Sequential Clinical,Haematological, Biochemical,Immunopathological and Histopathological Alterations in Buffalo Calves (Bubalus bubalis) Intravenously Infected with Absidia corymbifera

Absidiosis was produced experimentally in 18 buffalo calves by intravenous inoculation of spores of Absidia corymbifera. Infected animals exhibited dullness, depression, partial anorexia and an initial pyrexia and coughing during the first week and two animals died on each of 9, 13 and 16 days post infection (DPI). The haemoglobin concentration and total erythrocyte count showed no appreciable change from their basal values at any stage of the experiment. However, the erythrocyte sedimentation rate and total leukocyte count increased significantly in the infected animals. The differential leukocyte count revealed a relative neutrophilia from 5 to 20 DPI. There was a significant increase in the serum total proteins, blood urea nitrogen, creatinine, alanine aminotransferase, aspartate aminotransferase, serum alkaline phosphatase, total immunoglobulins and circulating immune complexes in the infected animals as compared to the controls. In the sera of the infected animals, specific Absidia corymbifera IgM and IgG antibodies were detected from 3 DPI to 6 DPI respectively by Dot-EIA. Type I and type III skin hypersensitivity were detected from 10 DPI and type IV hypersensitivity from 15 DPI onwards. The gross and microscopic pathological lesions were seen mainly in the lungs, in all except one of the affected animals. This animal died 9 DPI and mycotic granulomas were also seen in its heart and kidneys. The microscopic lesions in the lung took the form of well-developed granulomas.     

Immunohistochemical staining of IFN-gamma positive cells in porcine reproductive and respiratory syndrome virus-infected lungs

Paraffin-embedded lungs were obtained from a previous porcine reproductive and respiratory syndrome virus (PRRSV)-challenged experiment involving three groups: an uninfected control group, a low virulence (LV, Resp PRRSV/Repro)-infected group, and a high virulence (HV, VR-2385)-infected group. Tissues were collected at 3, 7, 10, 14 or 28 days post-inoculation (DPI) (n=5). Lungs were examined to detect IFN-gamma positive cells by immunohistochemical staining using polyclonal antibodies to IFN-gamma. The microscopic lung lesions induced by the HV group were more severe than those in the LV group. A significant increase in number of lymphocytes in the HV group was observed at 10 DPI (24.90+/-9.79%), 14 DPI (22.00+/-11.47%) and 28 DPI (28.95+/-15.11%) (P<0.05). A relative decrease in macrophage numbers was observed and correlated well with the increase in lymphocyte numbers when the disease progressed. IFN-gamma positive cells were demonstrated in both lymphocytes and macrophages, particularly pulmonary alveolar macrophages. A significant increase in IFN-gamma positive cells was found at 7 DPI (15.90+/-13.65%), 10 DPI (46.95+/-13.79%), 14 DPI (10.90+/-5.13%) and 28 DPI (13.40+/-4.89%) in the HV group (P<0.05). The results suggested that the increase in IFN-gamma positive cells in the HV group correlated well with the severity of the lung lesions, which may be because of the presence of PRRSV in the lung.     

Variation of the CD4, CD8, and MHC II cell population in granulomas of immunocompetent and immunosuppressed rabbits in Encephalitozoon cuniculi infection

