We investigated the response to challenge infection with Cryptosporidium parvum oocysts in immunosuppressed C57BL/6N mice. In the primary infection, fecal oocyst shedding and parasite colonization were greater in immunosuppressed mice than in nonimmunosuppressed mice. Compared with primary infection, challenge infection with C. parvum didn't show any oocyst shedding and parasite colonization. Especially, oocyst shedding and parasite colonization from the mice infected with heatkilled oocysts were not detected. After challenge infection with C. parvum oocysts, however, these mice were shedding small numbers of oocysts and parasite colonization. Except normal control and uninfected groups, the antibody titers of other groups appear similar. Based on the fecal oocyst shedding, parasite colonization of ilea, and antibody titers in the mice, these results suggest that the resistance to challenge infection with C. parvum in immunosuppressed C57BL/6N mice has increased.
Animals ; Antibodies, Protozoan/blood ; Cryptosporidiosis/*immunology/*parasitology ; Cryptosporidium parvum/*immunology ; Dexamethasone/immunology ; Enzyme-Linked Immunosorbent Assay ; Feces/parasitology ; Female ; Fluorescent Antibody Technique, Indirect ; Histocytochemistry ; Ileum/parasitology ; Immunocompromised Host ; Mice ; Mice, Inbred C57BL ; Oocysts/immunology ; Random Allocation

The present study surveyed the prevalence of natural infection of the sheep esphagus muscle with sarcocysts of Sarcocystis ovicanis and examined induction of protective immunity using UV-attenuated sporocysts. The overall prevalence of natural infection of the sheep was 95%. Infectivity of the collected sarcocysts was confirmed by shedding of sporulated oocysts after feeding infected esophageal tissues to dogs. To induce protective immunity, lambs were immunized 3 times (once a week) with 1.5 x 10(4) sporocysts exposed to UV-light for 30 min (UV-30 group) or 60 (UV-60 group) min and then challenged with 1.5 x 10(4) normal sporocysts at the 3rd week post the 1st vaccination. These lambs showed high survival and less clinical signs of sarcocystosis than normal infected lambs. The attenuated sporocysts produced abnormal cysts; small in size and detached from the muscle fiber. These abnormalities were more obvious in UV-60 group than UV-30 group. Also, the IFN-gamma level and lymphocyte percentage were increased while the total leukocyte count was decreased in the UV-60 group compared with other groups. The high level of IFN-gamma may be an evidence for the induction of Th1 responses which may have protective effect against a challenge infection.
Animals ; Dogs ; Esophagus/parasitology ; Feces/parasitology ; Interferon-gamma/secretion ; Lymphocytes/immunology ; Oocysts/*immunology ; Peptide Fragments/secretion ; Prevalence ; Protozoan Vaccines/immunology ; Sarcocystis/cytology/*immunology/*radiation effects ; Sarcocystosis/epidemiology/immunology/prevention & control/*veterinary ; Severity of Illness Index ; Sheep/immunology/parasitology ; Sheep Diseases/immunology/*prevention & control ; Survival Analysis ; *Ultraviolet Rays ; Vaccines, Attenuated/immunology

Cryptosporidium parvum oocysts were isolated from a child suffering from acute gastroenteritis and successfully passaged in a calf and mice (designated hereafter SNU-H1) in the Republic of Korea; its molecular genotype has been analyzed. The GAG microsatellite region was amplified by a polymerase chain reaction (PCR), with a 238 base pair product, which is commonly displayed in C. parvum. The isolate was shown to be a mixture of the genotypes 1 (anthroponotic) and 2 (zoonotic). To study its infectivity in animals, 2 calves and 3 strains of mice were infected with the SNU-H1; in these animals, the propagation of both genotypes was successful. In immunosuppressed (ImSP) BALB/c and C57BL/6 mice the number of oocysts decreased after day 10 post-infection (PI) ; but in ImSP ICR mice, they remained constant until day 27 PI. The results show that both the C. parvum genotypes 1 and 2 can be propagated in calves and ImSP mice.
Animals ; Cattle ; Child ; Cryptosporidiosis/microbiology ; Cryptosporidium parvum/*genetics/immunology ; Diarrhea/parasitology ; Feces/parasitology ; Genotype ; Human ; Korea ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Inbred ICR ; Oocysts ; Polymerase Chain Reaction ; Support, Non-U.S. Gov't ; Zoonoses/parasitology

We observed the time gap between oocyst shedding and antibody responses in mice (3-week-old C57BL/6J females) infected with Cryptosporidium parvum. Oocyst shedding was verified by modified acid-fast staining. The individually collected mouse sera were assessed for C. parvum IgM and IgG antibodies by enzyme-linked immunosorbent assay from 5 to 25 weeks after infection. The results showed that C. parvum oocysts were shed from day 5 to 51 post-infection (PI). The IgM antibody titers to C. parvum peaked at week 5 PI, whereas the IgG antibody titers achieved maximum levels at week 25 PI. The results revealed that IgM responses to C. parvum infection occurred during the early stage of infection and overlapped with the oocyst shedding period, whereas IgG responses occurred during the late stage and was not correlated with oocyst shedding. Hence, IgM antibody detection may prove helpful for the diagnosis of acute cryptosporidiosis, and IgG antibody detection may prove effective for the detection of past infection and endemicity.
Animals ; Antibodies, Protozoan/*biosynthesis/blood ; Cryptosporidiosis/*immunology ; Cryptosporidium parvum/*immunology/isolation & purification ; Enzyme-Linked Immunosorbent Assay ; Feces/parasitology ; Female ; Immunocompromised Host ; Immunoglobulin G/biosynthesis/blood ; Immunoglobulin M/biosynthesis/blood ; Mice ; Mice, Inbred C57BL ; Oocysts/immunology ; Specific Pathogen-Free Organisms ; Time Factors

Neospora caninum is an important cause of abortion in dairy cattle worldwide. Dog is the definitive host for N. caninum and can infect dairy cattle. The aim of this study is to determine the prevalence of Neospora oocysts in feces of dogs from dairy farms. A total of 174 fecal samples was collected from 89 farm dogs and 85 household dogs during 2006 and 2008. Fecal samples of dogs were microscopically examined for detecting Hammondia Neospora-like oocysts (HNLO) by Mini Parasep(R)SF fecal parasite concentrator. HNLO were microscopically detected in 4 fecal samples (2.2%). The fecal samples with HNLO were examined by N. caninum-specific PCR. Two of the samples were positive for N. caninum. The 2 positive fecal samples were selected for inoculation to calves. Two inoculated calves were seronegative by ELISA for 4 months post-infection. This is the first report of finding N. caninum DNA in feces of farm dogs in Mashhad area, Iran.
Animals ; Antibodies, Fungal/blood ; Cattle ; Cattle Diseases/immunology/parasitology ; Coccidiosis/epidemiology/parasitology/*veterinary ; DNA, Fungal/genetics/isolation & purification ; Dog Diseases/*epidemiology/*parasitology ; Dogs ; Enzyme-Linked Immunosorbent Assay/methods ; Feces/*microbiology ; Iran/epidemiology ; Male ; Microscopy/methods ; Neospora/*genetics/*isolation & purification ; Oocysts/cytology ; Polymerase Chain Reaction/methods ; Prevalence