Conference Presentation

2015

１．

Effect of inactivated type 2 porcine reproductive and respiratory syndrome virus possessing a small number of n-linked glycosylation sites in glycoprotein 5 as a vaccine against homologous and heterologous strains.

Sato, T.¹⁾, Taira, O.¹⁾, Nagao, A.¹⁾, Oroku, K.¹⁾, and Tsutsumi, N.¹⁾
¹⁾ Nippon Institute for Biological Science
International Symposium on Emerging and Re-emerging Pig Diseases (ISERPD2015), Kyoto Japan
Abstract： The modified-live virus (MLV) and killed virus (KV) vaccines are commercially available for the control of porcine reproductive and respiratory syndrome (PRRS) in the worldwide. The PRRS KV vaccine is much safer than MLV vaccine in respect of a risk for reversion to virulence in the field use; however, in general, it is thought to be less immunogenic than the MLV vaccine. We isolated Gu922M strain of type 2 PRRS virus from a pig affected with postweaning multisystemic wasting syndrome in Japan. In contrast to the majority of PRRSV strains having four N-linked glycosylation sites in the viral glycoprotein 5 (GP5) containing a major neutralizing epitope, Gu922M possesses only two glycosylation sites in the GP5. The presence of glycans around the neutralizing epitope has been suggested to interfere with the neutralizing antibody response against PRRS virus. In this study, we attempted to develop a KV vaccine using Gu922M and evaluated the efficacy of this vaccine candidate homologous and heterologous PRRS virus challenges.

２．

Oral delivery of enteric-coated TGE vaccine protects piglets from TGE by passive transfer of maternal antibodies

Takeyama, N.¹⁾, Sato, T.¹⁾, Hosokawa, T.¹⁾, Sato, I.¹⁾, Sugiyama, M.²⁾, and Kusanagi, K.¹⁾
¹⁾ Nippon Institute for Biological Science
²⁾ Freund Corporation
Asian Pig Veterinary Society Congress 2015, Manila
Abstract: 【Introduction】 Transmissible gastroenteritis virus (TGEV) invades intestinal epitherial cells and causes severe diarrhea in neonatal piglets. A passive transfer of TGEV-specific maternal antibodies to intestinal tracts of neonates is the major protective measure against TGEV infection. In this study, we orally administrated TGE vaccine encapsulated in enteric capsules to pregnant sows and evaluated the vaccine efficacy to protect their neonates against TGE. 【Materials and methods】 The enteric capsules consisted of three layers; a hydrophilic core containing live attenuated H5 strain of TGEV, lipophilic intermediate layer, and enteric outer shell to maintain its particle structure. To evaluate vaccine efficacy of the TGEV-capsules, two pregnant sows were immunized by using different prime-boost protocols; one sow (C-L) was primed orally with TGEV capsules and boosted with the intramuscular administration of the live attenuated TGEV H5 strain. The other sow (Cx5) was prime-boosted with five consecutive oral administrations of TGEV capsules. 【Result】 The TGEV capsule remained solid in artificial gastric fluid (pH3), and gradually dissolved in artificial intestinal fluid (pH7) in vitro (Figure1). Both vaccination protocols elicited TGEV-specific IgG, IgA and neutralizing antibody responses in sera and colostrum/milk (Figure2). After farrowing neonates from the C-L and Cx5 sows were fed either with their mother's milk or with artificial milk. The neonates fed with mother's milk showed TGEV-specific antibodies in their sera, implying a passive transfer of maternal antibodies. All neonates were challenged with a virulent TGEV strain at 2 day after birth. The neonates fed with artificial milk exhibited severe TGE clinical symptoms at one day post infection (dpi) and most of them died by 4 dpi. In contrast, the onsets of TGE in the piglets fed with mother's milk were delayed, and they survived during the experimental period. The vaccine delivery system using enteric-coated capsule would be useful to protect against TGEV and other pathogens that infect their host via mucosal surfaces.

