Molecular characterization and pathology of field isolates of foot-and-mouth virus in Swiss albino mice

Abstract Foot-and-mouth disease is responsible for severe economic losses to the livestock industry of Pakistan. This study aimed to use Swiss albino mice as a cost-effective experimental animal model to study different immunological and histopathological aspects of FMDV instead of natural targeted species like cattle. After isolation of field isolates FMDV on BHK-21 cell line, biological titer of the virus and mice infectious dose50 was calculated. Virus was injected in 45 Swiss albino mice (group A) through intraperitoneal route. The gross, histopathological and immunopathological lesions in heart, trachea and lungs were recorded at different day’s intervals. Histopathologically, the heart showed congestion, hemorrhages and necrosis of cardiac muscles. Trachea showed deciliated epithelium and lungs showed hemorrhages, bronchial edema and alveolar emphysema. Immunohistochemical studies revealed the presence of virus in cardiac muscles, tracheal and bronchial epithelium and alveolar lumen. The findings evoked a thought that laboratory animals could be an alternative to large animals to meet budget limitations for further research on foot-and-mouth-disease.

Elucidating antiviral activity of Curcuma longa against H9 N2 influenza virus using embryonated chicken egg model

Curcumin is a potent antimicrobial herb used traditionally as a spice in culinary. This study was designed to evaluate the antiviral effects of curcuma longa extract against H₉ influenza virus. A total of 60 embryonated eggs were equally divided into 5 groups with 12 eggs in each group. Group 1 (G1) served as uninfected negative control. Whereas Group 2 (G2) was kept as positive control infected with known virus @ 0.2 ml with 10^-9.3 EID₅₀. Group 3 (G3) was offered Curcuma longa @ 0.2 mg/0.2 ml and H₉N₂ virus (@ 0.2 ml with 10^-9.3 EID₅₀. Similarly, Group 4 (G4) was inoculated with extract of Curcuma longa @ 0.2 mg/0.2 ml per egg, whereas Group 5 (G5) was given Ribazole @ 0.2 ml/ egg. The crude extract and virus were administered on the 15^th day of incubation and were checked after every 24 hours up to 96th hour post inoculation by random selection of 3 eggs. Death and survival rate were noted in all groups. Gross and histopathological lesions were also observed. Results revealed that Curcuma longa extract had significantly (p<0.05) reduced the mortality rate of embryos infected with H₉N₂ virus. In G3, increased lymphocytes and mild fatty changes were seen in liver. Whereas, mature RBCs, plasma cells and some lymphoblast's were observed in Spleen. Similarly, the bursa follicles were with lymphocytic aggregation. The G4 (Curcuma longa) and G5 (Ribazole) were with maximum embryo survival after 48 and 72 h post inoculation. This study revealed potential antiviral activity of Curcuma longa against H9N2 influenza viruses and can be opted as alternative to antibiotics and antiviral drugs to minimize the antimicrobial resistance in human and animal population.

Pathogenesis and tissue tropism of Newcastle disease virus and avian influenza virus (H9N2) in single and mixed infections

Newcastle disease (ND) and avian influenza (AI) are globally considered as a serious threat to the chicken and other avian species. The paramyxovirus type 1 and orthomyxovirus type A are RNA viruses, which cause ND and AI infection, respectively.

Efficacy of commercial vaccines against the prevalent strains of Newcastle disease and avian influenza (h9n2) infections in broilers in Pakistan

TThe efficacy of the two commonly used commercial vaccines for Newcastle disease (ND) and low path avian influenza (LPAI) H9N2 were evaluated against field virus in broiler chicks. One hundred one-dayold commercial broiler chicks were divided into four groups (A to D) with an equal number of birds per group. Group A and B were vaccinated against H9N2 and NDV, respectively, at day 7 of age while group C served as positive infected control for H9N2 and group D for NDV. Serum samples from birds in all groups were tested for presence of antibodies against H9N2 and NDV at day 21 of age. Subsequently, on day 28 of age, groups A and C were challenged with the field strain of H9N2 virus, and Group B and D with NDV. Birds were monitored for a period of 2 weeks for development of any clinical signs and mortality. The geometric mean titer were high in groups A (4.90) and B (7.3), and low in the unvaccinated groups C (0.7) and D (1.1). The highest and lowest value of H9N2 antibody titer detected through ELISA were 1.498 and 0.502, respectively. The S/P ratios greater than 0.5 were considered positive. The highest and lowest value for NDV antibody titer detected through ELISA were 783 and 882, respectively. Serum samples with titer greater than 396 were considered positive and indicated vaccination or other exposure to NDV. On histological examination severe congestion, necrosis, degeneration, hemorrhages and leukocyte infiltration were observed in intestine, lungs, trachea and bursa of Fabricius of the non-vaccinated group post-infection. Mild tissues changes were observed in the vaccinated group. It can be concluded from the findings that the commonly used commercial vaccines may provide effective protection against the circulating H9N2 and ND virus in broiler birds by producing protective antibody titer.