200 S.I. Wanzala and S. Sreevatsan
by proteomics, transcriptomics, and meta-
bolomics would greatly enhance the efficacy of
biomarkers.
13.8 Biomarker ChallengesMajor challenges in TB diagnostics include the
absence of effective tools for appropriate and
accurate TB diagnosis, as well as well-defined
tools to monitor treatment response to enable
shorter courses of chemotherapy for human
patients and faster turnaround for farmers with
a suspected cattle TB case. Although there is
ongoing research on biomarkers in humans,
new tools for TB diagnosis in animals are not as
abundant (Vordermeier et al., 2016a). There
have been major issues with reproducibility in
biomarker research and this has been put down
to inattentiveness to methodological issues of
study design and performance, which have been
repeatedly claimed as a major reason for false-
positive findings in biomarker research (Pesch
et al., 2014). Another significant challenge with
biomarker research is the lack of a collaborative
and systematic approach and this is the case for
the development of biomarkers in both human
and veterinary medicine (Kondo, 2014). Techni-
cal challenges such as low sensitivity, reproduc-
ibility and throughput have caused biomarker
failures, but this has increasingly been overcome
by use of DNA microarray technology that
enables the measurement of the mRNA levels of
thousands of genes in a quantitative and repro-
ducible manner at relatively low cost (Kondo,
2014).
Market failure is another important chal-
lenge facing the development of new TB diag-
nostics like biomarkers. In the case of human
TB, industry usually avoids developing and mar-
keting products that will be mainly used by
patients in resource-limited countries because
such products do not generate profits (Wallis
et al., 2010). In addition, even if the products are
available, neither their cost nor performance are
adapted for developing countries, meaning that
their potential benefits are unavailable to the
patients and healthcare providers who need
them most (Wallis et al., 2010). For bovine TB,
major strides have been made and the coming
together of the bovine TB vaccine development
programme with the international human TB
vaccine programme has been beneficial and has
led to development of platforms with DIVA capa-
bility to be applied in countries that plan to use
vaccination together with test-and-slaughter
(Vordermeier et al., 2016b). The steps taken for a
biomarker to be approved as a diagnostic test are
rigorous before they can be approved for animal
or human use (Pesch et al., 2014).- 9 Conclusions
For global bovine TB control to become a reality,
there is need for a more accurate, affordable
point-of-care diagnostic test. Biomarkers are key
in this process, but it is important for researchers
to harness the advantages of having multiple
biomarkers. The bovine TB diagnostics pipeline
has grown in recent years with many promising
candidates. Biomarkers are among such candi-
dates but there is need for improvements in
standardization and validation procedures to
increase reproducibility and accuracy and pro-
mote adoption of these biomarkers. Continuous
improvement in our knowledge of these intrigu-
ing organisms is the best way of overcoming
some of the knowledge gaps surrounding TB bio-
markers. Knowledge about the biology of MTC
organisms and their host–pathogen interactions
is still incomplete thus research into these areas
will greatly enhance the development of accu-
rate, and safe biomarkers for bovine TB.ReferencesAbd-el-Fattah, A.A., Sadik, N.A., Shaker, O.G. and Aboulftouh, M.L. (2013) Differential microRNAs expres-
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