Table 3.

Summary of Studies Implicating HERVs in Autoimmune Rheumatic Disease and Molecular Techniques Used in Each

Disease	HERV	Study	Molecular Technique	Significance/Result
RA	HTLV-1 p19 and HIV p24 antigens	Ziegler et al. [35, 36]	Western blot, ELISA	45-55% patients expressed HTLV-1 antigen in synovial tissue, without serological HTLV-1 infection
	HERV-K10	Nelson et al. [31]	Quantitative RT-PCR	Significant association of sequence homology between HERVs and autoimmune rheumatic diseases
	HERV-K10	Reynier et al. [13]	NASBA	HERV-K detected in plasma of RA patients, with higher levels observed for those with active disease.
	HERV-K10	Ejtehadi et al. [46]	Multiplex RT-PCR	Enhanced expression of HERV-K10 in RA
	HERV-K10 HERV-W (MSRV) ERV-9	Nakagawa et al. [49]	RT-PCR	Multiple HERVs were expressed in normal and diseased synovium
	HERV-K10	Friemanis et al. [17]	Quantitative RT-PCR, ELISA	RA patients exhibited significantly elevated levels of HERV-K gag activity compared to controls
	HERV-K113	Krzysztalowska-Wawrzyniak et al. [47]	PCR	Significantly increased prevalence of HERV-K113 in patients with SLE and RA
SLE	HRES-1	Banki et al. [39]	Western blot, ELISA	Sera from patients with autoimmune disease had increased HRES-1 peptide binding activity than controls.
	HRES-1	Perl et al. [63]	Western blot, ELISA	Autoantibodies to HRES-1 found in autoimmune disease, especially if Ro / La negative.
	HRES-1	Pullman et al. [69]	Southern blot, PCR	The HRES-1 locus at the 1q42 chromosomal region influences SLE development and disease manifestations
	HIAP-1	Deas et al. [72]	Polyacrylamide gel electrophoresis (PAGE)	Cells exposed to HIAP-1 may be protected from apoptosis.
	HTLV-1 p19 and HIV p24 antigens	Talal et al. [37-38]	Western blot	Antibodies to p24 gag of HIV-1 found in absence of HIV-1 infection. Anti-Sm antibodies can cross-react with p24 gag.
	ERV-3	Li et al. [30]	Western blot, ELISA	ERV-3 may have a role in the pathogenesis of neonatal congenital heart block.
JIA	HERV-K18	Sicat et al. [82]	Semi-quantitative RT-PCR	HERV-K18 levels elevated suggesting a mechanism for autoimmunity by superantigen stimulation of auto-reactive T cells.
SJS	HIAP-1	Garry et al. [73]	PCR	HIAP-1 detected in cells exposed to salivary tissue from patients with Sjögren's syndrome.
	HRES-1	Brookes et al. [40]	Northern blot, ELISA	Significantly elevated levels of antibodies to HTLV-1 were found in several diseases.
	HERV-E env protein (λ4-1)	Hishikawa et al. [96]	Western blot	Anti-p30gag antibodies detected in sera of several diseases