Induction of Long-Term Protective Immune Responses by Influenza H5N1 Virus-Like Particles

Recurrent outbreaks of highly pathogenic H5N1 avian influenza virus pose a threat of eventually causing a pandemic. Early vaccination of the population would be the single most effective measure for the control of an emerging influenza pandemic.Influenza virus-like particles (VLPs) produced in insect cell-culture substrates do not depend on the availability of fertile eggs for vaccine manufacturing. We produced VLPs containing influenza A/Viet Nam1203/04 (H5N1) hemagglutinin, neuraminidase, and matrix proteins, and investigated their preclinical immunogenicity and protective efficacy. Mice immunized intranasally with H5N1 VLPs developed high levels of H5N1 specific antibodies and were 100% protected against a high dose of homologous H5N1 virus infection at 30 weeks after immunization. Protection is likely to be correlated with humoral and cellular immunologic memory at systemic and mucosal sites as evidenced by rapid anamnestic responses to re-stimulation with viral antigen in vivo and in vitro.These results provide support for clinical evaluation of H5N1 VLP vaccination as a public health intervention to mitigate a possible pandemic of H5N1 influenza

Factors affecting the reproductive performance of Awassi sheep flocks in north-east of Jordan : an epidemiological study

A prospective cohort study was conducted using 32 randomly selected Awassi sheep flocks to identify factors hypothesized to be associated with the occurrence of pregnancy, twinning and fetal loss between August 2005 and May 2006 in the region of Al-Safawi (northeast of Jordan). Vitamins A and E and selenium concentrations were determined on 448 blood samples. Using the forward selection procedure of the logistic regression module, models with statistically significant risk factors (P < 0.05) were constructed for three outcomes; pregnancy, twinning and fetal loss. Serum vitamin A concentration levels were associated with pregnancy (OR = 2.26, 2.48), twinning (OR = 6.49, 17.74) and fetal loss (OR = 0.13, 0.19). Primiparous ewes were 48% less likely to become pregnant than fourth or higher parity ewes. The likelihood of twinning increased significantly in ewes up to the third parity. Ewes that were fed 700-900 g barley, 250-300 g wheat-bran per head per day and grazed on vegetables residues were 4.15 times more likely to have twins than ewes that were fed 600 g barley and 200 g wheat-bran per head per day. Fetal loss in first and second parity ewes was about 3 times more likely than that in third or higher-parity ewes. Ewes pregnant with twins were about 14 times more likely to have fetal loss than ewes carrying single fetus. Pregnant ewes of the stationary flocks were 37% less likely to have fetal loss than ewes of the semi-nomadic flocks. These results demonstrate that stationary Awassi sheep flocks had higher pregnancy and twinning rates and less pregnancy loss. Supplementation of vitamin A, providing sufficient quantity of dry feed and increasing ram: ewe ratio for primiparous ewes of semi-nomadic flocks is essential to improve Awassi sheep reproductive performance.S. Q. Lafi, A. Q. Talafha, N. Giadinis, E. Kalaitzakis, K. Pourliotis, N. Panousi