Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

published_or_final_version / Public Health / Master / Master of Public Health

Background: Isolation of respiratory viruses routinely requires a panel of cell lines. Management of these cell lines is usually considered complex, cumbersome, long turnaround time and high cost. In order to improve the detection rate and cost, there is a need to evaluate any other cell line that could be as sensitive as the routine cell line for the detection of respiratory viruses. The human colon adeno-carcinoma (Caco-2) cell line has been shown to support the growth of enteroviruses, enteric viruses, and influenza A virus, and ability to grow coronavirus NL63 and SARS from culture isolates. In the present study, the isolation rate of respiratory viruses in Caco-2 from clinical specimens was studied and compared with the conventional panel of cell lines for the diagnosis of respiratory virus disease. Material and methods: The study was performed in two stages. In the first stage, one hundred and eighty-nine nasopharyngeal aspirates confirmed positive by direct immunofluorescence were used to inoculate onto Caco-2, and HEp-2, A549, MDCK, LLC-MK2 cell lines at the same time. In the second stage, fifty-six nasopharyngeal aspirates were randomly selected and cultured on Caco-2, HEp-2, A549, MDCK and LLC-MK2. Infected cells were examined daily for cytopathic effect for up to 10 days. Virus was further identified by performing direct immunofluorescence test for detection of eight common respiratory viruses (respiratory syncytial virus, influenza A and B viruses, parainfluenza type 1, 2, 3, 4 viruses and adenovirus). Results: Caco-2 (84%) was found to be the most efficient cell line to propagate the respiratory viruses from nasopharyngeal aspirate when compared with any positive by these conventional panel cells (78%) or individual cell line MDCK (38%), HEp-2 (21%), LLC-MK2 (27%) and A549 (37%). The latter differences were statistically significant (p = <0.000001). Furthermore, Caco-2 recovered 86% (36/42) viruses of conventional panel cells negative samples, while conventional panel cells recovered 80% (24/30) viruses of Caco-2 cells negative samples. Conclusion: Caco-2 is sensitive to a wide range of virus and can greatly simplify routine cell culture service for isolation of respiratory viruses. / published_or_final_version / Microbiology / Master / Master of Medical Sciences

Asia has populated with the second largest number of people living with HIV/AIDS. Under the advancement of transportation, the open up of borders between cities and countries, and the process of globalisation, people move from their place of origin to other places for better living conditions and employment opportunities. Mobile people and migrants are identified as the high risk population of HIV infection. Poverty, discrimination, limited access to healthcare and social services, separation with supports and families, being alienated in resident communities, and gender inequalities are the unfavourable conditions which make the migrant population vulnerable to HIV infection. Existing literatures have investigated and examined the potential risk factors among the mobile population. Inconsistencies were found among research but high risk sexual behaviours and poor knowledge and attitude were observed and reviewed within the migrants. However, literatures which compared the people who migrated with other local people in the same population were not yet reviewed systemically. Therefore, this paper aimed to review the articles which compare the migrant group and the non-migrant group in Asian population to identify the association between migration and the risks of HIV infection. A literature search of five databases (PubMed, Medline, Cochrane, CNKI, Wanfang Med Online) was performed and nine articles were eventually selected for review. The migration status of literature was studied as explanatory variable and compared across studies. Outcome variables of interest were grouped into four categories as: demographic characteristics, sexual practices, awareness towards HIV/AIDS, and disease prevalence. To conclude, compared to people who did not migrate, migrants in Asia were more tend to be less educated, have multiple sex partners, engage in high risk sexual intercourse and commercial sex, but their overall condom usage were lower. Also, they had higher risk of sexually transmitted infections and poorer knowledge in HIV/AIDS. / published_or_final_version / Public Health / Master / Master of Public Health