３．

Efficacy of APM777 vaccine in pigs challenged with Actinobacillus pleuropneumoniae serotype 2

Oshima, A.¹⁾, Ho T.¹⁾, Kamada, T.¹⁾, Teshima, K.¹⁾, Tsutsumi N.¹⁾
¹⁾ Nippon Institute for Biological Science
Asian Pig Veterinary Society Congress 2015, Manila
Abstract 【Introduction】 Respiratory　syndrome in swine, porcine respiratory disease complex (PRDC) has been described as an　important cause of decreased productivity in swine. Actinobacillus pleuropneumoniae (App) and Mycoplasma hyopneumoniae (Mhp) are the most important pathogens associated with PRDC. The objective of this study was to evaluate the efficacy and safety of APM777 vaccine, assess its ability to induce specific antibodies, and determine its ability to reduce App pneumonia. 【Materials and methods】 Safety and efficacy of APM777 vaccine in mice The vaccine contains 7 components　in alum adjuvant, inactivated bacterin of Mhp, three inactivated App cells (serovars 1, 2 and 5), three toxoids (recombinant ApxI, ApxII and ApxIII). The tests for Safety and efficacy were carried out according to the procedure described in the Japanese Standard of Veterinary biological Products. For safety test, each of 10 mice was injected intraperitoneally (i.p.) with 0.5 ml of the vaccine. Health status and body weight were monitored and recorded just before and 7 days after the injection. For App efficacy test, mice were immunized i.p. with 0.5 ml of the vaccine preparation diluted 1:20 with PBS. Two weeks after the immunization, the immunized and control mice (10 each) were challenged with App serovars 1, 2 and 5. Mouse mortality was monitored daily for the following 7 days. For Mhp efficacy test, each of 10 mice were immunized i.p. with 1 ml of the vaccine. Blood samples were collected at week 4 after the immunization for the determination of anti-Mhp antibodies by ELISA. Safety and efficacy of APM777 vaccine in pigs Trial. 1. SPF pigs (five per group) were vaccinated intramuscularly with 2 mL of APM 777 vaccine twice at 4-week intervals. The vaccinated pigs were daily observed for adverse reactions following injection of the vaccine. Eight weeks after the second immunization, the vaccinated and control pigs were challenged with about 10^3 cfu/head of App 2 via intratracheal route. Trial. 2. Pigs were vaccinated at 3- or 5-week intervals. Two weeks after the second injection, the vaccinated and control pigs were challenged as mentioned above. In both trials, after the challenge, clinical signs and death were monitored and recorded. Dead pigs were autopsied on the day of death, and pigs that survived were euthanized and autopsied 1 week after challenge. 【Result and Discussion】 Safety and efficacy testing in mice None of the mice treated with APM 777 showed any abnormal clinical signs. The average body weight returned to the starting level on day 4. After challenge with App serovars 1, 2 and 5; 9 to 10 (90 to 100%) of the control mice died within 4 days. In contrast, 9 to 10 (90 to 100%) of the immunized mice survived until day 7, when the experiment was terminated. The average anti-Mhp antibody titer in sera of mice immunized was 2,560±SD, whereas that in sera of the control mice was 20±SD. Safety and efficacy testing in pigs Abnormal clinical signs or local reactions were not observed in all pigs following the vaccination. After challenge with App serovar 2; 4 of 5 control pigs died, while 4 of 5 vaccinated pigs survived. All the animals developed pulmonary lesions, pigs immunized with APM 777 vaccine had significantly lower lesion scores of App pneumonia than the control pigs (5.8 vs 11.2). Antibody titers to the App serovars 1, 2 and 5 as well as ApxI, ApxIII and Mhp antigens in vaccinated group were higher than those of control group at 8 weeks after the second immunization. Interval between 1st and 2nd vaccination in pig After vaccination, no pigs got fever. Four of the five controls died, while all vaccinated pigs in 3 and 5 weeks intervals survived. All the animals developed pulmonary lesions, with a mean lesion score of 6.0, 3.8 and 9.0 in the 3, 5 weeks and control groups, respectively. The antibody response of 3 and 5 interval vaccinated group at 2 weeks after the second injection was higher than control group.