I've had a quick look at these five studies, and most of them don't tell us anything new... Only the Retrovirology study by Hue et al seems to bring up significant new research findings.
This one, by Sato et al, tests a commercial PCR kit, and finds contamination by mouse DNA...
http://www.retrovirology.com/content/pdf/1742-4690-7-110.pdf
But they do not find XMRV or Alter's PMRV, only similar endogenous mouse retroviruses...
Alter tested for mouse viruses and mouse DNA, and I assume that Judy has as well, although i can't remember if she has.
This study doesn't tell us much new... Just that researchers need to eliminate mouse viruses from any findings they make.
This one, by Oakes et al (includes Huber and Coffin), is old news, and just confirms that they detected mouse contamination, and it warns researchers to always check for mouse DNA and mouse viruses...
http://www.retrovirology.com/content/pdf/1742-4690-7-109.pdf
This one, by Robinson et al (inludes McClure and Coffin) (Coffin's name seems to popping up a lot!), is similar to Huber's paper, in that it recommends that researchers always check for mouse contamination.
http://www.retrovirology.com/content/pdf/1742-4690-7-108.pdf
This one by Smith, seems to be purely a commentary on the Retrovirology paper by Hue et al (see below)...
http://www.retrovirology.com/content/pdf/1742-4690-7-112.pdf
This one, by Hue et al, is the most significant paper and demands closer inspection... It's the only paper of the five that has the potential to challenge the findings to date (it actually seems quite refreshing to have a serious contamination challenge for a change)... I'll have a close look at it later... I don't know how the science stands up without reading it carefully.
http://www.retrovirology.com/content/pdf/1742-4690-7-111.pdf
The conclusion to the paper does not seem to be as conclusive as the commentaries are reporting it, and the paper does not appear to address the issue of human anti-bodies to XMRV.
Disease-associated XMRV sequences are consistent with laboratory contamination
Conclusions
We provide several independent lines of evidence that XMRV detected by sensitive PCR methods in patient samples is the likely result of PCR contamination with mouse DNA and that the described clones of XMRV arose from the tumour cell line 22Rv1, which was probably infected with XMRV during xenografting in mice. We propose that XMRV might not be a genuine human pathogen.
http://www.retrovirology.com/content/7/1/111