A Comparative Study on the use of Virus and Antibody Detection Techniques for the Diagnosis of La Piedad Michoacan Paramyxovirus (LPMV) Infection in Pigs

Abstract

Abstract. La Piedad Michoacan paramyxovirus (LPMV) is newly recognized paramyxovirus that has been associated with neurologic and reproductive disorders in pigs in Mexico. To date, no comparative study of methods for the diagnosis of infection with this virus has been published. In this study, we identified tissues containing maximum virus load to optimize virus isolation procedures, and we compared this method to a rapid diagnostic test employing immunostaining of impression smears for LPMV antigens. In addition, several of the available tests for detecting LPMV antibodies were compared for their sensitivity in detecting seroconversion. Pigs used for the study of virus load in tissues and serologic studies were inoculated at 17 days of age with 10 7.00 TCID 50 of LPMV. Serial blood samples were collected from selected pigs, and selected pigs were necropsied over a 14-day period. Pigs used in the investigation comparing standard virus isolation techniques to immunostaining of impression smears were inoculated at 3 days of age as described above and necropsied over an 8-day period. The results demonstrate that in the 17-day-old pigs maximum virus titers were detected in olfactory bulb at 5 days postinoculation (PI) and in midbrain at 9 days PI. In addition, the most consistent recovery of high titer virus was from tonsil (3-9 days PI) and olfactory bulb (4-9 days PI). Immunostaining of impression smears was as sensitive as virus isolation when selected tissues (lung, midbrain, olfactory bulb) were compared, with virus detected by both methods in 11/13 samples and in 1 sample each by immunostaining and virus isolation, respectively. All of the serology tests investigated detected seroconversion in pigs by 8 days PI. The identification of target organs where highest virus titers are found combined with immunofluorescent methods for the detection of LPMV antigens and a comparative study of the available serologic tests should facilitate the selection of techniques suitable for any laboratory to diagnose LPMV infection in pigs.

Development of a Blocking ELISA for Screening Antibodies to Porcine Rubulavirus, La Piedad Michoacan Virus

“…8 The results showed that all 4 tests gave satisfactory results. However, these tests have the following disadvantages.…”

“…The results presented in Table 2 concerning the experimentally infected boars in Mexico show that all 3 boars were positive on the b-ELISA on day 9, i.e., in agreement with the results of the previous experiment. 8 Field sera from Mexico. All 597 field sera from Mexico were tested by b-ELISA: 431 were positive, and 166 were negative.…”

“…Blood samples from 3 piglets experimentally infected with LPMV were collected on days 0, 5, 8, 11, and 14, and selected sera from the animals were tested by indirect ELISA and HI, IIF, and VN tests. 8 In the present study, the b-ELISA was used to retest the sera from the 3 piglets. The results were in agreement with those of the previous study 8 (see Table 1).…”

“…8 In the present study, the b-ELISA was used to retest the sera from the 3 piglets. The results were in agreement with those of the previous study 8 (see Table 1). The results presented in Table 2 concerning the experimentally infected boars in Mexico show that all 3 boars were positive on the b-ELISA on day 9, i.e., in agreement with the results of the previous experiment.…”

“…In an experiment carried out in Belfast, 8 3 pigs (3 days old) were inoculated with 10 7 TCID 50 of LPMV-85 strain. This inoculum was administrated in a 10-ml volume given as 2 4.5-ml doses by the intranasal route and 2 0.5-ml doses by the intraconjunctival route, 6 hr apart.…”