Name: MARCO ANDRÉ LOUREIRO TONINI

Publication date: 10/03/2021
Advisor:

Name	Role
LILIANA CRUZ SPANO	Advisor *

Examining board:

Name	Role
LILIANA CRUZ SPANO	Advisor *
MOISES PALACI	Internal Examiner *
RICARDO PINTO SCHUENCK	Internal Examiner *

Summary: Rotavirus and norovirus are the leading cause of acute diarrhea in children worldwide.
Host susceptibility according to human histo-blood group antigens (HBGAs) is widely
known for norovirus infection, but is less described for rotavirus. Due to the variable
HBGA polymorphism among populations, we aimed to evaluate the association between
HBGA phenotypes (ABH, Lewis and secretor status) and susceptibility to rotavirus and
norovirus symptomatic infection, and the polymorphisms of FUT2 and FUT3, of children
from southeastern Brazil. Moreover, we evaluated the rotavirus P and G genotypes and
norovirus genotypes infecting these children. Fecal samples from 307 children with acute
diarrhea and buccal swabs from 272 of those were used to detect and determine rotavirus
and norovirus genotypes and HBGAs phenotypes and genotypes, respectively.
Altogether, 100 (36.8%) children were infected with rotavirus and norovirus. The
rotavirus G12P[8] (48,6%) genotype was the most frequently among the samples
followed by G3P[8] (11,4%) and G2P[4] (5,7%). The nucleotide sequencing of G3P[8]
samples, the only genotype detected in the 2018 samples, demonstrated that they
belonged to the emergent G3P[8] “equine-like” genotype, the strain that predominates
currently in cases of diarrhea in Brazil and worldwide. Most of the noroviruses (93.8%)
belonged to genogroup II (GII). GII.4 Sydney represented 76% (35/46) amongst five
other genotypes. Rotavirus and noroviruses infected predominantly children with secretor
status (97% and 98.5%, respectively). However, fewer rotavirus-infected children were
Lewis-negative (8.6%) than the norovirus-infected ones (18.5%). FUT3 single nucleotide
polymorphisms (SNP) occurred mostly at the T59G > G508A > T202C > C314T
positions. The predominance of emerging genotypes in the study shows the importance
of continuous surveillance of rotaviruses in order to monitor the emergence of unusual
genotypes and the impact they can bring to the vaccination program. In addition, our
results reinforce the current knowledge that secretors are more susceptible to infection by
both rotavirus and norovirus than non-secretors. The high rate for Lewis negative (17.1%)
and the combination of SNPs, beyond the secretor status, may reflect the highly mixed
population in Brazil.

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