Encephalitozoon cuniculi (E. cuniculi) is a fungi-related, obligate, zoonotic, spore-forming intracellular eukaryotic microorganism. This emerging pathogen causes granulomas in brain and kidneys of infected individuals. The objective of this study was to detect the distribution of CD4, CD8 and MHCII-positive cells within granulomas in these organs in infected immunocompetent (group A) and infected immunosuppressed (group B) New Zealand white rabbits using immunohistochemistry. In brain, labeled CD4 immune cells were mainly located in the periphery of granulomas in group B. Kidneys of groups A and B, displayed CD4-positive in granulomas and were significant different when compared to brain. CD8 immune cells in brain and kidneys were disseminated in the granulomas in groups A and B; however, no significant difference was observed. MHCII-positive cells were more numerous in brain sections of group B and were significantly different when compared to kidney sections. Granulomas were not observed in control animals of group C and D. In conclusion, we identified CD4-positive cells in both the brain and kidneys of immunocompetent and immunosuppressed animals; CD8-positive cells were more numerous in brain of immunosuppressed rabbits and MHCII cells were more predominant in brain of immunocompetent rabbits. Apparently, the immunosuppression stimulated a change in the cellular phenotype of Th1- to Th2-like granulomas in brain and kidneys by an unknown mechanism. These results increase our understanding of CD4, CD8 and MHCII positive cells within the E. cuniculi granuloma microenvironment and will help in future microsporidian granulomas studies of both immunocompetent and immunosuppressed individuals.     

Pathogenicity of an avian influenza virus serotype H9N2 in chickens

A low pathogenic avian influenza virus (AIV) serotype H9N2 affected many commercial flocks in the Middle East in late 1990s and early 2000s. Due to the varying pathogenicity ofAIV H9N2 reported in previous studies, this study was carried out to determine the pathogenicity of a Jordanian isolate of H9N2 in broiler and specific-pathogen-free (SPF) chickens. Mild tracheal rales were observed in the broilers but not in the SPF birds starting 3 days postinfection (DPI) and until the end of the experiment at 16 DPI. Infected chickens had gross and histologic changes limited to the respiratory system (sinuses, trachea, lungs, and air sacs) characterized by congestion and lymphoplasmacytic inflammation. However, the lesions in the broiler chickens were more severe than those in the SPF chicks. Furthermore, the virus caused significant (P = 0.004) reduction (230 g) in average body weight of the infected broiler group compared with the uninfected broiler group. Both broiler and SPF-infected groups seroconverted, and they had a geometric mean titer of 2(8.2) and 2(9.3), respectively, on the hemagglutination inhibition test at 16 DPI. Cloacal virus shedding was not detected by 9 DPI and 15 DPI in broiler and SPF-infected groups, respectively. This study demonstrated the pathogenic nature of the local Jordanian H9N2 isolate and the variation from what it has been reported in other countries of the region. Regional effort should be directed to start an eradication program of this disease because of its pathogenicity for chickens, wide distribution, and possible interference with surveillance for H5N1 serotype.     

猪源脑心肌炎病毒GXLC株对小鼠的致病性试验

为研究猪源脑心肌炎病毒(EMCV)GXLC株对小鼠的致病性,将其接种4周龄健康BALB/c小鼠,观察临床症状,检查病理变化,测定心重/体重比值,检测心脏、脑、脾脏组织及血清中病毒含量,检测心脏、脑、脾脏组织中细胞因子IL-1β、TNF-α、IL-6 mRNA表达水平及血清中IL-1β、TNF-α蛋白含量。结果显示,感染小鼠出现明显的临床症状,感染后第4天开始死亡,第5~7天死亡达到高峰;心脏、脑出现典型的大体病理变化和组织病理学变化,心重/体重比值显著升高、组织病理学炎症分值显著增加;感染后第1天即可在心脏、脑、脾脏及血清中检测到大量病毒,直至第14天仍能检测到病毒;血清中IL-1β、TNF-α蛋白含量显著升高,心脏、脑、脾脏组织中IL-1β、TNF-α、IL-6 mRNA表达水平显著上调,而且细胞因子表达的高峰期与出现明显临床症状、严重病理损害及死亡高峰期密切相关。结果表明,猪源EMCV GXLC株对小鼠具有高度致病性,IL-1β、TNF-α、IL-6等促炎细胞因子在EMCV对小鼠的致病机制中发挥重要作用。     

Experimental dual infection of specific pathogen-free pigs with porcine reproductive and respiratory syndrome virus and pseudorabies virus

