Yellow Fever Virus Genotyping Tool and Investigation of Suspected Adverse Events Following Yellow Fever Vaccination

Abstract

The yellow fever (YF) vaccine consists of an attenuated virus, and despite its relative safety, some adverse events following YF vaccination have been described. At the end of 2016, Brazil experienced the most massive sylvatic yellow fever outbreak over the last 70 years and an intense campaign of YF vaccination occurred in Minas Gerais state in Southeast Brazil from 2016 to 2018. The present study aimed to develop a genotyping tool and investigate 21 cases of suspected adverse events following YF vaccination. Initial in silico analyses were performed using partial NS5 nucleotide sequences to verify the discriminatory potential between wild-type and vaccine viruses. Samples from patients were screened for the presence of the YFV RNA, using 5′UTR as the target, and then used for amplification of partial NS5 gene amplification, sequencing, and phylogenetic analysis. Genotyping indicated that 17 suspected cases were infected by the wild-type yellow fever virus, but four cases remained inconclusive. The genotyping tool was efficient in distinguishing the vaccine from wild-type virus, and it has the potential to be used for the differentiation of all yellow fever virus genotypes.

Neighbor danger: Yellow fever virus epizootics in urban and urban-rural transition areas of Minas Gerais state, during 2017-2018 yellow fever outbreaks in Brazil

“…We observed the widespread circulation of YFV in Minas Gerais, detecting the virus in 49 municipalities where YF was not previously reported during the recent YF outbreaks [14,25,26]. In Minas Gerais state, the mesoregions with the highest numbers of YFV-positive carcasses were the same ones with the highest records of human YF cases from 2016 to 2018 [4,14,23,24]. Our phylogenetic analyses confirmed the YFV in different urban areas of Minas Gerais, close to human populations.…”

“…RNA extraction was performed in batches of 11 samples plus one negative control (nuclease-free water). RNA samples were submitted to a one-step real-time polymerase chain reaction (RT-qPCR), with primers targeting the gene coding for β-actin [23], using GoTaq 1-Step RT-qPCR System (Promega, USA). All samples were positive, showing the suitability of samples for RT-qPCR.…”

Yellow Fever Molecular Diagnosis Using Urine Specimens during Acute and Convalescent Phases of the Disease

“…Two urine samples, from the convalescent phase of YF infection (67 and 69 DPS), were collected from patients who received YF vaccine 10 days before symptom onset (ID 14 and ID 15; Table 1 ) and were genotyped as previously described ( 20 ), to investigate possible persistence of the YFV vaccine strain. We were also able to genotype YFV from other three urine samples collected during acute YF infection (GenBank accession number: OM692343 to OM692349 ) ( Table 1 and Fig.…”

“…Urine samples presenting YFV RNA were genotyped ( 20 ). For this, 5 μL of total RNA obtained from a positive urine sample was submitted to a different RT-qPCR, using primers targeting the NS5 region ( 21 ), and amplicons were used for nucleotide sequencing ( 22 ).…”

“…For this, 5 μL of total RNA obtained from a positive urine sample was submitted to a different RT-qPCR, using primers targeting the NS5 region ( 21 ), and amplicons were used for nucleotide sequencing ( 22 ). The sequences generated were then aligned with a sequence panel previously used ( 20 ), using Clustal W, implemented on Mega7 ( 22 ). The Maximum-likelihood tree was generated using Kimura-2-parameters nucleotide substitution model with gamma distribution and 1,000 bootstraps replicates, using MEGA7 ( 23 ).…”