The antigenic variability of the 15 kD nucleocapsid protein of porcine reproductive and respiratory syndrome (PRRS) virus was characterized with a panel of 24 monoclonal antibodies (MAbs) raised against the American PRRS virus isolate ISU-P. Five continuous epitopes designated EpORF7-A through E were revealed by the reactivity pattern of these MAbs with 67 American field isolates, two modified-live vaccine viruses, and the European Lelystad virus as determined by the indirect immnofluorescence assay and Western immunoblotting and confirmed by additivity and blocking enzyme-linked immunosorbent assays. The reactivity pattern of isolates in the IFA permitted their subdivision into 4 American antigenic groups which represented 84.1, 11.6, 2.9 and 1.4% of viruses tested. The antigenic variation among isolates was correlated to single, group specific nucleotide substitutions and mediated by a combination of at least 4 of the 5 epitopes. EpORF7-A was conserved in all American isolates and the Lelystad virus which constituted a separate antigenic group. Consequently, monoclonal antibodies specific for EpORF7-A may prove useful as the antigenic basis for a universal diagnostic test for the PRRS virus. EpORF7-C, D and E were only present in the American isolates tested.

The longevity of an Iowa strain of Culex tarsalis Coquillett fed blood meals containing 2 concentrations of western equine encephalomyelitis virus from Iowa (WEE-7738) was compared with that of Cx. tarsalis fed blood without virus. Females exposed to 4.7-5.0 log TCID50 per mosquito of WEE-7738 did not live as long as mosquitoes exposed to 2.7-3.0 log TCID50 per mosquito or controls. Only 1% of mosquitoes fed blood containing the higher virus concentration survived to day 18 after exposure. However, 13% of mosquitoes fed blood with the lower virus titer and 19.5% of the controls were still alive on day 18 after exposure. Flight activity scores of Cx. tarsalis infected with 4.7-5.0 log TCID50 per mosquito of WEE-7738 were 27.5% lower, and there were 26.1% fewer spontaneous flights than noninfected controls from days 6-11 after infection. After day 8 after infection, infected Cx. tarsalis had 37.1% lower activity scores and 40.0% fewer spontaneous flights than noninfected controls. Virus infection did not affect how long a mosquito flew in a 24-h period (the daily flying time) or the duration of individual flights. The spontaneous flight activity pattern (circadian rhythm) of infected mosquitoes was identical to those of controls. Both infected and noninfected mosquitoes began spontaneous flight activity at 2000-2100 hours (CST) and were active throughout the entire dark phase of the 24-h cycle. Although mosquitoes were active throughout the night, there was a burst or peak of activity between 2200 and 2300 hours when the complete dark cycle began. These results indicate that the adverse effect of WEE infection on longevity and spontaneous flight activity of Cx. tarsalis may decrease vectorial capacity of Cx. tarsalis for WEE.

Five cases of human babesiosis were reported in the Lower Hudson Valley Region of New York State in 2001. An investigation to determine if Babesia microti was present in local Ixodes scapularis ticks yielded 5 positive pools in 123 pools tested, the first detection of B. microti from field-collected I. scapularis in upstate New York.

The longevity and fecundity of overwintered Unaspis yanonensis Kuwana (Homoptera: Diaspididae) were examined at constant temperature 24°C, and its periodical oviposition activity was modeled. Adult females collected in early November showed abnormal post-diapause development; prolonged pre-oviposition period, not producing progenies and much lower fecundity. All females collected from early December through early March showed normal post-diapause development and had Ϸ20 d of pre-oviposition period and Ϸ80 d of longevity. Overwintered U. yanonensis showed a periodical oviposition activity with a maximum 4 times of oviposition cycle during their life time, and the pattern was flexibly fitted to a 4-peak Gaussian function. The average peak timings (parameter a) occurred at 5.5, 25.2, 41.6, and 56.4 d for the 1st, 2nd, 3rd, and 4th peak from the start of oviposition, respectively. The height of the peaks (parameter b) gradually decreased from 14.9 for the 1st peak to 5.0 for the 4th peak. The parameter values of the 4-peak equation were successfully converted to degree-days unit with a lower threshold temperature 13°C for field validation. The model predicted the 1st oviposition peak of overwintered U. yanonensis very well (Ϸ282 DD from 1 January), while showed large discrepancy with actual data in the later peak period. A 3-modal oviposition curve that includes the individual variations of oviposition activity of U. yanonensis females with removing the 4th cycle showed a better shape fitting ability in the later peak period. Further, application and improvement of the multi-peak model were discussed.

A particular empirical equation for rainfall kinetic energy is needed to compute rainfall erosivity, calculated by the annual sum of the product of total rainfall energy and maximum 30-min rainfall intensity. If rainfall kinetic energy equation was different, rainfall erosivity will be produced differently. However, the previous studies in Korea had little concern about rainfall kinetic energy equation and it was not clear which rainfall kinetic energy is suitable for Korea. The purpose of this study is to analyze and evaluate the difference of the rainfall erosivity based on different rainfall kinetic energy equations obtained from previous studies. This study introduced new rainfall erosivity factors based on rainfall kinetic energy equation of Noe and Kwon (1984) that is only regression model developed in Korea. Data of annual rainfall erosivity for 21 weather stations in 1980~1999 were used in this study. The result showed that rainfall erosivity factors by the previous equations had been about 10~20% overestimated than rainfall erosivity by Noe and Kwon (1984)'s equation in Korea.