Twenty 6-week-old specific pathogen-free pigs were divided into four groups. On day 0 of the experiment, PRRSV-PRV (n = 6) and PRRSV (n = 4) groups were intranasally inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) (10(5.6) TCID50). On day 7, the PRRSV-PRV and PRV (n = 6) groups were intranasally inoculated with pseudorabies virus (PRV) (10(3.6) TCID50). Control pigs (n = 4) were kept as uninoculated negative controls. Half of the pigs in each group were euthanized and necropsied on day 14 or 21. Clinical signs such as depression and anorexia were observed in the PRRSV-PRV and PRV groups after inoculation with PRV. Although febrile response was observed after virus inoculations, the duration of that response was prolonged in the PRRSV-PRV group compared with the other groups. The lungs in the PRRSV-PRV group failed to collapse and were mottled or diffusely tan and red, whereas the lungs of the pigs in the other groups were grossly normal. Histopathologically, interstitial pneumonia was present in all PRRSV-inoculated pigs, but the pneumonic lesions were more severe in the PRRSV-PRV group. Mean PRRSV titres of tonsil and lung in the PRRSV-PRV group were significantly (P < 0.05) higher than that in the PRRSV group on day 21. These results indicate that dual infection with PRRSV and PRV increased clinical signs and pneumonic lesions in pigs infected with both viruses, as compared to pigs infected with PRRSV or PRV only, at least in the present experimental conditions.     

Diagnosis and manifestation of encephalitozoonosis in mice after experimental infection with different species and application of dexamethasone

Twenty-eight BALB/c mice were infected with different strains of Encephalitozoon species (Encephalitozoon cuniculi II - mouse type, E. cuniculi III - dog type, Encephalitozoon hellem, Encephalitozoon intestinalis). Five of them were infected with E. cuniculi II (mouse type) and simultaneously immunosuppressed with dexamethasone. Clinical signs of encephalitozoonosis were not remarkable. Ascites was found in two mice of dexamethasone-treated group 14 days post-infection (p.i.). The histopathological changes were found mainly in spleen and liver in the form of lymphoepithelioid granuloma. Spores were found in faeces since day 14 p.i. and visualized by Calcoflour White M2R. After cultivation on cellular cultures (VERO E6 - monkey kidney cells, RK-13 - rabbit kidney fibroblasts), the species differentiation was performed by PCR using panmicrosporidial primers (PMP1, PMP2) and specific primers (ECUN-F, ECUN-R, V1, SI-500). The differences were recorded in the immune response of immunocompetent and immunosuppressed mice. At day 60 p.i., the titres of specific antibodies measured by indirect immunofluorescence antibody test were lower (1:4096) in dexamethasone-treated mice when compared with non-immunosuppressed animals (1:8196). The significant increases of antibody titres were recorded in particular infected groups within the experiment (P < 0.01 between day 14 p.i. and day 30 p.i., P < 0.001 between day 14 p.i. and day 60 p.i.). Experimental encephalitozoonosis in non-immunosuppressed and immunosuppressed mice provides a useful model for the study of immune response and lesions associated with these protozoans.     

Pathogenesis of porcine reproductive and respiratory syndrome virus-induced increase in susceptibility to Streptococcus suis infection

