment of optimized protocols.

Kinetic Study of Yellow Fever 17DD Viral Infection in Gallus gallus domesticus Embryos.

Yellow fever continues to be an important epidemiological problem in Africa and South America even though the disease can be controlled by vaccination. The vaccine has been produced since 1937 and is based on YFV 17DD chicken embryo infection. However, little is known about the histopathological background of virus infection and replication in this model.

Immunogenicity and safety of measles-mumps-rubella vaccine delivered by disposable-syringe jet injector in healthy Brazilian infants: a randomized non-inferiority study.

This study aimed to determine if immunogenicity to measles-mumps-rubella vaccine delivered to infants via a disposable-syringe jet injector (DSJI) was non-inferior to that administered by needle and syringe (NS). Vaccination safety was evaluated, as were the use, performance, and acceptability of each delivery method. The DSJI was the PharmaJet 2009 generation-1 device (G1) and the vaccine was measles-mumps-rubella vaccine from Bio-Manguinhos.

17DD and 17D-213/77 yellow fever substrains trigger a balanced cytokine profile in primary vaccinated children.

Background: This study aimed to compare the cytokine-mediated immune response in children submitted to primary vaccination with the YF-17D-213/77 or YF-17DD yellow fever (YF) substrains.

Methods: A non-probabilistic sample of eighty healthy primary vaccinated (PV) children was selected on the basis of their previously known humoral immune response to the YF vaccines. The selected children were categorized according to their YF-neutralizing antibody titers (PRNT) and referred to as seroconverters (PV-PRNT(+)) or nonseroconverters (PV-PRNT(-)).

Evaluation of accuracy and reliability of the plaque reduction neutralization test (micro-PRNT) in detection of yellow fever virus antibodies.

Yellow fever is a disease caused by the prototype virus of the genus Flavivirus and remains endemic in tropical forest regions from Africa and South America, despite the availability of effective vaccines. These are capable of inducing a rapid specific immune response, with the formation of neutralizing antibodies that appear early, are protective and long lasting. The Plaque Reduction Neutralization Test is considered the most sensitive and specific test for quantification of neutralizing antibodies, and the reference method for assessing the protective immune response after vaccination.

Cytokine signatures of innate and adaptive immunity in 17DD yellow fever vaccinated children and its association with the level of neutralizing antibody.

Background: The live attenuated yellow fever (YF) vaccines have been available for decades and are considered highly effective and one of the safest vaccines worldwide.

Methods: The impact of YF-17DD-antigens recall on cytokine profiles of YF-17DD-vaccinated children were characterized using short-term cultures of whole blood samples and single-cell flow cytometry. This study enrolled seroconverters and nonseroconverters after primovaccination (PV-PRNT⁺ and PV-PRNT⁻), seroconverters after revaccination (RV-PRNT⁺), and unvaccinated volunteers (UV-PRNT⁻).

Clinical and immunological insights on severe, adverse neurotropic and viscerotropic disease following 17D yellow fever vaccination.

Yellow fever (YF) vaccines (17D-204 and 17DD) are well tolerated and cause very low rates of severe adverse events (YEL-SAE), such as serious allergic reactions, neurotropic adverse diseases (YEL-AND), and viscerotropic diseases (YEL-AVD). Viral and host factors have been postulated to explain the basis of YEL-SAE. However, the mechanisms underlying the occurrence of YEL-SAE remain unknown.

Accuracy and repeatability of a micro plaque reduction neutralization test for vaccinia antibodies.

The detection of neutralizing antibodies against vaccinia virus is a valuable tool for the investigation of previous smallpox vaccination. Compulsory smallpox vaccination ended in Brazil during the early 1970s, although the vaccine was available until the late 1970s. The threat of smallpox as a biological weapon has called the attention of public health authorities to the need for an evaluation of the immune status of the population.

Yellow fever vaccination: some thoughts on how much is enough [Vaccine 23 (2005) 3908-3914].

In a recently published article in this journal, Massad et al. contraindicates yellow fever vaccination to persons 60 years or older, considering that the risk of serious adverse events is higher for this age class. The conclusion was based on the input of available data on age-related probabilities of developing serious adverse events in the United States, as well on other data not firmly established.

Screening of CHO cell clones expressing histidine-tagged major S hepatitis B surface protein using a semi-quantitative PCR protocol.

Different mammalian cells have been used successfully for the expression of the hepatitis B surface antigen (HBsAg). The patterns of expression of the HBsAg seem to depend on the cell type and the number of gene copies integrated into cellular genome. The expression of an HBsAg fused to histidine tag (His-HBsAg), had not been reported in mammalian cells.

Simple immunoaffinity method to purify recombinant hepatitis B surface antigen secreted by transfected mammalian cells.

Purification of recombinant hepatitis B surface antigen (recHBsAg) produced in a stable Chinese hamster ovary (CHO) cell line was evaluated using Linx Affinity Purification System (Invitrogen, USA). To purify HBsAg secreted by this cell line, a murine monoclonal antibody (MAbAH1) raised against native HBsAg was used. The purified AH1MAb was conjugated with phenyldiboronic acid (PDBA) and immobilized on the immunoaffinity chromatographic support.

Identification and characterization of avian retroviruses in chicken embryo-derived yellow fever vaccines: investigation of transmission to vaccine recipients.

All currently licensed yellow fever (YF) vaccines are propagated in chicken embryos. Recent studies of chick cell-derived measles and mumps vaccines show evidence of two types of retrovirus particles, the endogenous avian retrovirus (EAV) and the endogenous avian leukosis virus (ALV-E), which originate from the chicken embryonic fibroblast substrates. In this study, we investigated substrate-derived avian retrovirus contamination in YF vaccines currently produced by three manufacturers (YF-vax [Connaught Laboratories], Stamaril [Aventis], and YF-FIOCRUZ [FIOCRUZ-Bio-Manguinhos]).