|Byrd, James - Allen|
|Nisbet, David - Dave|
Submitted to: Journal of Veterinary Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2005
Publication Date: 6/15/2005
Citation: Howard, Z.R., Moore, R.W., Zabala-Diaz, I.B., Landers, K.L., Byrd Ii, J.A., Kubena, L.F., Nisbet, D.J., Birkhold, S.G., Ricke, S.C. 2005. Ovarian laying hen follicular maturation and in vitro salmonella internalization. Journal of Veterinary Medicine. (108):95-100. Interpretive Summary: Ovarian follicle infection by Salmonella enteritidis and Salmonella Typhimurium was investigated using an ovarian tissue culture. The ovarian follicles at different stages of maturity were collected from adult white Leghorn hens. The follicles were incubated with Salmonella for 2 hours. After allowing the Salmonella to infect the ovarian follicle, the Salmonella which had not penetrated the follicle was removed with an antibiotic. The amount of Salmonella which had penetrated the follicle was then counted. The data suggests that the less mature small white follicles may be more susceptible to Salmonella infection than the more mature small yellow and large yellow follicles. By better understanding the mechanisms involved in Salmonella infection, we may be able to help to prevent Salmonella infections of the ovaries of laying hens.
Technical Abstract: Transovarian transmission of paratyphoid Salmonella is well documented and occurs at a low incidence in chickens. However, the exact mechanism of follicular invasion is not well understood. The following study investigates the ability of Salmonella to invade ovarian follicles at different stages of follicular maturity in vitro. Ovarian follicles were collected from Leghorn hens and separated into three stages of maturity: 1) large yellow follicles or F follicles (LYF), 2) small yellow follicles (SYF), and 3) small white follicles (SWF). All follicles were incubated at 37°C in RPMI 1640 medium. Follicles were incubated with 1,000,000 CFU/mL of Salmonella Typhimurium and Salmonella Enteritidis sensitive to gentamicin for 2 h. Samples were then removed from the bacterial culture, and placed in medium containing gentamicin sulfate for 5 h to kill any S. Typhimurium or S. Enteritidis which had not invaded the follicular membrane. After the 5 h incubation, follicles were stomached in phosphate buffered saline. Serial dilutions were made of each follicle and viable S. Typhimurium and S. Enteritidis cells were enumerated on brilliant green agar. Two identical trials were conducted. Data suggest that Salmonella may differentially invade ovarian follicles depending on maturity of the follicle, and that SWF may be more susceptible to S. Typhimurium and S. Enteritidis invasion than either the SYF or the LYF.