Eighty 3-week-old crossbred pigs were randomly assigned to six groups (13-14 pigs/group). Group 1 pigs served as uninoculated controls, group 2 pigs were inoculated intranasally (i.n.) with Streptococcus suis serotype 2, group 3 pigs were inoculated i.n. with a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine, group 4 pigs were inoculated i.n. with the same vaccine and with S. suis, group 5 pigs were inoculated i.n. with VR-2385 (a high-virulence strain of PRRSV), and group 6 pigs were inoculated i.n. with VR-2385 and S. suis. Pigs exposed to both PRRSV and S. suis were inoculated with PRRSV 7 days prior to S. suis inoculation. The pigs were 26 days old when inoculated with S. suis. Respiratory disease was significantly more severe in groups 5 and 6. Mortality rate was the highest in group 6 (87.5%). This rate was significantly higher than that observed in all other groups except group 4 (37.5%). The mortality rate in group 2, inoculated with S. suis alone, was 14.3%. No pigs from groups 1, 3, or 5 died prior to the scheduled necropsies at 10 and 28 days postinoculation with PRRSV (DPI). To study the effect of PRRSV and/or S. suis on pulmonary clearance by pulmonary intravascular macrophages, six pigs from each group were intravenously infused with 3% copper phthalocyanine tetrasulfonic acid in saline prior to necropsy at 10 DPI. Mean copper levels in the lungs of pigs in groups 2, 5, and 6 were significantly lower than those in control pigs. The mean percentage of lung tissue grossly affected by pneumonia at 10 DPI was 0%, 1%, 0%, 3%, 64%, and 62% for groups 1-6, respectively. Both gross and microscopic interstitial pneumonia lesions were significantly more severe in the VR2385-inoculated groups (5 and 6). PRRSV was isolated from bronchoalveolar lavage fluid collected at necropsy from 100% of the pigs in groups 5 and 6, 71.4% of pigs in group 4, 38.5% of pigs in group 3, and none of the pigs in groups 1 or 2. Streptococcus suis serotype 2 was cultured from the internal tissues of 7.7%, 28.6%, and 78.6% of the pigs in groups 2, 4, and 6, respectively. Streptococcus suis serotype 2 was isolated from whole blood at necropsy from 7.7%, 35.7%, and 78.6% of pigs in groups 2, 4, and 6, respectively. Significantly more pigs in group 6 had S. suis isolated from whole blood and internal tissues. In summary, both high-virulence PRRSV and S. suis decreased copper clearance, and the incidence of isolation of S. suis and PRRSV was higher in dually inoculated pigs. PRRSV-induced suppression of pulmonary intravascular macrophage function may in part explain PRRSV-associated increased susceptibility to S. suis infection.     

Acute phase response in mice experimentally infected with Trypanosoma congolense: a molecular gauge of parasite-host interaction

Mice infected with Trypanosoma congolense developed a severe anaemia 1 week after infection, which persisted till treatment with diminazine aceturate when the packed cell volume (PCV) recovered to pre-infection levels. This was accompanied by a marked increase in the plasma levels of the acute phase proteins (APP), serum amyloid P-component (SAP) and haptoglobin (Hp). The initial peak levels of Hp and SAP were attained 7 and 12 days post-infection (DPI), respectively. Thereafter SAP levels decreased significantly to near pre-infection levels, but later increased even after treatment to give a second peak 34 DPI after which there was a decline till the study was terminated. The Hp levels on the other hand decreased to an intermediate level after the initial peak increasing to a second peak 22 DPI. Thereafter Hp decreased significantly following diminazine aceturate treatment to reach pre-infection levels within 5 days post-treatment. This indicates that T. congolense-infected mice develop severe anaemia accompanied by an acute phase response leading to an increase in SAP and Hp but that following treatment divergent responses occurred indicating differences in the pathways for stimulation of the APP. Haptoglobin was shown to be an earlier indicator of infection and a better marker in monitoring the response to treatment.     

Progressive changes in serum proteins and the rheumatoid factor of chickens infected with Mycoplasma synoviae.

Sera from controls and chickens infected with Mycoplasma synoviae were examined for serum protein content by cellulose-acetate electrophoresis, and for rheumatoid factor (RF) by a latex-agglutination test at 8, 18, 28, 38, and 48 days postinoculation (DPI). Mean total serum protein concentration was significantly elevated by 8 DPI and rose to much higher concentrations on each subsequent day of examination. The mean albumin concentration was significantly decreased by 8 DPI, and continued to decline to very low levels at 18 and 28 DPI, after which it began to rise and by 48 DPI did not significantly differ from the controls. The mean alpha-globulin concentrations were significantly elevated on all days of examination. The mean beta- and gamma-globulin concentrations were significantly elevated by 8 DPI and reached maximum levels at 18 DPI but remained elevated throughout the test. The percentage of chickens having RF titers increased on each successive examination day, but only 56% of the chickens had titers at 48 DPI.     

