Chit Laa Poh, PhD
Distinguished Professor of Biological Sciences
- : +60-162363293
Current Research Conducting research activities in Virology and Co-supervision of MSc and PhD student at Sunway University and the University of Malaya
Medical Virology in Sunway University & University of Malaya
Enterovirus 71 is a viral agent capable of causing serious infections in young children (<6 years old) and the disease elicited is known as hand, foot and mouth disease (HFMD). It has been associated with neurological complications with high fatalities in several major outbreaks in the Asia-Pacific. In 2000, there were 6000 cases of HFMD being reported in children in Perth and some 2000 cases in Sydney, Australia, after an earlier outbreak in Malaysia in 1999 with 57 deaths. Singapore experienced a major HFMD outbreak in 2000, resulting in 5 deaths and lately in China there were more than 1.5 million cases with 257 deaths in 2013. Children have been known to develop acute flaccid paralysis and some have died from pulmonary edema. Children who had suffered serious HFMD infections and recovered were reported to manifest long term neurological complications. EV71 virus is endemic in China, Malaysia and Singapore and serious outbreaks with high fatalities can occur again in all three countries if there is a highly virulent strain involved. Currently, there is no FDA approved vaccine or anti-virals that are known to prevent or treat this viral infection.
I have been engaged in research activities to develop rapid diagnostics for detection of EV71 from clinical materials, active and passive immunization, exploring RNA interference as a potential antiviral therapy and development of antiviral peptides against EV71.
Development of an attenuated EV71 vaccine
In order to develop an effective vaccine against EV71, an in-depth understanding of the biological characteristics of the EV71 genome and the immune correlates of protection against the virus is needed. About 123 EV71 strains have been fully sequenced and so far there is no known correlation of any amino acid change with pathogenecity. My current research is focused on gaining an understanding of the molecular basis of Enterovirus 71 neurovirulence.
Research activities will be concentrated on the construction of attenuated strains by isolating a strain carrying a high fidelity variant RNA polymerase and introducing miRNA targets into the viral genome to reduce pathogenicity of the virus in neuronal cells. These research efforts will generate journal papers suitable for publication in high impact factor journals and there is great potential for commercial exploitation of the novel viral strains constructed. There is a high chance for patenting the strains constructed and developing the vaccines for immunization.
I was invited by Humana Press to contribute a chapter on “Detection of Enteroviruses from clinical materials” following publishing several papers on “Rapid detection of Enterovirus 71 by real-time RT-PCR from clinical specimens.” The book entitled “Diagnostic Virology Protocols” has now been published and there is an expectation of high demand by the international community.
Development of antiviral peptides against EV71
Enterovirus 71 (EV-71) is the main causative agent of hand, foot and mouth disease (HFMD). In recent years, EV-71 infections were reported to cause high fatalities and severe neurological complications in Asia. Currently, no effective antiviral or vaccine is available to treat or prevent EV-71 infection. We have discovered a synthetic peptide which could be developed as a potential antiviral for inhibition of EV-71. Ninety five synthetic peptides (15-mers) overlapping the entire EV-71 capsid protein, VP1, were chemically synthesized and tested for antiviral properties against EV-71 in human Rhabdomyosarcoma (RD) cells. One peptide, SP40, was found to significantly reduce cytopathic effects of all representative EV-71 strains from genotypes A, B and C tested, with IC50 values ranging from 6 - 9.3 µM in RD cells. The in vitro inhibitory effect of SP40 exhibited a dose dependent concentration corresponding to a decrease in infectious viral particles, total viral RNA and the levels of VP1 protein. The antiviral activity of SP40 peptide was not restricted to a specific cell line as inhibition of EV-71 was observed in RD, HeLa, HT-29 and Vero cells. Besides inhibition of EV-71, it also had antiviral activities against CV-A16 and poliovirus type 1 in cell culture. Mechanism of action studies suggested that the SP40 peptide was not virucidal but was able to block viral attachment to the RD cells. Substitutions of arginine and lysine residues with alanine in the SP40 peptide at positions R3A, R4A, K5A and R13A were found to significantly decrease antiviral activities, implying the importance of positively charged amino acids for the antiviral activities. The data demonstrated the potential and feasibility of SP40 as a broad spectrum antiviral agent against EV-71. The discovery has been filed for a patent in Malaysia. I am currently working with the full D-amino acid substituted peptide, partial D-amino acid substituted and truncated peptides to evaluate their serum stability and antiviral activities.
Inhibition of EV71 by anti-sense antiviral agent
HFMD is endemic in Singapore and the Asia Pacific and the number of cases can escalate to thousands of cases in outbreak situations. It is unknown if the strain involved in an outbreak will be virulent and the association with fatalities is also unknown. An outbreak caused by a virulent strain of EV71 will significantly affect a country’s economy as most of the childcare and pre-school centres will be closed for up to 10 days. This was the situation in Singapore in 2000 when there was an outbreak caused by a virulent EV71 strain. Therefore, it is important to work on the development of an antiviral in an outbreak situation before an effective EV71 vaccine becomes available. My laboratory has developed an antisense octaguanidinium dendrimer-conjugated morpholino oligomers. Inhibitory effects of vivo-morpholinos targeting the IRES and 3D polymerase were compared. Two vivo-morpholinos targeting the IRES showed significant plaque reductions. Both vivo-MO-1 and vivo-MO-2 reduced viral RNA copies and capsid protein expression in RD cells in a dose-dependent manner. Both vivo-MOs were inhibitory when administered either 4 h before or withn 6 h after EV71 infection. However, resistant mutants arose against vivo-MO-1 after serial passages in the presence of vivo-MO-1 , but none were isolated against vivo-MO-2.Our findings suggest that IRES-targeting vivo-MOs are good antiviral candidates for treating early EV-71 infection and vivo-MO-2 is a more favorable candidate with broader antiviral spectrum against enteroviruses and are refractory to antiviral resistance. The data were submitted to Malaysian agency for filing as a provisional patent in January, 2014.
As Asia is constantly subjected to outbreaks of diseases such as HFMD caused by Enterovirus 71, there is a great potential to undertake a research theme on the Development of vaccines and antivirals against EV71 and other Picornaviruses. This will enable a buildup of research personnels who can work in teams and build up the research capability of an institution. Such research activities will lead to commercially valuable IP and products, publications in prestigious journals and training of valuable scientific research manpower for the country.
Molecular Environmental Microbiology
Distinguished Professor of Biological Sciences