• Parasites, Hosts and Diseases
• /
• 제40권4호
• /
• pp.181-186
• /
• 2002

To examine the fate of Strongyloides venezuelensis, Mongolian gerbils (Meriones unguicalatus) were orally infected with 1,000 $L_{3}$ larvae per animal. Altogether, 50 gerbils divided into 5 groups of 10 each were monitored for a period of 570 days to document the kinetics of faecal egg output, adults worm population, morphological development, fecundity, and hematological changes including peripheral blood eosinophilia. This study chronicled a life long parasitism of S. venezuelensis in the gerbil host, and showed that S. venezuelensis infection was quite stable throughout the course of infection and the worms maintained their normal development as evidenced by their body dimension. A progressive loss of body condition of the infected gerbils was observed as the level of infection advanced. However, no detectable pathological changes were observed in the gastrointestinal tract. The present findings indicate that an immunocompetent host, such as the Mongolian gerbil, can serve as a life long carrier model of S. venezuelensis if the worms are not expelled within 570 days after infection.

• Parasites, Hosts and Diseases
• /
• 제37권2호
• /
• pp.101-107
• /
• 1999

Rats were immunized through an initial infection with 1,000 filariform larvae (L3) of Nippostrongylus brasiliensis and after complete expulsion of worms they were challenged with 1,000 L3 of Strongyloides venezuelensis to investigate whether cross-resistance developed against a heterologous parasite. Nippostrongylus brasiliensis immunized rats developed a partial cross-resistance against S.venezuelensis migrating larvae (MSL3) in the lungs and adult worms in the small intestine. The population of MSL3 in the lungs were significantly lower (p<0.05) in immunized rats($22.0{\;}{\pm}{\;}7.4$) compared with controls ($105.0{\;}{\pm}{\;}27.6$). The populations of adult worms, egg output and fecundity were initially decreased but from day 14 post-challenge they did not show any significant difference between immunized and control rats. However, the length of worm in immunized rat was revealed as retardation. Peripheral blood eosinophilia was significantly decreased (P<0.05) on day 7 post-challenge and then gradually increased which peaked on da 42 post-challenge when most of the worms were expelled. these results suggest that peripheral blood eosinophilia is strongly involved in the worm establishment and expulsion mechanisms.

• Parasites, Hosts and Diseases
• /
• 제37권1호
• /
• pp.13-19
• /
• 1999

The effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae ($L_3$) to rats were investigated. A significantly higher body length was observed in $L_3$ from filter paper culture ($597.3{\;}{\pm}{\;}32.2{\;}{\mu\textrm{m}}$) than those in fecal (($509.9{\;}{\pm}{\;}35.0{\;}{\mu\textrm{m}}$) and nutrient broth culture (503.3{\;}{\pm}{\;}31.0{\;}{\mu\textrm{m}}) (P<0.05). Larval infectivity was assessed by exposing rats to 1,000 $L_3$ from each culture and worms were recovered from the lungs and small intestines. Recovery rate of these worms did not show any significant difference. A significantly greater body length of adults was recorded in those corresponding to the $L_3$ harvested from filter paper (2,777.5{\;}{\pm}{\;}204.4{\;}{\mu\textrm{m}}$) and nutrient broth culture (($2.732.5{\;}{\pm}{\;}169.8{\;}{\mu\textrm{m}}$) than those corresponding to the $L_3$ obtained from fecal culture (($2.600.5{\;}{\pm}{\;}172.4{\;}{\mu\textrm{m}}$) (P<0.05). Although worm fecundity and EPG counts differed among culture methods but worm burdens and course of infection did not. These findings suggest that the methods of cultures have a significant effect on the morphological development of the larvae to the $L_3$ stage, but do not influence the infectivity to rats.

• Parasites, Hosts and Diseases
• /
• 제36권1호
• /
• pp.15-22
• /
• 1998

Strongyloides venezuelensis을 자유생활형 유충을 얻고자, 쥐의 분변 물질을 첨가한 영양 배지를 polyvinyl bag에 넣어 배양하는 배양기술을 확립하였다 포화식염수법으로 회수한 충란의 부화율은 배양 온도에 따라서 다르게 관찰되었는데 (Y = $-0.192X^2$ + 8.673x - 19.550, r = 0.901) $^25{\circ}C$에서 100% 부화율을 나타내었지만 온도가 낮거나 높아도 감소되는 양상을 나타내었다. 회수 한 충란 $^20{\circ}C$에서 5일간 관찰하였을 때 자유생활형 유충으로의 발육률은 영양 배지의 농도를 증가시키면 증가하여 0 12%에서 최고치를 보이다가 다시 낮아지는 양상을 보여 (Y = $-864.032X^2$ + 245.995X - 0.560, r = 0.875), 감염형 3기 유충($L_3$)으로의 발육률은 배양 온도에 따라서 다르게 관찰되었다 즉, $^25{\circ}C$에서 가장 높아서 20%에 달하며 $15^{\circ}C$는 10.9%, 그리고 $^20{\circ}C$에서는 18.1%로 나타났다 (Y = $-0.189X^2$ + 8.387x - 72 795 r = 0.981). 그렇지만 감염 유충으로 성장하는데 필요한 기간도 역시 온도의 변화와 관련이 있어 온도가 높으 면 높을수록 소요되는 시간이 잔게 나타났다 (Y = $0.035X^2$ - 2.025X + 32.375, r = 0.995) 이상의 결과로 미루어 보아 감염 유충의 최대 회수율 (19.2%)은 15,000개를 polyvinyl bag에 0.12% 영양 배지와 더불어 $^25{\circ}C$에서 5일간 배양하였을 때 얻을 수 있었다. 이처럼 새로이 고안한 Skonavloides 속의 기생충 배양 기술은 화학 물질, 구충제, 제초제에 대한 선별검사와 기생충과 관련된 면역학적 연구에 생물학적 도구로서 사용될 수 있을 것으로 기대된다. 저자는 S. venezuelensis의 국문 이름을 베네수엘라분선충으로 제안한다.