Ultrastructural Observation of Nasal and Pulmonary Intracellular Pasteurella multocida A:3 in Rabbits

Sixteen 8- to 9-week-old Pasteurella multocida-free rabbits were divided into two equal groups. Eight rabbits in one group were inoculated intranasally with P. multocida type A:3. The other eight were inoculated intranasally with phosphate-buffered saline and used as controls. Nasal swabs taken before and after inoculation were cultured for bacterial isolation. Post-mortem nasal swabs and lung samples were cultured for bacteriological isolation. Nasal mucosa and lung samples were collected and processed for transmission electron microscopy. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits and from the lungs of four infected rabbits. Degenerative ultrastructural changes in epithelial cells and endothelial cells were seen in the infected rabbits. Deciliation of the cilated epithelium and hyperplasia of the goblet cells in the nasal mucosa were noted. Thickening of the alveolar septa due to hyperplasia of type II pneumocytes, swelling of the endothelial lining of capillaries and infiltration of inflammatory cells were also observed. Intracellular invasion of the nasal epithelial cells and of type II pneumocytes by the organism was observed. Coccobacilli were observed in membrane-bound vacuoles in the cytoplasm of these cells. The vacuoles were adjacent to the host-cell mitochondria and some of these vacuoles appeared to be fused to the mitochondrial membrane. Some type I pneumocytes with intracellular membrane-bound vacuoles containing bacterial cells showed protrusions, which appeared to detach into the alveolar lumina. These results indicated that P. multocida serotype A:3 in rabbits can invade the epithelial cell and cause structural changes in the interstitium, epithelium and endothelium. Heterophils and macrophages appear to play important roles in tissue injury.     

Histopathology and physiopathology of gastric mucous hyperplasia in rats heavily infected with Taenia taeniaeformis.

Rats heavily infected with larval Taenia taeniaeformis show hyperplasia of the gastric mucosa accompanied by mucous cell proliferation, increase in the level of intragastric pH and hypergastrinemia. Sixty one rats were divided into 2 groups designed as infected (36 rats) and control (25 rats) group. These rats were examined with time course of the infection histopathologically and physiopathologically, during 14-112 days postinfection (DPI). In the infected rats, gastric mucosal hyperplasia began to be observed at 56 DPI, and the structural disturbance of zymogenic units in the corpus and mucous units in the antrum had increased with time. However, the degree of these changes in the antrum was weaker than those in the corpus. Alcianblue and/or PAS-positive cells increased in their numbers with time, and 4 types of cells other than typical surface mucous cell and mucous neck cell were observed by electron-microscopy. However, zymogenic and parietal cells decreased in their number after 56 DPI. Further, the infected rats showed changes in the serum concentration of alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, glucose and total protein. Some similarities with Menetrier's disease were discussed.     

Interactions of highly and low virulent Mycoplasma hyopneumoniae isolates with the respiratory tract of pigs

Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia, a chronic nonfatal disease affecting pigs of all ages. To obtain better insight in the mechanisms responsible for differences in virulence between highly and low virulent M. hyopneumoniae isolates, 23 caesarean-derived, colostrum-deprived piglets were randomly assigned to three groups. Groups 1 and 2 consisted of nine animals each, which were intratracheally inoculated at 1 week of age with a highly or a low virulent isolate of M. hyopneumoniae, respectively. The remaining five animals were inoculated with sterile culture medium. Animals were euthanized at 5, 10, 15 and 28 days post-inoculation (DPI). Animals inoculated with the highly virulent isolate had more neutrophils in BAL fluid at 10, 15 and 28DPI compared to the other groups. At 10 and 15DPI, animals in the highly virulent group had significantly higher concentrations of TNF-alpha in BAL fluid. IL-1beta concentration in this group was higher at 5 and 28DPI compared to the other groups. From 10DPI onwards, significantly higher titres of M. hyopneumoniae were detected in the BAL fluid of animals inoculated with the highly virulent isolate compared to animals inoculated with the low virulent isolate. Additionally, the in vitro generation time of the highly virulent M. hyopneumoniae isolate was significantly shorter than that of the low virulent isolate. The present study indicates that the difference in pathogenicity between the highly and low virulent isolates is associated with a faster in vitro growth, a higher capacity to multiply in the lungs and the induction of a more severe inflammation process by the highly virulent isolate.     