Infection control is an often neglected clinical subject in Hong Kong until the outbreak of severe acute respiratory syndrome (SARS) in 2003. A total of eight healthcare workers, including four medical doctors, succumbed as a result of nosocomial acquisition of SARS-coronavirus (SARS-CoV) at the time. Since then, the importance of infection control practice was much better appreciated by the frontline healthcare workers, as it can be a matter of life-or-death. My thesis summarized our research on the proactive infection control measures to prevent nosocomial transmission of respiratory and gastrointestinal viruses, to control emerging and endemic antibiotic-resistant bacteria, and on the management of unprecedented infection outbreaks in the hospital. Promotion of hand hygiene is the cornerstone of proactive infection control measures. By adopting the concept and practice of directly-observed hand hygiene, we demonstrated successful control of outbreaks and prevention for both respiratory and gastroenteritis viruses. Introduction of electronic devices for continuous monitoring of hand hygiene compliance in high risk clinical areas provides an opportunity for immediate feedback and timely education to frontline staffs. The global dissemination of multiple drug resistant organisms (MDROs) such as methicillin-resistant Staphylococcus aureus (MRSA), community-associated MRSA (CA-MRSA), vancomycin-resistant enterococcus (VRE), hypervirulent clone of Clostridium difficile, extended-spectrum beta-lactamase (ESBL) producing organisms, and the recently described carbapenem-resistant enterobacteriaceae (CRE), pose a great challenge to the infection control professionals. In Hong Kong, MRSA has been endemic for more than two decades. Although we proved that the appropriate use of single room isolation and hand hygiene can significantly reduce the incidence of nosocomial MRSA in the adult intensive care unit, the isolation facilities remain limited in the general medical and surgical units. Innovations are much in need to manage this old and persistent problem. Therefore, we demonstrated that use of antibiotics, in particular beta-lactams and fluoroquinolones, could increase the risk of environmental contamination by increasing microbial density of MRSA in the anterior nares by 2-3 log10 in as little as 1 week. We also found that some MRSA strains such as spa types t1081 and t037 were more transmissible. Based on these findings, we prioritized our isolation facilities for those patients who are heavily colonized or infected with highly transmissible spa-type t1081, especially when they are receiving antibiotic therapy. Along with our enhancement of hand hygiene practices and antibiotic stewardship program, the incidence of MRSA bacteremia per 1000-patient-days was the lowest among the seven hospital clusters in Hong Kong. We believe that our experience in the control of the MRSA can be extended to contain the spread of CA-MRSA and other MDROs. Besides the prevailing infectious diseases with high endemicity, we have to be vigilant against other potential outbreaks due to uncommon micro-organisms such as the polymicrobial outbreak in patients undergoing intermittent peritoneal dialysis caused by hospital renovation, the unprecedented outbreak of intestinal mucormycosis caused by Rhizopus microsporous among the patients with hematological malignancy, and the nosocomial outbreak of legionellosis in our locality. Extensive outbreak investigations were performed, which demonstrated that environmental factors were also important in causing nosocomial outbreaks. / published_or_final_version / Microbiology / Master / Doctor of Medicine

Our research laboratory has recently reported that mucosal priming with a replicating modified vaccinia Tiantan virus (MVTTgpe)-based vaccine elicits durable protection against pathogenic SIVmac239 infection in rhesus monkeys. However, the protective role of vaccine-elicited antibody responses remains poorly understood. Here, a novel yeast surface displayed (YSD) antigen library was established to quantitatively map the antigenic determinants presented by MVTTgpe-based and control vaccines as well as by SIVmac239 infection. The YSD-library allows the mapping of linear and some conformational epitopes as a major technical innovation, as validated by testing SIV-specific mAbs KK65, KK8 and VM-18S. While eight antigenic domains are characterized covering the entire SIVmac239 gp160, the MVTTgpe/Ad5gpe regimen uniquely induces antibody responses against a distinct major antigenic determinant (MAD) in V2 region as compared with the Ad5gpe/Ad5gpe vaccination and SIV infection. This MAD is associated with a higher titer of anti-V2 antibody responses, which inversely correlates with peak viral load. Unexpectedly, the MVTTgpe/Ad5gpe vaccine- challenge. The results showed that instead of recalling B cell memory response to V2, viral infection presents a distinct set of antigenic determinants with anti-V1V2 antibodies primarily directed to V1 region. Moreover, the anti-V1V2 antibody responses disappear in two infected macaques after they enter the stage of simian AIDS. SIVmac239 infection, therefore, can modulate vaccine-elicited B cell immunity by diminishing anti-V2 antibody memory responses in rhesus monkeys. These findings implicated that vaccine efforts with focus on V2 region would require periodic vaccinations to maintain a long-lasting high level of antibody responses for protection. In the absence of an effective vaccine for eliciting HIV-1-specific broadly neutralizing antibodies (bNAbs), passive immunization with bNAbs or Ab-like agents (e.g. immunoadhesin) becomes an attractive alternative for HIV-1 prevention. In this study, we aimed to design, optimize and produce secretory immunoadhesins (IAs) based on gene engineering of existing HIV-1 specific bNAbs for potency and production improvements. IAs are chimeric, antibody-like molecules that combine the functional domain of bNAb with immunoglobulin constant domains, including the hinge and Fc regions. We found that the modified secretory IAs not only preserved the neutralization activity of the parental bNAbs, but also had enhanced expression and smaller molecular size that is suitable for antibody gene-based in vivo delivery. Furthermore, we defined the synergistic effects of five IAs against HIV-1 infection and subsequently engineered two types of bi-specific IAs by combining the functional domains of Hu5A8, a humanized anti-CD4 antibody, and the bNAb PGT128. Significantly, one of the bi-specific IA, namely Bi-IA-Mono, neutralized 100% of the 33 viruses tested, including the transmitted/founder viruses and viruses resistant to both parental IAs. The remarkably enhanced neutralization activity of Bi-IA-Mono, either in potency and breadth, indicated the great potential of modified bi-specific IA to provide complete or nearly complete protection against major HIV-1 subtypes. Overall, our results demonstrated that the engineering of IA and bi-specific IA is an attractive way to improve anti-HIV-1 properties of existing bNAbs, which have significant implications for antibody-based prophylactics in blocking diverse HIV-1 transmissions and infections. / published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy

