Puzzling inefficiency of H5N1 influenza vaccines in Egyptian poultry.

In Egypt, efforts to control highly pathogenic H5N1 avian influenza virus in poultry and in humans have failed despite increased biosecurity, quarantine, and vaccination at poultry farms. The ongoing circulation of HP H5N1 avian influenza in Egypt has caused >100 human infections and remains an unresolved threat to veterinary and public health. Here, we describe that the failure of commercially available H5 poultry vaccines in Egypt may be caused in part by the passive transfer of maternal H5N1 antibodies to chicks, inhibiting their immune response to vaccination. We propose that the induction of a protective immune response to H5N1 is suppressed for an extended period in young chickens. This issue, among others, must be resolved and additional steps must be taken before the outbreaks in Egypt can be controlled.

Do commercial avian influenza H5 vaccines induce cross-reactive antibodies against contemporary H5N1 viruses in Egypt?

After emerging in Egypt in 2006, highly pathogenic avian influenza H5N1 viruses continued to cause outbreaks in Egyptian poultry and sporadic human infections. The strategy used by Egyptian authorities relied on vaccinating poultry, depopulating infected areas, and increasing awareness and biosecurity levels. Despite those efforts, H5N1 became endemic, and vaccine-escape variants are thought to have emerged even though commercial poultry vaccines were protective in laboratory settings. We studied the cross-reactivity of 6 commercially available H5 poultry vaccines against recent H5N1 Egyptian isolates in a field setting in Egypt. Only one vaccine based on an Egyptian H5N1 virus induced high cross-reactive antibody titers. Our results may be explained by the fact that the seed viruses in these vaccines are genetically distinct from H5N1 viruses currently circulating in Egypt. In light of our findings, we recommend that the H5N1 prevention and control strategy in Egypt be updated and reinforced. Special consideration should be given to the vaccination strategy, and the use of vaccines based on currently circulating viruses is advisable.

Effects of Mirazid(®) and myrrh volatile oil on adult Fasciola gigantica under laboratory conditions.

OBJECTIVE: To evaluate the effects of Mirazid(®) and myrrh volatile oil on adult Fasciola gigantica (F. gigantica ) under laboratory conditions. METHODS: The effects of oleoresin extract of myrrh (Mirazid(®)) and myrrh volatile oil on the surface morphology of adult F. gigantica following treatment in vitro had been determined by scanning electron microscopy. The results were compared with those observed in the fluke tegument following incubation in triclabendazole sulphoxide (TCBZ-SO), active form, (Fasinex(®), Ciba-Geigy). RESULTS: Observations of the efficacy of Mirazid(®) oleoresin extract and myrrh volatile oil indicated that both products showed dose-dependent anthelmintic efficacy. The anterior half of the fluke was consistently more severely affected than the posterior half. The surface changes induced by Mirazid(®) oleoresin extract were less severe than those observed after exposure to either myrrh volatile oil or TCBZ-SO. Flukes showed swelling after these treatments, but its level and blebbing were much greater with myrrh volatile oil; in which patches of tegumental sloughing were observed in the apical cone and the posterior mid-body region of flukes. This was not observed after treatment with Mirazid(®) oleoresin extract. CONCLUSIONS: The comparatively more disruption, observed in myrrh volatile oil exposed specimens, compared to that exposed to Mirazid(®) oleoresin extract might suggest that the anthelmintic activity of Mirazid(®) oleo resin extract was attributed to its content of volatile oil. So, increasing the concentration of myrrh volatile oil in Mirazid(®) might possibly help to developing its anthelmintic activity.

Characterization of an avian influenza virus H5N1 Egyptian isolate.

The highly pathogenic influenza virus H5N1 that infected chickens in Egypt in 2006 was characterized at immunologic and molecular levels. Cloacal swabs from chicken were analyzed by rapid antigen detection and RT-PCR using H5- and N1-specific primers, which confirmed the presence of an H5N1 influenza virus in infected chickens. Sequencing results revealed 100% homology of both genes with previously published sequences of H5N1 isolates from Egypt and the Middle East. The virus was isolated and propagated in MDBK cells in culture. Host cells showed a substantial cytopathic effect within 2 days of infection, which increased dramatically by the fourth day. Plaque infectivity titers of virus harvested from cell culture were initially 10(5)PFUs/ml and increased to 10(8)PFUs/ml after two additional passages and ultrafiltration. Formaldehyde treatment completely inactivated the virus, and MDBK cells inoculated with the killed virus showed no cytopathic effect. Two days after chickens were immunized with the killed virus, their sera showed that the killed Egyptian isolate was highly immunogenic. Western blot analysis showed that sera had antibodies reacting to four viral peptides: hemagglutinin (61.5kDa), RNA-binding protein (56kDa), neuraminidase (50kDa), and 45-kDa protein. In a challenge infection, the vaccine protected immunized chickens from death and reduced viral shedding.

Acaricidal efficacy of Myrrh (Commiphora molmol) on the fowl tick Argas persicus (Acari: Argasidae).

Five concentrations of purified extract of Myrrh from Commiphora molmol tree were prepared to study its effects on the fowl tick Argas persicus under laboratory conditions. The results revealed that Myrrh had dependant dose toxic effect on the adult female of A. persicus. Toxicity increased gradually daily post treatment. The LC50 was 1.28%, 0.88%, 0.84%, 0.50% and 0.42% at Ist, 2nd, 3rd, 6th and 12th days respectively. At 12th day, the recorded mortality rates were 63, 67, 76, 87 and 94% for concentrations, 0.625, 1.25, 2.5, 5 and 10%, respectively against 5% in control. Histopathological and Transmission election microscope (TEM) examinations showed the lysing of epithelial gut cells in treated groups. The lysed epithelial gut cells showed irregularly distributed nucleus, commonly at low concentrations and rarely in high concentrations of Myrrh. The lysed epithelial gut cells, without nucleus or with aggregated one beside the basal lamina, were common at high concentrations and rare in low concentrations of Myrrh. Consequently, Myrrh can rapidly penetrate the cuticle to body cavity, destroy the epithelial gut cells and finally cause the death of ticks.