Ebola virus-like particles (VLPs) were produced in insect cells using a recombinant baculovirus expression system and their efficacy for protection against Ebola virus infection was investigated. Two immunizations with 50 ug Ebola VLPs (high dose) induced a high level of antibodies against Ebola GP that exhibited strong neutralizing activity against GP-mediated virus infection and conferred complete protection of vaccinated mice against lethal challenge by a high dose of mouse-adapted Ebola virus. In contrast, two immunizations with 10 ug Ebola VLPs (low dose) induced 5-fold lower levels of antibodies against GP and these mice were not protected against lethal Ebola virus challenge, similar to control mice that were immunized with 50 ug SIV Gag VLPs. However, the antibody response against GP were boosted significantly after a third immunization with 10 ug Ebola VLPs to similar levels as those induced by two immunizations with 50 ug Ebola VLPs, and vaccinated mice were also effectively protected against lethal Ebola virus challenge. Furthermore, serum viremia levels in protected mice were either below the level of detection or significantly lower compared to the viremia levels in control mice. These results show that effective protection can be achieved by immunization with Ebola VLPs produced in insect cells, which give high production yields, and lend further support to their development as an effective vaccine strategy against Ebola virus.

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The aim of this study was to determine the effect of prepartum somatotropin injection in late-pregnant Holstein heifers on metabolism, milk production and resumption of postpartum ovulation. For this study, 31 late-pregnant Holstein heifers were used. The heifers were assigned randomly into two treatments: (1) 500 mg sc injections of somatotropin (somatotropin treatment, n 5 15) at 235 and 221 days, and, if pertinent, at 27 days from expected calving date and (2) no treatment (control group, n 5 16). Blood samples were collected weekly from 25 to 7 weeks after calving. Heifers with progesterone concentrations in plasma above 1 ng/ml in two consecutive postpartum samples were considered as having resumed ovarian activity. A higher proportion (P 5 0.04) of heifers treated with somatotropin resumed ovarian activity in the first 7 weeks post partum (73.3%; 11/15) compared with the control group (37.5%; 6/16). A higher number (P 5 0.02) of heifers in the somatotropin treatment group also ovulated during the first postpartum follicular wave (53.3%; 8/15) compared with the control group (12.5%; 2/16), as indicated by the number of heifers ovulating in the first 3 weeks post partum. Pregnancy rate was not affected by treatments (P . 0.10) and averaged 40.0% (6/15) in somatotropin-treated and 25.0% (4/16) in control heifers when evaluated up to 150 days in milk. Somatotropin treatment increased the average daily milk production by 2.8 kg/cow per day (P , 0.0001) and reduced the somatic cell count (P 5 0.009). Plasma IGF-I was higher (P , 0.05) for somatotropin-treated heifers in the prepartum period. Insulin and body condition score were higher (P , 0.05) and non-esterified fatty acids were lower (P , 0.05) for somatotropin-treated cows in the early postpartum period. In conclusion, somatotropin injection during the prepartum period in late-pregnant Holstein heifers was able to increase the proportion of heifers resuming ovarian activity early post partum, inspite of higher milk production.Keywords: bST, dairy heifers, IGF-I, ovarian activity, primiparous ImplicationsPhysiological changes during the transition period can have a great impact on health and performance. In our study, prepartum injection of somatotropin reduced negative energy balance (NEB) intensity as indicated by several metabolic markers evaluated in the postpartum period. A more intense NEB is usually associated with a delay in resumption of normal ovarian function. In this way, we observed a higher proportion of somatotropin-treated heifers ovulating earlier.Moreover, cows treated with somatotropin prepartum increased milk production. Along with earlier resumption of estrous cycles, this strategy can have an important impact on farm profitability. IntroductionDuring the early postpartum period, high-producing cows experience a period of negative energy balance (NEB) that occurs as the requirements for milk production exceed the -E-mail: augusto.schneider@live.com 935 energy obtained through feeding (Butler, 2003). In early postpartum dairy cows, the du...

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