[Blueboard] MS Chemistry Thesis Defense of Mr. Nikita Bacalzo

Gina B. Mamauag gmamauag at ateneo.edu
Thu Jun 11 08:57:43 PHT 2015

The Department of Chemistry

School of Science and Engineering

Invites you to the MS Thesis Defense of

*Mr. Nikita Bacalzo Jr.*

*MS in Chemistry*



1.       Wilberto Ramon Monotilla, PhD

2.       Olivia Erin M. Buenafe, PhD

3.       Lea Cristina Macaraig, PhD


1.       Erwin P. Enriquez, PhD

2.       Nina Rosario L. Rojas, PhD

*Date:* 16 June 2015

*Time:*  10:00 am

*Venue*: C205, Schmitt Hall

*Thesis Abstract:*

                *Shrimp diseases are a major risk in shrimp aquaculture
industry, and for effective farm management, early detection of these
diseases such as using a point-of-care diagnostic can reduce this risk.
Major threats include the recently discovered acute hepatopancreatic
necrosis disease (AHPND) caused by a certain strain of *V. parahemolyticus*,
and the white spot syndrome disease caused by white spot syndrome virus
(WSSV). In this study, different designs of DNA-based lateral flow strip
biosensor (LFSB) were investigated for detection of the WSSV and AHPND
pathogens in shrimp. First, competitive-based LFSB was developed for
detection of WSSV viral genome in infected shrimp tissue samples. DNA probe
sequences based on the WSSV genome was used and conjugated to gold
nanoparticles (AuNP) as the detector-reporter probes. DNA extracts from
WSSV-infected shrimp samples were tested and yielded positive results (i.e.
absence of test line) up to 1:100 dilution, while DNA from WSSV-negative
shrimp samples yielded negative test outcome (i.e. presence of test line).
Images of the strips were analysed digitaly. Mean peak areas of the test
line between the negative and positive samples were established to be
statistically significantly different (*p* < 0.01), although few cases of
false negative outcomes were also observed. Based on the one-step PCR
positive as the cutoff for the peak area, the sensitivity and specificity
of the strips were calculated to be 92.6% and 92.9%, respectively. For the
second design, sandwich-based LFSB was used to detect synthetic DNA targets
as mock for the AHPND bacterial DNA and also WSSV viral genome. Two
sub-designs were developed under this category. First, a single-analyte
detection of AHPND which gave a visual detection limit of 10-7 *M* of DNA
target with sensitivity and specificity of about 71.4% and 92.6%,
respectively. Second, a dual-analyte detection for AHPND and WSSV using
synthetic DNA targets yielding detection limit of 10-7 *M* for each target
DNA. These designs are the first test strip for AHPND detection and also
the first aimed for simultaneous detection of AHPND and WSSV. Overall, this
study demonstrates the superiority of genome-based detection over that of
antibody-based LFSB in terms of fast adaptability for emerging pathogens
and easy design of the detector probes. *

Keywords: lateral flow strip biosensor, WSSV, EMS, AHPND, shrimp pathogens,
gold nanoparticles

*Gina Mamauag-Buan*

*Chemistry Department*
*Ateneo de Manila University*
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