masterThesis
Desenvolvimento de ferramentas moleculares para identificação de variantes genotípicas do vírus causador da Síndrome da Mancha Branca em camarões
Fecha
2018-06-29Registro en:
PEREIRA, Jéssica Marina de Paiva. Desenvolvimento de ferramentas moleculares para identificação de variantes genotípicas do vírus causador da Síndrome da Mancha Branca em camarões. 2018. 56f. Dissertação (Mestrado em Bioquímica) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2018.
Autor
Pereira, Jéssica Marina de Paiva
Resumen
The northeastern region is responsible for more than 90% of shrimp produced in
Brazil, including the two largest producers, the states of Ceará and Rio Grande do
Norte. The virus that causes white spot syndrome (WSSV) has been considered a
major challenge faced by global shrimp farming in recent decades. Despite the fact
that it is the biggest problem facing Brazilian shrimp farming today, the
epidemiological status and the genetic variability of the WSSV have been little
studied in Brazil to date. The genetic variability of WSSV has been investigated in
different regions of the world, especially in studies of viral dispersion and in attempts
to correlate genotype and virulence. This variability is accessed primarily through the
variable regions present at the insertions between ORFs 23/24 and 14/15, and
variable number of tandem repeats (VNTRs) occurring in ORFs 75, 94 and 125. The
primers used to genotype the WSSV based on these regions have been described
for at least 10 years, and some do not work efficiently to genotype new WSSV
variants including those occurring in Brazil. In the present work, a new set of primers
was developed to amplify the variable regions in the WSSV genome by PCR, based
on alignments of all the sequences available so far in the public databases. The new
primers were synthesized, and new PCR reactions were standardized, having their
efficiency compared to previously described protocols and primers. The new primers
were used in a pilot epidemiological study in which shrimp samples were collected on
farms located along the coast of Rio Grande do Norte. The prevalence of WSSV was
58%, 100% and 60% in the farms investigated in the southern, central and northern
regions respectively. The samples with the highest viral load were genotyped. The
new set of primers proved to be more efficient in comparison with the primers already
described, allowing the genotyping of more samples. The results indicate that WSSV
prevalence in the state of Rio Grande do Norte was high at the time the samples
were collected and that the genetic variability of WSSV in the state is low and was
observed mainly in the ORF94 marker. The results allowed to observe some
evidence that events of genetic recombination may have originated the Brazilian
isolates of WSSV.