• 대한의생명과학회지
• /
• 제8권4호
• /
• pp.223-228
• /
• 2002

In vitro bioassays of aqueous extracts of 25 herbal species were performed by ovicidal activity against Strongvloides venuelensis. 500 mg of feces from Mongorian gerbil infected with S. venuelensis were placed into polyvinyl culture with extracts of herb and anthelmintic drugs in triplicates. Larval activity inside the polyvinyl bag was recorded microscopically at 12 hours, and every 24 hours thereafter for up to 72 hrs incubation. Eggs were not hatched within 72 hrs and degeneration was evident in the presence of extracts. The ovicidal activity characterized by the absence of L$_3$ in fecal cultures inside the polyvinyl bag. 1. Among 25 herbs, 12 herbs had ovicidal effects and caused degeneration of larvae in egg. S. angustifolia, I. helenium, A. korenum, P. tenuifolia, F. virridissima, A. asiatica, S. chinensis, A. tataricus, S. baicalensis, M. rimosa, S. glabra and Z. piperitum were the most ovicidal effect. However, P. thunbergiana, T. chinensis, C. flos, G. uralensis, C. obutusifolia, C. fortunei, A. koreana, P. grandiflorum, P. tenuifolia (Radix), P. mume and A. asphodelodes showed no ovicidal effects in vinyl bag culture. 2. Of 25 hrebs, 4 herbs had ovicidal and wormicidal effects, P. thunbergiana, C. flos, B. Striata and T. chinensis were characterized by degeneration of larvae.

• Parasites, Hosts and Diseases
• /
• 제36권2호
• /
• pp.99-108
• /
• 1998

베네수엘라분선충의 충란, 자충 띤 성충을 장기간 보존할 수 있는 방안을 마련하기 위하여 여러 가지 배양환경에 대한 연구를 수헝하였던 바, 다음과 같은 결과를 얻었다. 분변 내의 충란은 $4^{\circ}C$ 에서 25일간, 실온에서는 15일간 생존하였으며, 분변에서 분리한 충란은 $4^{\circ}C$의 생리적 식염수에 서 24시간 생존하였으나, 상실배기의 충란은 건조한 공기에 민감하여 12시간 내에 환성을 잃었다. 감염형 자충을 polyvinylbag에 넣어 $20^{\circ}C$에 보관하였을 경우, 분변 물질이 첨가된 0.12% 영양배 지에서는 45일, 영양배지는 28일간 생존하였다 한편, 영양배지에서 배양된 감염 자충은 상수에서 는 32일간, 멸균 식염수에서는 22일간 생존하였다. 인공감염시켜 얻은 성충은 $37^{\circ}C$에서 9일간, 9:1배지 (10% 쥐 혈청을 첨가)와 혈청을 첨가하지 않은 영양배지를 매일 교환하여 주어도 4일동안 밖에 생존하지 못하였다. 성충 암컷은 실험관 내에서 산란하고, 자충으로 부화되었지만 혈청을 첨가한 배지에서도 감염자충으로 발육하지 못하였다.

• Parasites, Hosts and Diseases
• /
• 제38권4호
• /
• pp.209-236
• /
• 2000

The last two decades witnessed significant advances in the efforts of immune-parasitologists to elucidate the nature and role of the host mucosal defence mechanisms against intestinal nematode parasites. Aided by recent advances in basic immunology and biotechnology with the concomitant development of well defined laboratory models of infection, immunoparasitologists have more precisely analyzed and defined the different immune effector mechanisms during the infection; resulting in great improvement in our current knowledge and understanding of protective immunity against gastrointestinal (GI) nematode parasites. Much of this current understanding comes from experimental studies in laboratory rodents, which have been used as models of livestock and human GI nematode infections. These rodent studies, which have concentrated on Heligmosomoides polygyrus, Nippostrongylus brasiliensis, Strongyloides ratti/5. venezuelensis. Trichinella spiralis and trichuris muris infections in mice and rats, have helped in defining the types of T cell responses that regulate effector mechanisms and the effector mechanisms responsible for worm expulsion. In addition, these studies bear indications that traditionally accepted mechanisms of resistance such as eosinophilia and IgE responses may not play as important roles in protection as were previously conceived. In this review, we shall, from these rodent studies, attempt an overview of the mucosal and other effector responses against intestinal nematode parasites beginning with the indices of immune protection as a model of the protective immune responses that may occur in animals and man.