Risk Assessment of Minute Virus of Mice Transmission During Rederivation: Detection in Reproductive Organs, Gametes, and Embryos of Mice after In Vivo Infection1

Abstract

Murine parvoviruses, including minute virus of mice (MVM), represent major infectious disease problems encountered in contemporary laboratory animal research facilities with embryo transfer (ET), one of the most widely used techniques for rederivation. Using an in vivo approach, the objectives of this study were to assess the risk of MVM transmission during rederivation and to provide data that allow recommendation of preventive measures. Therefore, we determined whether immunosuppressive variant MVMi viral DNA is detectable in reproductive organs, gametes (oocytes and spermatozoa), and embryos collected from experimentally infected mice and whether washing as recommended before ET eliminates MVMi sufficiently from gametes and embryos. Fractions of reproductive organs tested positive from Day 5 to Day 30 postinoculation, demonstrating a risk for a minimum period of 4 wk; the highest incidence of positive organs was found between Day 9 and Day 13 postinoculation. Real-time PCR detected viral DNA to a lesser extent in male than in female reproductive organs. MVMi DNA was detected in oocytes and sperm cells derived after in vivo infection but not in two-cell embryos. In vitro contamination studies revealed that the virus firmly adheres to the zona pellucida after 10 wash steps, indicating that even extensive washing might not eliminate MVMi completely from embryos. According to this systematic in vivo approach, recommended measures to prevent transmission of MVM during rederivation include sufficient washing of embryos, accompanying testing using adequate (PCR) methods, and using embryos rather than in vitro fertilization techniques; furthermore, the exchange of gametes should be considered a risk factor.

Decontamination of genetically modified mice strains by embryo transfer for obtaining SPF colonies in a Brazilian animal facility

“…In this regard, biosecurity measures preconized by the International Embryo Technology Society (IETS) and by the World Organisation for Animal Health (OIE) must be correctly followed (Stringfellow, 1998;Stringfellow & Givens, 2000; World Organisation for Animal Health, 2016). 962/121 (51) 2 17/40 (43) B6 CD11c-YFP (5) 15/44 (34) 1 8/15 (53) B6 OT II (5) 27/51 (53) 1 11/20 (55) 129 Sv PKR 568/103 (66) 2 15/40 (38) B6 PUMA 49/14 (64) 1 6/9 (67) B6 CD45.1 334/42 (81) 1 13/20 (65) B6 ATG7RosaCreR 529/54 (54) 1 8/20 (40) B6 Bim 648/118 (41) 2 12/40 (30) B6 Dectin-1 458/91 (64) 2 5/40 (13) B6 lpr 735/109 (32) 2 5/35 (14) B6 PAFR 12123/245 (50) 3 3/60 (5) B6 TLR-4 339/75 (52) 2 5/39 (13) B6 Galectina 566/95 (69) 1 5/20 (25) B6 XPC 733/67 (49) 2 0/33 (0) B6 P2RX7 328/53 (53) 2 3/28 (11) B6 Perforina 434/44 (77) 2 10/34 (29) K14-64/CSA 553/89 (60) 3 0/53 (0) K14-64 (+) /XPC (-/-) 57/77 (9) 1 3/7 (43) B6 Caspase 561/113 (54) 1 11/20 (55) B6 ASC 552/97 (54) 4 8/52 15Key: 1) Total number of embryos in two-cell, fragmented eggs and unfertilized oocytes. 2) Number of transferred embryos were performed accordingly to the number of recipients available.…”

“…Furthermore, rederivation of mouse strains by fresh embryo transfer has been reported to avoid vertical transmission of mouse diseases (Reetz et al, 1988). The risk of transmission of certain viruses by embryo transfer, such as murine parvoviruses, should always be considered, though this technique reduces the potential for the introduction of diseases into animal facilities (Janus et al, 2009).…”

Coping with parvovirus infections in mice: health surveillance and control

“…This hypothesis was supported by an in vivo approach where MVMi DNA was detected to a lesser extent in male than in female reproductive organs by realtime qPCR. 88 In this context the risk for transmission was determined to consist of a four-week minimum period as reproductive organs tested positive for MVMi DNA from day 5 post-inoculation up to day 30 post-inoculation. Even oocytes and sperm cells were found to be positive for MVMi DNA, but not two-cell embryos after in vivo infection and sufficient washing.…”

“…When IVF is performed, gametes should be derived after an at least four-week quarantine period of the donor, as the percentage of reproductive organs testing positive for MVM decreased towards the end of a 30-day period after experimental inoculation of mice. 88 Concerning the extensive exchange of genetically-modified mice in recent years, special regard should be given to the fact that the shipment of gametes, which has been proposed as an alternative to sending live mice, may be a potential source for the introduction of parvoviral disease into animal facilities. However, ET can be evaluated as an adequate method for re-derivation of mouse strains comprising a manageable risk of transferring parvoviruses if certain precautions such as careful washing and accompanying testing are minded, while the exchange of gametes should be considered as a risk factor.…”

Viral Infections of Laboratory Mice

“…The virus can be eliminated from infected breeding populations by caesarean derivation or by embryo transfer. However, certain precautions such as careful washing and accompanying testing need to be minded, as MVM has been detected in reproductive organs and gametes and this virus firmly attaches to the zona pellucida or might even cross it [210,211]. In experimental colonies, elimination of infected animals and subsequent replacement with uninfected mice is practical if careful environmental sanitation is conducted by appropriate disinfection procedures.…”