Utilization of protein-A in immuno-histochemical techniques for detection of Peste des Petits Ruminants (PPR) virus antigens in tissues of experimentally infected goats

This paper constitutes the first record of utilizing the S. aureus protein-A (PA), conjugated to peroxidase enzyme, for the detection of the Peste des Petits Ruminants (PPR) virus antigens in tissues of experimentally infected goats. The goats were experimentally infected with a virulent PPR virus, which was previously isolated from a severe natural disease outbreak in gazelles, during 2002 in Saudi Arabia. The technique is rapid, and has the superiority over the peroxidase –anti-peroxidase (PAP) test in that, inactivation of the indigenous peroxidase in the tissues is not required and that it can be used against a wide range of animal species. An advantage over the other immunolabelled conjugates is that PA attaches specifically to the crystalizable fraction (Fc) of the IgG molecule, thus allowing the antigen binding fraction (Fab) of the molecule, free to interact specifically with the antigen. So, it doesn't actually compete with the antigen for the Fab portion of the IgG molecule. In the present study, PA conjugate detected the PPR virus antigens in various tissues of the experimentally infected goats.     

Pathology and molecular diagnosis of paratuberculosis of camels

Camels are the prime source of meat and milk in many desert regions of the world including Saudi Arabia. Paratuberculosis of camels, locally called Silag, is a serious and invariably fatal disease in the Arabian camel. Six camels were used in this study. Five camels with clinical paratuberculosis were used to study the pathology of the disease and confirm its aetiology. The sixth camel was clinically healthy and used as a control. The camels were examined clinically and bled for haematological and blood chemistry analysis. They were then humanely killed with a high intravenous dose of thiopental sodium (10 mg/kg) for pathological studies as well as obtaining tissues for microbiological and molecular studies. The clinical signs of the disease were emaciation, diarrhoea, alopecia, wry neck and pale mucous membranes. Laboratory diagnosis showed reduced haemoglobin concentration, low haematocrit and high activity of the serum enzyme alanine aminotransferase. Serum creatinine concentration was normal. These results indicated the infected camels were anaemic and the function of their livers was affected. Postmortem examination showed thickened and corrugated intestinal mucosa, enlarged granulomatous mesenteric lymph nodes, miliary and diffuse granulomas in the liver (in four camels), generalized lymph node granulomas (in one camel), splenic granuloma (in one camel) and mediastinal lymph node granuloma (in two camels). Histopathological examination showed diffuse infiltration of macrophages in all organs showing lesions. Ziehl–Neelsen staining of tissue scraping and tissue sections showed masses of acid fast bacilli, except for the spleen. Infection with Mycobacterium avium subsp. paratuberculosis was confirmed by PCR by targeting the IS900 gene.     

Use of pulse trickles to reduce clogging problems in trickle irrigation system in Saudi Arabia

Laboratory experiments were conducted at the Agricultural and Veterinary Training and Research Station, King Faisal University, Al-Hassa, Kingdom of Saudi Arabia to study the effect of pulse irrigation from a line source on sandy soil uniformly packed in soil tank using high flow rates. It was found that the increase in pulsed flows up to six times to that of the equivalent continuous flow can be used with little change to the soil wetting pattern. The water deep percolation reduced and horizontal spread increased with an increase in the pulsed flow up to twelve times to that of continuous flow (control treatment). A strong correlation was obtained between the water application rates and the vertical and horizontal advances which could be expressed as power function. The results showed an excellent potential to increase the emitter sizes up to 2.4-3.5 times and the emitter cross section area up to 6.0-12.0 times than the normal size for reducing the trickle clogging problem. Empirical analysis of the vertical and horizontal advance shows that both of these parameters can be expressed as a power function.     

