A novel approach of producing positron emission tomography (PET) imaging agents through the formation of bioconjugates based on pegylation-fluorination strategy resulting in fluoro-pegylated (FPEG) molecules is reported. This approach offers a simple and easy method by which to incorporate 18

Hydropericardium syndrome (HPS) is a highly infectious disease caused by fowl adenovirus serotype 4 (FAV-4) affecting poultry, especially broiler birds. The disease was initially reported from Angara Goth, Pakistan, and then from India during 1994, in the poultry belt of Jammu and Kashmir, and thereafter, from almost all parts of the country, causing heavy economic losses to the poultry industry. The disease occurs predominantly in broilers of the age group of 3-5 weeks, characterized by sudden onset of high mortality up to 80 %. The causative agent of HPS is fowl adenovirus 4, which is a member of the species Fowl Adenovirus C, genus Aviadenovirus, family Adenoviridae [60]. FAV-4 is non-enveloped and icosahedral in shape, measuring 70-90 nm in size and containing a linear dsDNA of approximately 45 kb in size as its genome. The livers of affected birds show necrotic foci and basophilic intranuclear inclusion bodies in the hepatocytes. The disease can be diagnosed from its gross and microscopic changes in the liver and by various serological tests, such as agar gel immunodiffusion, counterimmunoelectrophoresis, indirect haemagglutination, fluorescent antibody techniques, and ELISA. In the past few years, PCR has been used as a rapid diagnostic tool for the detection of fowl adenoviruses. The disease has been brought under control by the use of formalin-inactivated, attenuated or live vaccines in experimentally infected birds. Advancement in the field of computational immunology accelerates knowledge acquisition and simultaneously reduces the time and effort involved in screening potential epitopes, leading toward the development of epitope-based vaccines.

| Contagious pustular dermatitis (CPD), also known as Orf or contagious ecthyma is an important viral disease of sheep and goats. It is mainly seen as a benign disease but malignant form has also been reported from few parts of the world. The rates of morbidity and mortality are higher, particularly in lambs and kids experiencing the disease for the first time. The causative agent of disease is Orf virus, type species of the genus Parapoxvirus belonging to family Poxviridae. The virus produces localized persistent proliferative skin lesions and affected hosts are infected repeatedly owing to its host immune evasive strategy. These viruses have been found uniformly labile to chloroform but resistant to ether and also exhibit antigenic variations among them. Clinically, the disease is enzootic and occurs in three forms viz. labial, genital / mammary and generalized forms. The incubation period in natural cases is 2-3 weeks. The disease outbreaks mostly occur between autumn and spring but its severity is more in autumn and winter than spring. The virus grows well in cell cultures of caprine, ovine and bovine origin. Confounding symptoms impose laboratory affirmation by serological assays or molecular techniques. The disease can be diagnosed by electron microscopy, serological tests and PCR/ quantitative real-time PCR. Virus specific antibody response to structural proteins of capripox and orf viruses in western-blot analysis readily differentiates these two infections. The antibody response to the 32 kDa and 26 kDa proteins of capripox viruses provides a firm basis for differentiation. Although, the role of humoral immunity is well established but probably cell mediated immunity plays a major role in recovery from natural infections. A number of inactivated and live or live modified vaccines have been tried with variable success. The duration of immunity after vaccination is controversial; outbreaks have occurred in vaccinated animals. The disease is also of public health significance as it causes infection in human beings. Keywords

Hydropericardium syndrome (HPS) in broiler birds of 3 to 6 weeks of age was recorded for the first time in the Haldwani area of Nainital district (UP) in India in November, 1994. The overall mortality in 6 poultry farms was 61.62 per cent. The disease was experimentally transmitted by bacteria free infected liver homogenate extract passed through membrane filters of 0.22 and 0.1 mu APD. The aetiological agent was inactivated by heat treatment at 56 degrees C for one hour and 80 degrees C for 10 min. A precipitin band was demonstrated in agar gel immunodiffusion and counter immunoelectrophoresis using infected liver homogenate extract as antigen and homologous antisera raised in the laboratory. The disease was effectively controlled by formalinised and heat inactivated autogenous vaccine prepared from the infected livers of birds which died of natural infection.

A series of 18F fluoropegylated diphenylacetylenes as probes for binding to Abeta plaques were successfully prepared. These relatively rigid acetylenes, 12a, 12b, 14a, and 14b, displayed high binding affinities in postmortem AD brain homogenates (Ki ranging from 1.2 to 2.9 nM). In vivo biodistribution in normal mice exhibited excellent initial brain penetrations (4.42, 4.55, 5.41, and 6.78% dose/g at 2 min for [18F]12a, 12b, 14a, and 14b, respectively). [18F]12b and [18F]14b, with a longer fluoropegylated unit, that is, n=3, showed faster brain washout at 30 min postinjection (0.42 and 1.57% dose/g) as compared to the shorter fluoropegylated chain ligands, that is, [18F]12a and [18F]14a (1.03 and 3.69% dose/g). Autoradiography and homogenate binding confirmed the high binding signal due to Abeta plaques. These preliminary results suggest that the novel diphenylacetylenes may be potentially useful for imaging of Abeta plaques in the brain of patients with Alzheimer's disease.