UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG

Knowledge creation, neglected infection

15 February 2012

Witnessing Prof. Anna Kramvis, Leader of the Hepatitis B Virus Diversity Research Programme (HVDRP), working with and developing her team of postgraduates is testimony to the importance of Wits’ strategic plan to develop its reputation as a research-driven institution.

The team comprises two postdoctoral fellows, six doctoral and two masters degree students, participating in cutting edge research in the field of molecular biology, which has been identified as a scarce skill by the National Research Foundation of South Africa (SA).

Kramvis has worked in the field of viral hepatitis for the past 15 years and has gone more than the extra mile to secure funding for her programme. While chronic Hepatitis B (HBV) is listed in the top ten diseases in the world, funding is often limited because AIDS, malaria and Tuberculosis (TB) overshadow it in Africa.

Sequence variation of hepatitis viruses

Her team’s focus is the study of sequence variation of hepatitis viruses, their functional characterisation and their role in the clinical manifestation of liverProf. Anna Kramvis and her team disease.

“The hepatitis B virus is incredibly sophisticated and classified into nine genotypes and at least 32 subgenotypes,” Kramvis explains.

“In Africa we get genotypes A, D and E, with subgenotype A1 predominating in SA, while A2 is found outside Africa. Subgenotype A1 develops certain mutations that A2 does not and A1 has been shown to be more prone to causing liver cancer.”

“Therefore results generated from other regions of the world cannot be extrapolated to Africa,” Kramvis continues.

One percent of the world’s chronic carriers of HBV resides in southern Africa and while there is a successful vaccine against HBV, which was introduced in SA in 1995, those already infected, can go on to develop liver cancer.  

“In order to combat HBV infection and the end result of this infection, that is, liver cancer, using antiviral and anti-tumour treatment modalities, respectively, one has to study the virus and the mechanisms of tumourigenesis in depth,” Kramvis explains.

Subgenotype A1 clones

To this end, doctoral student Nimisha Bhoola has constructed subgenotype A1 clones in order to follow viral replication in tissue culture, as well as in the transgenic mouse model.  This, after work carried out by doctoral students Chien-Yu Chen and Raquel Viana, showed that the mutant virus can produce a protein that accumulates in liver cells and leads to programmed cell death, which may contribute to the development of liver cancer. 

As part of an 18-month study funded by the Medical Research Council of SA and the Cancer Association, doctoral student Trevor Bell established a cohort in Shongwe, Mpumalanga in order to study HBV-HIV co-infection. 

Together with masters student Euphodia Makondo, they identified 72 individuals out of 300, who had markers for HBV before the start of antiretroviral treatment (ART) and sequenced the HBV strains. 

“As far as we know, in Africa the HBV precedes HIV. HBV appears to be transmitted horisontally, usually between siblings and playmates, as opposed to the mother-to-child and sexually related transmission of HIV,” Kramvis explains.

The programme’s two postdoctoral fellows, Drs Shobna Chauhan and Deepak Gopalakrishnan, both from India, are continuing the study by following the evolution of the virus in the co-infected patients after the initiation of treatment. 

“Of the 72 participants who had HBV markers only 26, or 9% had HBs antigen (a viral protein), indicating overt infection. This is an average statistic for SA where HBV is hyperendemic (more than 8% infection),” says Kramvis.

Silent infection

“What was revealing is that 15% tested negative for HBsAg but positive for HBV DNA (nucleic acid testing, which is the best and most sensitive form of testing). This is what we call an occult or silent infection.” 

Doctoral student Caroline Dickens characterised such an infection in baboons.  What this means is that none of these infections would have been conventionally detected. HBV DNA testing is too expensive to be universally used in SA.

“This information is critical in the treatment of HBV-HIV co-infected patients because the introduction of ART can lead to the promotion of resistant viral strains, to reactivation of disease and hepatoxicity. Therefore, it is important that the HBV strains in HIV-infected individuals are closely studied,” adds Kramvis.

The fact that these patients were about to start ART is significant in other ways. Kramvis explains:

“Approximately 20% of HBV infected patients develop drug-resistance mutations every year they are on Lamivudine, which is used for HIV treatment. Hence the call by clinicians to change to other treatment drugs, such as the newer Tenofovir when this occurs.”

Bioinformatic tools

In 2010, Bell started developing in-house bioinformatic tools – programmes geared to analyse the sequences the team is working on – in order to automate the processing of sequences instead of doing it manually, which will considerably speed up the process. This project is scheduled for completion in 2012 and has assisted in characterising HBV strains from cancer patients sequenced by masters student Mark Keyter. 

Grant from the DFG

In May 2010 the HVDRP received a large grant, including bursaries, equipment and running expenses from the German Research Foundation (DFG) to look at HBV strains in Sudan and the rest of Africa.

It is a tripartite partnership between Wits, the University of Khartoum in Sudan and the Justus Liebig University Giessen in Germany.

Work started in July 2010. Called the Africa Initiative, it is aimed at capacity development in the study of neglected diseases in Africa.

“We chose Sudan because nothing is known about the genotypes in that region,” Kramvis explains.

“Sudan provides an interesting crossroad in Africa. The genotypes prevailing there could be related to the spread of the Islamic Empires and/or the slave trade. In fact, we have recently identified differences between subgenotype A1 strains that may be used to trace human migrations,” she says.

“We have a doctoral student from the Sudan, Mukhlid Yousif, working on the project and we are looking at overt and occult HBV infections in relation to liver disease. Apart from finding genotypes D and E, we have found our first subgenotype A1 strain in Sudan.”

The programme’s output is extensive and includes collaborations between SA and Australia, Belgium, Germany, Greece, Kenya, Japan and Sudan.

Kramvis thoroughly enjoys working with students and partners from all over the world.

“The teamwork and the capacity to develop students is incredibly rewarding,” she concludes.  

This article first appeared in the Wits 2010 Research Report. Read it here