Recovery and molecular characterization of live Camelpox virus from skin 12 months after onset of clinical signs reveals possible mechanism of virus persistence in herds

Potentially pathogenic orthopoxviruses (OPVs) persist in nature and re-emerge for reasons we do not fully understand. New information pertaining to Orthopoxvirus (OPV) persistence in nature would significantly improve surveillance and control programs. In a recent investigation of a Camelpox virus (CMLV) outbreak in Eastern Saudi Arabia, atypical minute pox-like skin lesions (AMPL) persisted on 42.9% of convalescent camels (8.8% of herd) for more than a year after the onset of clinical signs. In order to investigate whether AMPL were related to CMLV infection, AMPL homogenates were inoculated on the chorioallantoic membranes (CAM) of specific-pathogen-free (SPF) embryonating chicken eggs (ECE). Live CMLV was recovered from AMPL homogenates. The sequences of the ATIP gene of viruses isolated in the beginning of the outbreak, and one year later from AMPL were identical, and similar to the Kazakhstan isolate CMLV M-96. Virus identity was confirmed by sequence analysis of the CMLV A33R, A27L, B5R, and L1R orthologue genes. Uninfected adult camels that came in contact with animals showing AMPL became infected within two weeks. Since AMPL were easily missed by veterinarians and camel drivers, it was concluded that CMLV survival in persistent skin lesions may be a key mechanism in maintaining the virus in previously infected camel herds during inter-epizootic periods.     

Seroepidemiological study of Rift Valley fever (RVF) in animals in Saudi Arabia

Serological prevalence of IgG antibodies against Rift Valley fever (RVFV) virus was investigated in 22 major localities in five different regions of Saudi Arabia where vaccination against RVF virus (RVFV) is not practiced. The study excludes the southwestern region where a major outbreak of RVF occurred in 2000 and where annual vaccination of ruminants is practiced. Sheep and goat IgG-sandwich ELISA were used to test serum samples from sheep and goats, and bovine IgG-sandwich ELISA was used to test cattle sera. A nonspecies-specific, nonantibody isotype-specific ELISA was used to test camel sera. A total of 3,480 sheep, goats, cattle and camels with no previous history of vaccination against RVFV were randomly tested. All tested animals were negative for IgG class antibodies against the virus except four out of 1,508 sheep and three out of 913 goats, which tested positive. All animals were clinically normal and no evidence was found of virus activity in the studied areas. It is, therefore, most likely that those rare positive cases, which constituted 0.002% of the total animals tested, were either false positives or vaccinates smuggled from the outbreak zone. The need for regular monitoring of animals both within the outbreak zone of 2000 and other parts of the kingdom is strongly emphasized.     

Hydrochemical processes and metal composition of Ain Umm-Sabah natural spring in Al-Hassa Oasis Eastern Province, Saudi Arabia

This study was carried out to determine the hydro-chemical processes and the metal concentration of spring water to evaluate its suitability for irrigation and other purposes. A total of 10 water samples were collected from Ain Umm Sabah at different times and from different locations from the spring basin. EC (dS m(-1)), pH, temperature, total cations (Na, Ca, Mg, K) and anions [Cl, CO3, HCO3, SO4, NO3, Fluoride (F)] were determined. Some trace and heavy metals (Al, As, Ba, B, Br, Mo, Ni, Si, Cd, Cu, V, Fe, I, Pb, Mn, Zn, Sr, Se, Sb, La and Se were determined. The Spring water is classified as C4S2 (high salinity with medium sodicity problem water). Chloride (Cl) and nitrate (NO3) concentrations were higher than the permissible limits according to World Health Organization Standards. The Ain Umm Sabah water is Na-Cl dominant water and can create soil sodicity problems and cause Na and Cl ion toxicity to plants if used for irrigation of sensitive crops. The spring water is under-saturated (negative SI) with respect to calcite, dolomite, gypsum, anhydrite, halite, fluorite and aragonite and oversaturated (positive SI) with respect to goethite, siderite and hematite minerals. The concentration of all the estimated trace metals was within the permissible limits for its use as drinking water and other purposes according to WHO. Since the spring water contains high concentration of NO3, hence can not be used for drinking purposes without prior treatment. The study findings suggest careful use and pumping of water from the spring. Further studies are required on regular basis to monitor the depletion in the spring water level and the temporal change in water salinity.