Development of reverse transcription loop-mediated isothermal amplification for detection of Rhinovirus C
During worldwide surveillance for emerging respiratory viruses in the late 2000s, Rhinovirus C (RV-C) was identified from previously unseen to clinical detection using molecular detection. RV-C is closely associated with severe hospitalized infections and exacerbation of chronic pulmonary disease...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/90052/1/FPSK%20%28m%29%202019%2041%20UPM%20ir.pdf http://psasir.upm.edu.my/id/eprint/90052/ |
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| Institution: | Universiti Putra Malaysia |
| Language: | English |
| Summary: | During worldwide surveillance for emerging respiratory viruses in the late
2000s, Rhinovirus C (RV-C) was identified from previously unseen to clinical
detection using molecular detection. RV-C is closely associated with severe
hospitalized infections and exacerbation of chronic pulmonary diseases
(COPDs). However, unlike RV-A and –B, RV-C is unculturable in standard
tissue culture. Therefore, molecular detection became important for the
diagnosis of RV-C. Several molecular diagnostics assays such as reverse
transcription polymerase chain reaction (RT-PCR) either single or multiplex
and probe-based real-time PCRs are made available. However, only several
laboratories have access to these diagnostic assays due to their costs and
time-consuming process, therefore unavailable and unaffordable, for
accurate and rapid virological confirmation.
This study used a new molecular approach, known as loop-mediated
isothermal amplification (LAMP) for rapid detection and differentiation of RVC
from -A and -B. LAMP is known for its rapid amplification of target template
under isothermal conditions, visible naked eyes observation for positive
results, much simpler, low cost, and rapid in the disease diagnosis. In this
study, new oligonucleotides targeting 5’UTR were designed based on 20 RVC
sequences, comprising available Malaysia sequences and neighboring
countries such as Hong Kong, China and Thailand. Four sets of primers (Set
1-4) were specially designed for amplification using free online software and
all sets of primer were tested. Selected primers were tested with
temperatures ranging from 60-65˚C, varying concentrations of MgSO4 (2-12
mM) and betaine (0-1.2 M), primer concentration ratios between outer primer
to inner (1:1-1:12) and reaction time for optimal LAMP reaction. Of four set
of primers tested, only Set 1 primer showed positive amplification whereas
Set 2-4 showed negative amplification. Hence, Set 1 primer was used for
further optimization. LAMP with Set 1 primer detected RV-C at 61˚C for 40 minutes of incubation, of approximately three times faster than PCR. The
final LAMP assay comprised 5 pmol each of outer primer F3 and B3, 40 pmol
each of inner primer FIP and BIP (primer ratio of 1:8), 8 mM of magnesium
ion (Mg2+) and 0.8 M betaine. Set 1 primer showed high LAMP efficiency and
sensitivity, with a quantifiable viral load as low as 104 copies of RNA within
40 minutes.
This RT-LAMP assay was evaluated with known RV-As, -Bs, -Cs and other
respiratory virus infected clinical samples. The RT-LAMP was able to detect
all RV-C isolates. RT-PCR was carried out in parallel with LAMP outer
primers (F3 and B3) and amplicons were purified and sequenced.
Sequences analysis indicated RV-Cs, thus further verifying the specificity of
the developed RT-LAMP. The present study offered better detection of RVCs
as compared to existing methods. However, improvements such as
primer design and inclusion of more samples are required for differentiation
of RV-C from RV-A and RV-B. |
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