栀子四黄散抗猪繁殖与呼吸综合征的研究

为探索栀子四黄散对猪繁殖与呼吸综合征（porcine reproductive and respiratory syndrome,PRRS）的治疗效果,本研究将45头组随机分为对照组、病毒组及中药高、中、低剂量组5组,每味中药400目超微粉碎后分别添加饲喂接种猪繁殖与呼吸综合征病毒（porcine reproductive and respiratory syndrome virus,PRRSV）的试验猪,连续饲喂14 d,每日观察临床症状,7、14和21 d时随机采集5组血清样品进行细胞因子检测,并进行病理剖检和采集肺脏样品进行病理组织切片观察。结果显示,添加中药7 d后临床症状均减轻,中剂量和高剂量组第14天时体温恢复正常,呼吸困难症状消失,食欲恢复,中药治疗组肺脏未见肉样变,肺脏表面有出血点或出血斑。中剂量组肺泡间隔增厚,轻度淤血,肺实质轻度炎性细胞浸润。病毒组猪血清中IgG和γ-干扰素（IFN-γ）含量逐渐降低,白介素-10（IL-10）含量逐渐上升。添加中药的3组血清中IgG含量均高于病毒组,并且IgG含量均随时间延长逐渐上升,中剂量组血清中IgG含量均极显著高于对照组和病毒组（P<0.01）;添加中药的3组IFN-γ含量逐渐上升,14和21 d时中剂量组血清中IFN-γ含量均极显著高于对照组和病毒组（P<0.01）;中剂量组血清中IL-10含量逐渐降低,14和21 d时与病毒组差异极显著（P<0.01）,与对照组差异不显著（P>0.05）。综上,栀子四黄散可有效改善试验猪临床症状、病理变化和细胞因子的分泌,中剂量组效果最好。本研究为中药防治PRRS提供了试验依据。     

The acute phase response in calves experimentally infected with bovine viral diarrhoea virus and/or Mannheimia haemolytica

The aim of this investigation was to study differences and similarities in the acute phase response of calves experimentally infected in the respiratory tract with either bovine viral diarrhoea virus (BVDV) or Mannheima haemolytica (Mh), or with a combination of both (BVDV/Mh). A non-inoculated control group was also included. The acute phase response was measured by serum or plasma concentrations of the acute phase proteins (APPs) haptoglobin, serum amyloid A (SAA) and fibrinogen, and of cortisol, prostaglandin F2alpha-metabolite and interferon-alpha (IFN-alpha) activity. Clinical symptoms were also recorded and were most severe in the BVDV/Mh group. The symptoms were mild to moderate in the BVDV group, while none, or very mild symptoms were observed in the Mh group. In all inoculated groups, a significant acute phase response was observed, with elevated values of haptoglobin, SAA and fibrinogen, while the control group remained unaffected throughout the study. In general, the magnitude of the response was similar, but the duration of elevated concentrations of APPs was significantly longer in the BVDV/Mh group than in the BVDV group, reflecting the duration of the clinical symptoms. However, in the single infection groups, the APP response and the clinical symptoms were not correlated. The IFN-alpha activity increased in all BVDV-inoculated animals, but no response in cortisol and PGF2alpha-metabolite concentrations was observed after infection. Basal levels of serum concentrations of haptoglobin, SAA and fibrinogen were established and may be used for evaluating calf health in herds. The duration of elevated haptoglobin, SAA and fibrinogen values did not differ significantly within groups indicating that their value as indicator of disease is equal.     

