Retrospective evaluation of the immunoreactivity of viral antigens after several years of "formalin" fixation at ambient temperature: a rabies virus-immunoperoxidase model
Torres-Anjel, M.J.; Blenden, D.C.; Frost, J.W.; Raisbeck, M.; Oakman, J.K.; Volz, D.
Revista Latinoamericana de Microbiologia 29(4): 337-344
1987
ISSN/ISBN: 0187-4640 PMID: 3334105 Document Number: 293330
Histopathological diagnosis on both light and electron microscopy is extremely dependent on (form-, paraform-, glutar-) aldehyde fixation of specimens. Aldehyde treatment guarantees no risk of contamination and indefinite maintenance of specimens. The basis of this paper was our recent success with an immunoperoxidase (IP), peroxidase-anti-peroxidase (PAP) or IPP retrospective ("blind" study) immunostaining of 119 formalin treated specimens (wet samples, embedded blocks, mounted slides) kept for at least 48 months at R.degree.C after transporting them internationally. Most samples were buffered-formalin fixed; a few were unbuffered. No enzyme awakening was applied. The pH of the fluid fixative in the samples was studied. The pH showed a compatible normal like distribution with a mean .+-. standard deviation of 5.66 .+-. 0.66. The pH did not relate with the quality of the reading. All primary antibodies were polyclonal whole sera produced in the rabbit against purified nucleocapsid and/or semipurified whole viron (commercial vaccine origin). Readings when compared (blindly) with the technique traditional fluorescent antibody (FA) in the fresh samples gave 95+% co-positivity ("sensitivity") and 94% conegativity ("sensitivity") with only 7 crossover data (four false +. three false-), 6/7 with an unusual history behind them. Although our results were with rabies virus (a fastidious antigen anyway), the findings may stimulate applications to other rhabdo, RNA, and other viruses, and maybe to other antigens/agents/immunogens.