Safety of a live attenuated Erysipelothrix rhusiopathiae vaccine for swine

The porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus. Virions of PRRSV contain six membrane proteins: the major proteins GP5 and M and the minor proteins GP2, GP3, GP4, and E. The GP5 is the major envelope proteins, which was involved in the formation and infectivity of PRRSV by coaction with other membrane proteins. Here, to determine the function of alone GP5 envelope protein in viral entry, we investigated the formation and infectivity of GP5-pseudotyped virus particles. By co-transfection of GP5 expression plasmids with murine leukemia virus (MuLV) based retroviral vectors (pHIT60, encoding MuLV Gag-Pol; pHIT111, encoding an MuLV genome with a β-galactosidase reporter gene) into 293 T cells and analysis of the culture medium using ultracentrifugation, Western blot, and infection assay. We observed that the GP5 envelope protein was incorporated into the MuLV retroviral vectors to generate an pseudotyped murine leukemia virus, which was infectious to PAM and Mack-145 target cells and displayed the same host range with wild-type PRRSV. The infection of the pseudotyped virus on PAM target cells is effectively neutralized by polyclonal antibodies specific for PRRSV or GP5. The results suggested that the GP5 protein may play a key role in the viral entry by interacting with the host cell receptor. The GP5-pseudotyped virus will be useful in the identification of the cellular receptor binding with GP5 protein.     

Disease outcome and cytokine responses in cats immunized with an avirulent feline infectious peritonitis virus (FIPV)-UCD1 and challenge-exposed with virulent FIPV-UCD8

Eight cats were immunized with an avirulent strain of feline infectious peritonitis virus (FIPV)-UCD1, then challenge-exposed to a highly virulent cat passaged strain (FIPV-UCD8). Th1 and Th2 cytokine profiles in the peripheral blood mononuclear cells (PBMCs) were measured throughout in the experiment. No clinical signs of FIP were evident in the experimental cats after immunization. After challenge, the immunized cats demonstrated one of four clinical outcomes: (1) classical effusive FIP; (2) accelerated FIP; (3) non-effusive FIP, or (4) resistance to challenge. Only minor cytokine changes were observed following immunization, however, several cytokine changes occurred following challenge-exposure. The most noteworthy changes were in tumor necrosis factor-alpha (TNF-alpha) and interferon gamma (IFN-gamma) levels. Our preliminary findings suggest that immunity against FIP is associated with TNF-alpha and IFN-gamma response imbalance, with high TNF-alpha/low IFN-gamma mRNA responses favouring disease and low TNF-alpha/high IFN-gamma mRNA responses being indicative of immunity.     

Involvement of cytolytic and non-cytolytic T cells in the control of feline immunodeficiency virus infection

The appearance of non-cytolytic T cells that suppressed feline immunodeficiency virus (FIV) replication in vitro, and FIV-specific cytotoxic T cell (CTL) responses was compared in a group of seven, specific pathogen free (SPF) domestic cats following primary infection with the Glasgow(8) isolate of FIV (FIV(GL-8)). FIV proviral burdens were quantified in the blood and lymphoid tissues by real-time PCR. Non-cytolytic T cell suppression of FIV replication was measured by co-cultivating lymphoblasts prepared from the cats at different time-points during infection with FIV-infected MYA-1 cells in vitro. Non-cytolytic suppressor activity was detected as early as 1 week after infection, and was evident in all the lymphoid tissues examined. Further, this activity was present in subpopulations of T cells in the blood with normal (CD8(hi)) or reduced (CD8(lo)) expression of the CD8 molecule, and temporal modulations in non-cytolytic suppressor activity were unrelated to the circulating CD8(+) T cell numbers. Virus-specific CTL responses, measured by (51)Cr release assays, were not detected until 4 weeks after infection, with the emergence of FIV-specific effector CTLs in the blood. Throughout infection the response was predominantly directed towards FIV Gag-expressing target cells, and by 47 weeks after infection CTL responses had become localised in the lymph nodes and spleen. The results suggest that both non-cytolytic T cell suppression of FIV replication and FIV-specific CTL responses are important cellular immune mechanisms in the control of FIV replication in infected asymptomatic cats.     

Genetic variability of Chlamydophila abortus strains assessed by PCR-RFLP analysis of polymorphic membrane protein-encoding genes

Torque teno viruses (TTVs) are vertebrate infecting, small viruses with circular single stranded DNA, classified in the Anelloviridae family. In pigs, two different TTV species have been described so far, Torque teno sus virus 1 (TTSuV1) and 2 (TTSuV2). TTSuVs have lately been linked to postweaning multisystemic wasting syndrome (PMWS). In the present study, TTSuV1 and TTSuV2 prevalence and DNA loads in longitudinally collected serum samples of healthy and PMWS affected pigs from Spanish conventional, multi-site farms were analyzed. Serum samples were taken at 1, 3, 7, 11 and around 15 weeks of age (age of PMWS outbreak) and viral DNA loads determined by quantitative PCR. For both TTSuV species, percentage of viremic pigs increased progressively over time, with the highest prevalence in animals of about 15 weeks of age. TTSuV1 and TTSuV2 viral DNA loads in healthy and TTSuV1 loads in PMWS affected animals increased until 11 weeks of age declining afterwards. On the contrary, TTSuV2 DNA loads in PMWS affected pigs increased throughout the sampling period. It seems that TTSuV species differ in the in vivo infection dynamics in PMWS affected animals.     

Evaluation of promoters and visual markers for transformation of eastern white pine

This report serves to evaluate possible promoters for use in theproduction of transgenic eastern white pine (Pinus strobus L.).Embryogenic cultures of eastern white pine were bombarded with goldparticles coated separately with a variety of gene constructs containingthe UidA -glucuronidase (GUS) or green fluorescentprotein (GFP) reporter gene. Transient expression of the UidAgene, driven by a novel algal virus adenine methyl transferase genepromoter, as well as five other promoters used in angiospermtransformation, were evaluated. The maize alcohol dehydrogenase promoterwas not effective in eastern white pine cultures. The construct with thedoubled Cauliflower Mosaic Virus 35S promoter plus Alfalfa Mosaic Virusenhancer showed the highest levels of expression. GUS expression wasdetected within 24 hours, but decreased after 5 days and was notdetectable 15 days after bombardment. Expression of GUS activity wasrecorded mainly in somatic embryonal heads of various stages ofdevelopment and occasionally in suspensor cells. Similar to GUSexpression, modified green fluorescent protein (GFP) was detected in theembryonal head cells 24 hours after bombardment. GFP-expressingsuspensor cells were both more infrequent and difficult to detect, astheir highly vacuolate nature rendered the GFP presence less visibleagainst the yellow background autofluorescence.