Experimental study of pathogenicity of Pasteurella multocida serogroup F in rabbits

The role of Pasteurella multocida serogroup F in inducing disease in rabbits was investigated in this study. Three groups of 12 Pasteurella-free rabbits each were intranasally (i.n.), subcutaneously (s.c.), and perorally (p.o.) challenged, respectively. Six rabbits of each group were immunosuppressed using dexamethasone. Eight rabbits (four of them immunosuppressed) inoculated i.n. showed symptoms of respiratory distress resulting in respiratory failure and died or were euthanized in the terminal stage of the disease 3-6 days post-infection (p.i.). The main pathological findings were fibrinopurulent pleuropneumonia (immunocompetent rabbits) or diffuse haemorrhagic pneumonia (immunosuppressed rabbits). Septicemic syndrome ending with shock occurred in 11 rabbits (6 of them immunosuppressed) inoculated s.c., which died or were euthanized in the terminal stage of the disease 2-3 days p.i. The most significant pathological findings were extensive cutaneous and subcutaneous lesions. All of the p.o. inoculated rabbits survived the challenge showing no clinical signs of the disease and no macroscopic lesions. The observations in this study indicate that in addition to serogroups A and D of P. multocida, serogroup F also can be highly pathogenic for rabbits and therefore might be a cause of considerable economic loss in commercial rabbit production.     

Porcine circovirus type 2 (PCV2) distribution and replication in tissues and immune cells in early infected pigs

Replication of porcine circovirus type 2 (PCV2) in pigs, as measured by spliced capsid mRNA (Cap mRNA) and viral DNA, was investigated following experimental infection. Peripheral blood mononuclear cells (PBMCs), and tissue from bronchial lymph nodes (BLN), inguinal lymph nodes (ILN), tonsils, lungs, liver, kidneys, spleen and thymus from infected pigs on different days post-infection (DPI) were assessed. PCV2 replication differed dramatically between tissues from the same infected pig. The virus actively replicated in most tested tissues at 14DPI in association with increased PCV2 associated lesions and PCV2 antigen levels, although no clinical signs correlated with PCV2 associated disease were observed in infected pigs during the course of the study. The PCV2 Cap mRNA was detected only at 13DPI in PBMCs from infected pigs, suggesting replication of the virus in circulating blood is transient and not a major site for PCV2 replication in vivo. Evaluation of the Cap mRNA and viral DNA synthesis in T and B lymphocyte and monocyte populations from PBMCs and BLN at various intervals post-inoculation revealed replication of PCV2 in all cell subpopulations; however, viral replication in B lymphocytes was greater than observed in mononuclear cells isolated from BLN at 14DPI indicating that B lymphocytes may be an important cell population for PCV2 replication. These findings further our understanding of the cell types permissive for PCV2 replication and the pathogenesis of PCV2 infection in vivo.     

Antiviral effect of dietary germanium biotite supplementation in pigs experimentally infected with porcine reproductive and respiratory syndrome virus

Germanium biotite (GB) is an aluminosilicate mineral containing 36 ppm germanium. The present study was conducted to better understand the effects of GB on immune responses in a mouse model, and to demonstrate the clearance effects of this mineral against Porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected pigs as an initial step towards the development of a feed supplement that would promote immune activity and help prevent diseases. In the mouse model, dietary supplementation with GB enhanced concanavalin A (ConA)-induced lymphocyte proliferation and increased the percentage of CD3+CD8+ T lymphocytes. In pigs experimentally infected with PRRSV, viral titers in lungs and lymphoid tissues from the GB-fed group were significantly decreased compared to those of the control group 12 days post-infection. Corresponding histopathological analyses demonstrated that GB-fed pigs displayed less severe pathological changes associated with PRRSV infection compared to the control group, indicating that GB promotes PRRSV clearance. These antiviral effects in pigs may be related to the ability of GB to increase CD3+CD8+ T lymphocyte production observed in the mice. Hence, this mineral may be an effective feed supplement for increasing immune activity and preventing disease.