abstract / Biological Sciences / Doctoral / Doctor of Philosophy

Acquired immunodeficiency syndrome (AIDS) is a major problem in our current society. There are over 35 million of the population that are currently living with human immunodeficiency virus (HIV), and the number of HIV-infected patients are still rising every year in spite of our efforts to control it. Furthermore, within the AIDS affected population, opportunistic infection is a major cause of complications and is the number one cause of death. The HIV trans-activator (Tat) protein plays a major role in the AIDS pathogenesis. HIV-1 Tat is known to cause dysregulation of cytokines such as TNF-α, IL-6, and IL-10 in AIDS patients. In this study we recognized a proto-oncogene, c-Myc, could regulate the cytokine dysregulation caused by HIV-1 Tat in primary blood monocyte derived macrophages (PBMac). By knocking down the expression of c-Myc with gene specific small-interfering RNA (siRNA), we demonstrated that c-Myc may be critical for the expression of the pro-inflammatory cytokines TNF-α and IL-6. HIV-1 Tat was subsequently found to regulate the expression of c-Myc via the activation of dsRNA-activated protein kinase (PKR), ERK1/2 and p38 mitogen-activated protein kinase (MAPK). Furthermore, c-Myc regulation of the pro-inflammatory cytokines was demonstrated to have a role in AIDS related opportunistic infections. HIV-1 Tat was shown to increase the intracellular growth of Mycobacteria avium complex (MAC) within PBMac. This increase in MAC growth was in turn found to be regulated by TNF-α expression controlled by c-Myc. HIV-1 Tat was also demonstrated to induce the expression of RIG-I, a common pattern recognition receptor of double stranded RNA viruses, in PBMac. RIG-I is known to activate the viral immune responses such as the type-I interferon (IFN) and pro-inflammatory cytokine pathways. This induction of RIG-I by HIV-1 Tat was found to be regulated by c-Myc, as well as through other signalling kinases such as p38 MAPK and PKR. Tat induction of RIG-I ultimately led to the induction of IFN-α2 and IFN-β through the expression and nuclear translocation of the interferon regulatory factor-7 (IRF-7). This alteration in type-I IFN expression regulated by HIV-1 Tat and RIG-I was also found to play a role against AIDS related opportunistic infections. HIV-1 Tat is known to increase the infectivity of Kaposi’s sarcoma-related herpesvirus (KSHV), a common opportunistic viral infection. We were able to demonstrate that this increase in KSHV infectivity was regulated by RIG-I and type-I IFN induced by HIV-1 Tat. Lastly, this study also demonstrated how HIV-1 Tat was able to manipulate the expression of IL-8 induced by KSHV in PBMac. HIV-1 Tat was able to mediate the production of IL-8 induced by KSHV by altering the phosphorylation of the p38 MAPK and the signal transducer and activator of transcription-1 (STAT-1). Taken together, the results of this study showed how c-Myc and RIG-I may be able to play critical roles in HIV-1 Tat induced cytokine dysregulation. Furthermore, the importance of these pathways is further demonstrated in their roles in regulating the immune responses against opportunistic infections in AIDS patients. / published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

Thesis (DTech. in the Dept. of Drama and Film Studies.)--Tshwane University of Technology, 2012. / When theatre officially was acknowledged as an interventionist tool in the fight against HIV/AIDS in South Africa in 1996, economic and political evils of apartheid of the past. Unfortunately, as statistics have revealed, this has not been the case, as HIV prevalence levels have continued to rise in all sections of society. In trying to understand the reasons for theatre's failed attempts at changing peoples' sexual behaviour, scholars have identified the non-centrality of cultural norms of target audiences as one of the principal causes.it was hoped that it would effectively and efficiently deal with raising the awareness levels of the South African population of the dangers of HIV, and the consequences of risky sexual behaviour given its immense contribution in creating awareness about the social Health communication experts have agreed that health intervention strategies seem to be controlled by people who do not understand the complexity of the behaviour of their target audiences. Health behaviour theorists have also indicated the need to re-examine intervention approaches by paying more attention to the culture of the target population. This study therefore, investigated the inclusion/non-inclusion of cultural norms of target audiences in the design of theatre's dramatic performances which serves as its intervention instrument. This was done through an examination of three theatre groups' HIV/AIDS campaigns in three provinces of South Africa. Using qualitative study methods, the study probed into whether the cultural values of the communities concerned are encapsulated in the plays performed by the groups to spread awareness of HIV/AIDS.