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Ectoparasites of bats in the Neotropics are diverse and play numerous ecological roles as vectors of microbial pathogens and endoparasites and as food sources for other cave fauna living both on their hosts and in bat roosts. The ectoparasites of bats in Jalisco State of western Mexico have not been as well described as those of other states with recent checklists that have focused primarily on the Yucatan Peninsula. We captured bats from 2011-2015 on the south coast and Sierra de Amula, Jalisco using mist nets, and we removed ectoparasites by hand. We identified 24 species of streblid bat flies and six ectoparasitic mites from bats caught in mist nets. There were an additional eight possibly undescribed species of Streblidae. Our collections extend the known range of species into Jalisco., (© 2016 The Society for Vector Ecology.)

California (CAL) serogroup Bunyaviruses are significant agents of arboviral encephalitis in humans. They are maintained and transmitted in nature by mosquitoes to preferred vertebrate amplifying hosts. The G2 envelope glycoprotein of La Crosse virus (LAC) was proposed by Ludwig et al. to be a determinant for virus attachment to mosquito midgut cells. Monoclonal antibodies to G2 neutralize the infectivity of pronase-treated virus for mosquito cells. We determined the location of antigenic sites on the LAC G2. We showed that antigenic areas present on the LAC G2 protein are conserved among viruses in the California encephalitis and Melao subgroups of the CAL serogroup, but not in trivatattus virus, nor within the BUN serogroup. A comparison of the G2 exodomain amino acid sequences of eight CAL and three BUN viruses with monoclonal antibodies (MAb) binding data predicted the possible location of the antigenic sites. We used in vitro mutagenesis of the LAC G2 gene to construct a set of G2 genes with replacement sequences in the coding regions for the suspected MAb binding sites. The native and mutated proteins were expressed in Hela cells and the ability of MAbs to bind to the expressed proteins was tested. Four discontinuous amino acid sequences, conserved among eight CAL serogroup viruses, were identified as contributing to two conformational binding domains for neutralizing LAC G2 MAbs.

Bacteria with inhibitory activity against Clostridium botulinum type C were isolated from 32% of sediment samples (n = 1600) collected from 10 marshes in a northern California wetland over a 12 mo period. Aerobic and anaerobic bacteria with inhibitory activity were isolated from 12% and 23% of the samples, respectively. Bacteria with inhibitory activity were isolated from all 10 study sites and throughout the year. This study demonstrates that bacteria with inhibitory activity against C. botulinum type C occur naturally in wetland sediments.

We examined the usefulness of mongolian gerbils (Meriones unguiculatus) as a new animal model for La Crosse virus (LACV) studies. Gerbils were exposed to LACV by either intramuscular (im) inoculation or exposure to transovarially infected Aedes triseriatus. Our studies indicate that gerbils may be a suitable animal model for LACV infection. Gerbils were susceptible to LACV, survived viral infection, and developed viremias and neutralizing antibody titers following exposure by im injection and by the bite of infected mosquitoes. Moreover, they are attractive to mosquito vectors. Gerbils have other advantages as laboratory vertebrate hosts for LACV; they are inexpensive, breed in captivity, and are usually mild-mannered and easy to handle. Thus, gerbils are a suitable model in the study of LACV pathogenesis as well as of transplacental and vector transmission.

The transplacental transmission of La Crosse virus (LACV) was evaluated in domestic rabbits (Oryctolagus cuniculus) and Mongolian gerbils (Meriones unguiculatis) as a potential mechanism for the maintenance of the virus. Rabbits were infected with LACV at different times of gestation by injection of viral suspensions or by exposure to LACV transovarially (TO) infected Aedes triseriatus. Pregnant gerbils were exposed between 16-24 days of gestation to LACV TO- infected Ae. triseriatus. Our results indicate that LACV can infect gerbils in utero. The LACV was isolated from the brain of suckling gerbils that died 3-5 days after birth from LACV-exposed mothers, representing the first evidence of LACV transplacental transmission. Microgliosis was found histologically in the cerebral cortex. In addition, LACV infection of both pregnant gerbils and rabbits resulted in in utero and neonatal mortality. La Crosse virus was not detected in surviving young of infected rabbits even after immunosuppression by administration of cyclophosphamide. Thus, there was no evidence of persistent infection of rabbits following in utero exposure. Surprisingly, some of the infected pregnant gerbils developed progressive paralysis 9-14-days postexposure, and LACV was isolated from the brains of these animals. Histopathologic studies of these tissue samples showed acute meningoencephalitis. The effects of natural LACV infection should be studied in pregnant amplifying hosts, such as chipmunks and squirrels, and in pregnant women.

Susceptibility of New World waterfowl to the Lake Andes strain of duck plague virus (DPV) was assessed by intramuscular inoculation of adult muscovies (Cairina moschata), mallards (Anas platyrhynchos), Canada geese (Branta canadensis), wood ducks (Aix sponsa), redheads (Aythya americana), gadwalls (Anas strepera), blue-winged teal (Anas discors), and pintails (Anas acuta). The relative virulence of DPV strains isolated from five United States and one Canadian location was established in muscovies, mallards, and Canada geese. Differences in DPV strain virulence were detected by formation of plaques in cell culture. Two strains that consistently formed plaques killed adult mallards while non-plaque forming strains killed hatchling but not adult mallards. Based on mortality after exposure to the Lake Andes strain, blue-winged teal, then wood ducks and redheads were highly susceptible, muscovies and gadwalls moderately susceptible, mallards and Canada geese less susceptible, and pintails the least susceptible. Mean death times were significantly (P < 0.01) different between adult muscovies (4.5 days) versus mallards and Canada geese (5.8 days each). Mean death time of the virulent Lake Andes and Minnesota strains were shorter (P < 0.05) than for the other four, less virulent DPV strains. Four of the less virulent strains killed hatchling but not adult mallards. Susceptibility to mortality was dependent upon age and route of inoculation. The intramuscular route of inoculation required the least amount of virus to kill mallard and muscovy ducks, the intranasal and conjunctival routes required more virus, and the oral route the most virus. This study was conducted from 1974 to 1977 between the months of September and April, with the exception of two titrations conducted in early May at the University of Wisconsin Department of Veterinary Science and the Charmany research facility of the University of Wisconsin-Madison.

To further understand the role of wild mammals in the maintenance of La Crosse virus (LACV) in nature, we investigated the effects of inoculation method and virus source on the duration and amplitude of LACV viremia in vertebrate hosts. Earlier work suggested that deer are not sufficiently susceptible to LACV to play an important role in its maintenance. We re-evaluated the susceptibility of deer since subsequent studies showed that they constitute 65% of Aedes triseriatus blood meals, and thus would be exposed frequently to the virus. In our study, deer developed higher and longer viremia following exposure to LACV by infected Ae. triseriatus than those previously reported by inoculation with needle and syringe. However, susceptible Ae. triseriatus that fed on these viremic animals did not become infected. Because a large number of uninfected mosquitoes can feed upon a viremic deer in nature, we believe that deer should not be disregarded completely as a possible amplifier in the LACV transmission cycle. We also infected chipmunks to determine if there were significant differences in viremia response from mosquito delivery of virus to the chipmunk host, compared with artificial exposure by injection. Chipmunks exposed to infected mosquitoes had higher and longer viremias than the ones produced by intramuscular injection of an LACV suspension. These findings show the importance of using LACV infected mosquitoes for transmission experiments in mammals.