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Effect Of Temperature And Relative Humidity On The Survival Of Newcastle Disease Virus Isolates Using Germ Carrier Techniques

by Tayyeba Sohail (2009-VA-209) | Dr. Jawad Nazir | Prof. Dr. Khushi Muhammad) | Prof. Dr. Asim Aslam.

Material type: book Book; Literary form: not fiction Publisher: 2015Dissertation note: Newcastle Disease (ND) is a highly contagious viral disease that affects almost all avian species including poultry, cage and wild birds around the globe (Terregino et al. 2003; Vidanovic et al. 2011). ND is economically important disease and included as list-A disease of Office des International Epizootics (OIE) (Anonymous). Mortality of infected birds ranges from negligible to as high as 100 % depending on the pathotype of the virus involved and health status of the birds (Alexander and Manvell 2004). NDV is an enveloped virus with single stranded, non-segmented, negative sense RNA genome (Makoui et al. 2013). The virus belongs to Avulavirus genus of Paramyxoviridae. There exist only one serotype of NDV designated as avian paramyxovirus-1 (Kapczynski et al. 2013) however, different virus strains do vary in their pathogenicity. There are 3 pathotypes of NDV; velogenic (highly virulent), mesogenic (moderate virulent), and lentogenic (mild virulent) based upon diseases producing potential and severity of signs in the infected birds (de Leeuw and Peeters 1999). NDV is primarily transmitted to the susceptible birds through aerosol and fecal oral route (Martin 1992). Infected birds secrete high amount of the virus in their feces, saliva, mucous and nasal secretions which might contaminate the premises. Inanimate objects or fomites are a potential reservoir of viruses outside the host and might play an important role in the transmission of pathogens (Nicas and Sun 2006). Several factors can influence the survival of viruses outside the host (Sobsey and Meschke 2003; Weber and Stilianakis 2008; Stallknecht and Brown 2009). A number of studies show that respiratory pathogens can survive from hours to months on fomites (Abad et al. 2001; Kramer et al. 2006). Certain physical factors like temperature, humidity, pH, salinity, exposure to ultraviolet (UV) rays etc drastically affects the Introduction 2 virus persistence in the environment. Effect of such physical insults is more pronounced on enveloped viruses than non-enveloped ones (Mbithi et al. 1991; Schaap et al. 2012; Tuladhar et al. 2012). High humidity and temperatures not only reduces the survival of influenza viruses on contaminated surfaces but also modulates their transmission to the susceptible birds (Shaman and Kohn 2009; McDevitt et al. 2010; Paynter 2014). Similarly lower temperature and less humidity promote the survival of NDV in the environment (Dat and Chuc 1985; Kournikakis et al. 1988). ND is endemic in Pakistan but since last few years several new virus strains are circulating in commercial and rural poultry of the country (Munir et al. 2012; Shabbir et al. 2013). Central Punjab region is densely populated with commercial poultry and serve as disease epicenter every year. It has been observed that the disease outbreaks usually start in December, attain peak in the late winter and spring season, start decline in June and disappear in the rainy season. Apart from several other contributing factors, environmental survival of the viruses might contribute to the disease outbreaks. Availability: Items available for loan: UVAS Library [Call number: 2227-T] (1).

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In Process Quality Control Factors Affecting The Quality Of Locally Prepared Salmonella Gallinarum Antigen

by Zahra Malik (2009-VA-245) | Dr. Arfan Ahmad | Prof. Dr. Aftab Ahmad Anjum | Prof. Dr. Asim Aslam.

Material type: book Book; Literary form: not fiction Publisher: 2015Dissertation note: Fowl typhoid is a septicaemic disease caused by S. gallinarum biovar gallinarum has major economic significance in many parts of the world. It is an acute or chronic septicaemic disease that usually affects the birds (mostly adult birds). Eradication of disease is normally done by identifying the infected flocks and eliminating the reactor birds by using serological tests, but diagnosis of the disease is much expensive because antigen used for this purpose is imported. The study, therefore, has been proposed to prepare and evaluate the stained antigen of S. gallinarum using local isolates. A total of 15 isolates were procured from Poultry Research Institute (PRI) Rawalpindi, University Diagnostic Lab (UDL) and Department of Microbiology, UVAS Lahore, which were identified by Biochemical testing and further confirmed by Polymerase Chain Reaction. Among all 15 isolates two isolates were confirmed as S. gallinarum and proceeded to prepare local antigen of S. gallinarum. Locally prepared antigen was checked with known positive and negative sera, Effect of different preservatives (Sodium azide and Thiomersal sodium) and different storage temperatures (4°C, 25°C and -20°C) was also studied after every fifteen days post storage upto 6 months to observe the stability and shelf life of local antigen. On the end of study both preservatives i.e. Sodium azide and Thiomersal sodium was found equally effective for antigen activity, whereas 4°C proved best storage temperature to be used for the antigen preservation. Activity of locally prepared antigens was also compared with the imported antigen (Charles, River, USA) stored at different temperatures regularly throughout the six months, which showed that local antigens was almost as good as the imported antigen. Summary 51 CONCLUSION Locally prepared S. gallinarum antigen was found as effective as imported antigen. Both the test preservatives (Sodium azide and Thiomersal Sodium) had the same effect on antigen preservation. Among all three test temperatures, 4°C was accepted as best storage temperature for the long term preservation of local antigen with either of the preservative. Availability: Items available for loan: UVAS Library [Call number: 2278-T] (1).

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