Pathogenicity of emerging Japanese type 1 porcine reproductive and respiratory syndrome virus in experimentally infected pigs

To clarify the pathogenicity of Japanese type 1 porcine reproductive and respiratory syndrome virus (PRRSV) isolate in experimentally infected pigs, we evaluated clinical signs and monitored viremia for 21 days post-inoculation (dpi). Lungs were mottled, tanned and reddish in appearance; had lesions predominantly in the cranial, middle and accessory lobes; and failed to collapse at 10 dpi. Although microscopic lesions of lungs were reproduced using the Japanese emerging type 1 PRRSV isolate under experimental conditions, no significant differences were noted between the challenge and control groups regarding mean rectal temperature and daily weight gain. These results provide useful insights into the limited pathogenicity of single infection with the Japanese type 1 PRRSV isolate in piglets, which differ from findings in reported field cases.     

‘Niigata S3’ is a new strawberry cultivar suitable for forcing culture under low temperature and insolation conditions

‘Niigata S3’ is a new strawberry (Fragaria × ananassa Duch.) cultivar that is early flowering and possesses high soluble solid content and good coloration. It was selected from a cross between Kei812 (seed parent) and ‘Asuka-Ruby’ (pollen parent). The first harvest date of ‘Niigata S3’ was December 27, 34 days earlier than ‘Echigohime’ and 9 days earlier than ‘Asuka-Ruby’ (means of 2007 and 2008). The marketable yield of ‘Niigata S3’ was 85% of ‘Echigohime’, 107% of ‘Asuka-Ruby’, while the early yield was 145% of ‘Echigohime’, 85% of ‘Asuka-Ruby’ (based on 2007 and 2008 means). The shape of the fruit is long conical, and its skin color medium-red. The fruit skin hardness of ‘Niigata S3’ was 31.5 g/mm², which was harder than ‘Echigohime’, and its average soluble solid content was 11.4%, which was higher than the values for ‘Echigohime’ and ‘Asuka-Ruby’ (2008). Furthermore, ‘Niigata S3’ did not bear apical overripe fruit. This new cultivar is adaptable to the climatic conditions of Niigata, as well as other regions that experience low winter temperatures and insolation.     

Protective immunity of sevenband grouper, Epinephelus septemfasciatus Thunberg, against experimental viral nervous necrosis

This paper describes the protective immune responses of sevenband grouper, Epinephelus septemfasciatus Thunberg, immunized with live piscine nodavirus, the causative agent of viral nervous necrosis (VNN), or the Escherichia coli – expressed recombinant coat protein. Nodavirus-neutralizing antibodies were detected at titres ranging from 1:158 to 1:1257 in serum of sevenband grouper which survived intramuscular injection with the virus, by a cell culture assay system. The virus-neutralizing ability of immune serum was also confirmed by injecting virus previously treated with serum into fish. This indicates establishment of acquired immunity in survivors and thus explains why survivors from natural infection are resistant to recurrence of the disease. Young sevenband grouper were immunized twice by intramuscular injections with the recombinant coat protein. Immunized fish produced neutralizing antibodies at high titres for at least 110 days and showed significantly lower mortalities in virus challenge tests. These results suggest the potential for vaccination against VNN in sevenband grouper, which is susceptible to piscine nodavirus at all life-stages.     

Expression of amphiregulin during the pre- and post-implantation period in the mouse reproductive tract

In mammals, embryo implantation is an essential step in reproduction. Implantation is a phenomenon that involves crosstalk between the blastocyst and the maternal endometrium. However, the molecular basis of the connections between the blastocyst and endometrium is not yet fully understood. Amphiregulin is a member of the epidermal growth factor family and is known to be expressed in the luminal epithelium of the mouse uterus on 3.5 days post coitum (dpc). Thus, to clarify the mechanism of amphiregulin at fetomaternal interface, we analyzed the expression pattern of amphiregulin mRNA in the oviducts and uteri of pregnant and psuedopregnant mice by means of real-time PCR. Amphiregulin expression in the pregnant uterus dramatically increased on 2.5 dpc, peaked on 3.5 dpc, and declined by 5.5 dpc. Furthermore, to analyze the effect of the presence of an embryo on amphiregulin expression, we determined the expression pattern of amphiregulin mRNA in the uterus after embryo transfer on 0.5 and 1.5 dpc. A previous study showed that the expression of amphiregulin mRNA depends on the concentration of progesterone. However, our present results indicate that amphiregulin mRNA is upregulated by the presence of fertilized eggs in the lumen of the oviduct on 0.5 dpc.