GSH from hatcheries often develop reproductive problems and it is genetically transmitted.


Journal of Aquatic Animal Health

Volume 20, 2008 - Issue 1

Vertical Transmission of Ovipleistophora ovariae (Microspora) within the Eggs of the Golden Shiner

Nicholas B. D. Phelps & Andrew E. Goodwin

Fertilized eggs collected from broodfish infected by Ovipleistophora ovariae were tested by quantitative polymerase chain reaction (PCR) and found to be positive for the O. ovariae genome at 7.77 × 102 to 3.26 × 107 copies per microgram of host DNA. Fry hatched from these eggs contained from 1.37 × 102 to 9.89 × 106 copies of the O. ovariae genome per microgram of host DNA. Surface treatments of fertilized eggs with 150 mg formalin/L (used by farms as a fungicide) or a 1.5% solution of sodium sulfite (which removes the adhesive egg matrix) did not reduce vertical transmission to fry. Treatment of eggs with a 10% solution of bleach or a proprietary commercial DNA denaturant did not reduce the number of egg-associated copies of the O. ovariae genome. Histology of ovaries of infected fish demonstrated spores within the oocytes. However, no spores were observed by histology in positive fry hatched from infected eggs. The PCR and histological demonstration of the presence of O. ovariae spores in oocytes and fry, and the failure of strong DNA denaturants to reduce egg-associated copies, give evidence that O. ovariae is vertically transmitted within eggs.


Our demonstration of high copy numbers of the O. ovariae genome in golden shiner eggs and fry from infected broodfish shows that the parasite is vertically transmitted. Histology of ovaries sampled from broodstock showed very high densities of spores within oocytes and, together with the positive PCR results from progeny posthatch, demonstrate that the infected eggs remain viable and that the spores are incorporated into the fry. Intact spores were not detected in fry by histology, so it is likely that the spores germinate and infect host cells within the earliest phases of larval development. In an earlier report (Phelps and Goodwin 2007 Phelps, N. B. D. and Goodwin, A. E. 2007. Validation of a quantitative PCR diagnostic method for the detection of the microsporidian Ovipleistophora ovariae in cyprinid fishes. Diseases of Aquatic Organisms, 76: 215–221. ), we showed that male broodfish test positive for O. ovariae by qPCR, but not by histology. This may be the result of early development of the parasite in the testes that is later arrested at a prespore stage, when the gonad begins to differentiate into a testis rather than an ovary.

Last edited by ewest; 09/15/18 08:31 AM.