A Genome Wide Association study (GWAS) on susceptibility to sexual transmission of HCV among HIV-1+ MSM

With an estimated 180 million people infected, hepatitis C virus (HCV) presents
a major health problem globally. Ongoing inflammation of the liver during
chronic HCV infection may ultimately progress to liver cirrhosis and
hepatocellular carcinoma, resulting in 700,000 HCV-associated deaths each year
(1, 2). The recent availability of *direct acting antivirals* heralded a
remarkable improvement in treatment outcome, with >95% of patients achieving
viral clearance and reduction of side effects. However, despite this tremendous
improvement, the burden of disease will remain substantial for a variety of
reasons. Firstly, cirrhotic patients remain at risk for hepatocellular
carcinoma, also after successful antiviral treatment. Secondly, chronically
infected patients are usually unaware of their HCV-positive status during the
long asymptomatic phase of the infection. Last but not least, diagnostics are
unavailable and treatment is unaffordable in many parts of the world, creating
huge challenges to eliminate HCV globally.

Since blood products in general have become safe, people who inject drugs
(PWID) remain the predominant risk-group for incident HCV infection. However,
since the beginning of this millennium, HCV is also spreading by sexual
transmission among HIV infected *men who have sex with men* (MSM), which is
remarkable as sexual transmission of HCV was considered very rare for a long
time. In the Netherlands, where the epidemic among PWID has declined due to
needle-exchange programs and changes in injecting drugs behaviour, HIV infected
MSM are currently the main risk-group for incident infection, with high rates
of reinfection following successful treatment of primary infection (3*5) . With
the arrival of pre-exposure prophylaxis (PreP) for HIV, there is concern that
Hepatitis C will spread to HIV negative MSM as well. Indeed, an HCV prevalence
of 4% among HIV negative MSM was observed during a HIV PreP pilot project in
Amsterdam, which is substantially higher than the prevalence of 0.2% in the
general population (6).

Nevertheless, despite high-risk behavior facilitating HCV transmission and
substantial prevalence in the population, some individuals remain uninfected
(multiple exposed uninfected, MEU), suggesting that host factors play a role
in HCV susceptibility . In a small pilot study among participants of the
Amsterdam Cohort Studies and the MOSAIC cohort, specifically studying HCV entry
factors, we indeed found a few genetic polymorphisms that appeared to be
associated with HCV acquisition. Linking specific host genotypes with risk of
HCV acquisition and identifying the inhibitory mechanism will undoubtedly lead
to new host molecules that antivirals can target. The best example of such an
approach is the development of Maraviroc, a drug blocking the HIV-1 CCR5
co-receptor which was found to be dysfunctional in high-risk uninfected
individuals.

Aim of the study proposed here is to perform a genome wide association study
(GWAS) on individuals at high risk for acquiring HCV, to identify
polymorphisms in host genes which influence HCV susceptibility.

To identify genetic host factors associated with HCV susceptibility among
HIV-infected MSM.

The study is a case-control study. Cases are HIV-infected MSM with current or
past HCV infection. Controls are HIV-infected MSM without HCV infection.
Controls will be asked to fill out a questionnaire which enables assessment of
risk behavior. In the final GWA study, only controls with high risk behavior
(as evidenced by a risk score >= 2, see below) will be included for genetic
testing.

This study will be done in collaboration with several locations in Amsterdam,
New York and Berlin. DNA will be collected prospectively by buccal dry cotton
swabs. The HCV status will be determined by HCV antibody testing, ALT levels
and/or HCV RNA detection. Also will the participants be asked to fill in a
questionnaire on risk behavior for acquiring HCV. The swabs collected outside
the Netherlands will be stored in transport medium at room temperature and
shipped to the Netherlands for DNA isolation. We aim to analyze a minimum of
500 cases and 500 controls, which is sufficiently powered to identify SNPS with
ORs between 1.5 and 2, depending on the gene frequency. The GWAS will be
performed at a GWAS facility at the EMC in Rotterdam. On the array 700.000 SNPs
will be analyzed and up to 4 million can be computed from that data. These SNPs
will have a minor allele frequency (MAF) score ranging between 0.05-0.5. Data
analysis and statistics will be performed in collaboration with Michael Tanck
from the data analysis department at the AMC. A logistic regression (additive,
dominant and no genetic model) will be performed on the data to estimate the
Odds Ratio for specific SNPs and HCV. Controlling for multiple testing to
accurately estimate significance the generally accepted 5 x 10^-8 threshold
will be used. For the analysis we will be supported by the biostatistics
department of the AMC (Michael Tanck)

Recruitment will take place between January 1st 2017 and August 1st 2017.
Data-analysis and writing of manuscript deadline is 31st December 2017.

The inclusion can happen after regular poli visit so no extra visit to the
hospital has to be made.
Inclusion will take about 15 minutes of a participants time.
The questionnaire consists of very personal questions wich can be experienced
as unpleasant. However, there is always the option to skip a particular
question.
Buccal swabs will be taken from the patient. This is a minimally invasive
method.